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Hsu D, Flynn JR, Schuler CJ, Santelli CM, Toner BM, Bond DR, Gralnick JA. Isolation and genomic analysis of " Metallumcola ferriviriculae" MK1, a Gram-positive, Fe(III)-reducing bacterium from the Soudan Underground Mine, an iron-rich Martian analog site. Appl Environ Microbiol 2024; 90:e0004424. [PMID: 39007603 PMCID: PMC11337815 DOI: 10.1128/aem.00044-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Accepted: 06/18/2024] [Indexed: 07/16/2024] Open
Abstract
The Soudan Underground Mine State Park, found in the Vermilion Iron Range in northern Minnesota, provides access to a ~ 2.7 billion-year-old banded iron formation. Exploratory boreholes drilled between 1958 and 1962 on the 27th level (713 m underground) of the mine intersect calcium and iron-rich brines that have recently been subject to metagenomic analysis and microbial enrichments. Using concentrated brine samples pumped from a borehole depth of up to 55 m, a novel Gram-positive bacterium was enriched under anaerobic, acetate-oxidizing, and Fe(III) citrate-reducing conditions. The isolated bacterium, designated strain MK1, is non-motile, rod-shaped, spore-forming, anaerobic, and mesophilic, with a growth range between 24°C and 30°C. The complete circular MK1 genome was found to be 3,720,236 bp and encodes 25 putative multiheme cytochromes, including homologs to inner membrane cytochromes in the Gram-negative bacterium Geobacter sulfurreducens and cytoplasmic membrane and periplasmic cytochromes in the Gram-positive bacterium Thermincola potens. However, MK1 does not encode homologs of the peptidoglycan (CwcA) and cell surface-associated (OcwA) multiheme cytochromes proposed to be required by T. potens to perform extracellular electron transfer. The 16S rRNA gene sequence of MK1 indicates that its closest related isolate is Desulfitibacter alkalitolerans strain sk.kt5 (91% sequence identity), which places MK1 in a novel genus within the Desulfitibacteraceae family and Moorellales order. Within the Moorellales order, only Calderihabitans maritimus strain KKC1 has been reported to reduce Fe(III), and only D. alkalitolerans can also grow in temperatures below 40°C. Thus, MK1 represents a novel species within a novel genus, for which we propose the name "Metallumcola ferriviriculae" strain MK1, and provides a unique opportunity to study a cytochrome-rich, mesophilic, Gram-positive, spore-forming Fe(III)-reducing bacterium.IMPORTANCEThe Soudan Underground Mine State Park gives access to understudied regions of the deep terrestrial subsurface that potentially predate the Great Oxidation Event. Studying organisms that have been relatively unperturbed by surface conditions for as long as 2.7 billion years may give us a window into ancient life before oxygen dominated the planet. Additionally, studying microbes from anoxic and iron-rich environments can help us better understand the requirements of life in analogous environments, such as on Mars. The isolation and characterization of "Metallumcola ferriviriculae" strain MK1 give us insights into a novel genus and species that is distinct both from its closest related isolates and from iron reducers characterized to date. "M. ferriviriculae" strain MK1 may also act as a model organism to study how the processes of sporulation and germination are affected by insoluble extracellular acceptors, as well as the impact of spores in the deep terrestrial biosphere.
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Affiliation(s)
- David Hsu
- BioTechnology Institute, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
- Department of Plant and Microbial Biology, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
| | - Jack R. Flynn
- BioTechnology Institute, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
- Department of Plant and Microbial Biology, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
| | - Christopher J. Schuler
- BioTechnology Institute, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
- Department of Earth and Environmental Sciences, University of Minnesota-Twin Cities, Minneapolis, Minnesota, USA
| | - Cara M. Santelli
- BioTechnology Institute, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
- Department of Earth and Environmental Sciences, University of Minnesota-Twin Cities, Minneapolis, Minnesota, USA
| | - Brandy M. Toner
- BioTechnology Institute, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
- Department of Earth and Environmental Sciences, University of Minnesota-Twin Cities, Minneapolis, Minnesota, USA
- Department of Soil, Water, and Climate, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
| | - Daniel R. Bond
- BioTechnology Institute, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
- Department of Plant and Microbial Biology, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
| | - Jeffrey A. Gralnick
- BioTechnology Institute, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
- Department of Plant and Microbial Biology, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
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2
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Lu J, Qing C, Huang X, Zeng J, Zheng Y, Xia P. Seasonal dynamics and driving mechanisms of microbial biogenic elements cycling function, assembly process, and co-occurrence network in plateau lake sediments. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 951:175510. [PMID: 39147055 DOI: 10.1016/j.scitotenv.2024.175510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2024] [Revised: 08/11/2024] [Accepted: 08/12/2024] [Indexed: 08/17/2024]
Abstract
Microbial community diversity significantly varies with seasonality. However, little is known about seasonal variation of microbial community functions in lake sediments and their associated environmental influences. In this study, metagenomic sequencing of sediments collected from winter, summer, and autumn from Caohai Lake, Guizhou Plateau, were used to evaluate the composition and function of sediment microbial communities, the potential interactions of functional genes, key genes associated with seasons, and community assembly mechanisms. The average concentrations of nitrogen (TN) and phosphorus (TP) in lake sediments were higher, which were 6.136 and 0.501 g/kg, respectively. TN and organic matter (OM) were the primary factors associated with sediment community composition and functional profiles. The diversity and structure of the microbial communities varied with seasons, and Proteobacteria relative abundances were significantly lower in summer than in other seasons (58.43-44.12 %). Seasons were also associated with the relative abundances of functional genes, and in particular korA, metF, narC, nrfA, pstC/S, and soxB genes. Network complexity was highest in the summer and key genes in the network also varied across seasons. Neutral community model analysis revealed that the assembly mechanisms related to carbon (C), nitrogen (N), phosphorus (P), and sulfur (S) cycle-related genes were primarily associated with random processes. In summary, diverse functional genes were identified in lake sediments and exhibited evidence for synergistic interactions (Positive proportion: 74.91-99.82 %), while seasonal factors influenced their distribution. The results of this study provide new insights into seasonal impacts on microbial-driven biogeochemical cycling in shallow lakes.
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Affiliation(s)
- Jiaowei Lu
- Key Laboratory for Information System of Mountainous Areas and Protection of Ecological Environment of Guizhou Province, Guizhou Normal University, Guiyang 550001, China
| | - Chun Qing
- Key Laboratory for Information System of Mountainous Areas and Protection of Ecological Environment of Guizhou Province, Guizhou Normal University, Guiyang 550001, China
| | - Xianfei Huang
- Key Laboratory for Information System of Mountainous Areas and Protection of Ecological Environment of Guizhou Province, Guizhou Normal University, Guiyang 550001, China
| | - Jin Zeng
- Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China
| | - Yikun Zheng
- Key Laboratory for Information System of Mountainous Areas and Protection of Ecological Environment of Guizhou Province, Guizhou Normal University, Guiyang 550001, China
| | - Pinhua Xia
- Key Laboratory for Information System of Mountainous Areas and Protection of Ecological Environment of Guizhou Province, Guizhou Normal University, Guiyang 550001, China.
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3
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Morriss CE, Cheung CK, Nunn E, Parmeggiani F, Powell NA, Kimber RL, Haigh SJ, Lloyd JR. Biosynthesis Parameters Control the Physicochemical and Catalytic Properties of Microbially Supported Pd Nanoparticles. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2311016. [PMID: 38461530 DOI: 10.1002/smll.202311016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 02/12/2024] [Indexed: 03/12/2024]
Abstract
The biosynthesis of Pd nanoparticles supported on microorganisms (bio-Pd) is achieved via the enzymatic reduction of Pd(II) to Pd(0) under ambient conditions using inexpensive buffers and electron donors, like organic acids or hydrogen. Sustainable bio-Pd catalysts are effective for C-C coupling and hydrogenation reactions, but their industrial application is limited by challenges in controlling nanoparticle properties. Here, using the metal-reducing bacterium Geobacter sulfurreducens, it is demonstrated that synthesizing bio-Pd under different Pd loadings and utilizing different electron donors (acetate, formate, hydrogen, no e- donor) influences key properties such as nanoparticle size, Pd(II):Pd(0) ratio, and cellular location. Controlling nanoparticle size and location controls the activity of bio-Pd for the reduction of 4-nitrophenol, whereas high Pd loading on cells synthesizes bio-Pd with high activity, comparable to commercial Pd/C, for Suzuki-Miyaura coupling reactions. Additionally, the study demonstrates the novel synthesis of microbially-supported ≈2 nm PdO nanoparticles due to the hydrolysis of biosorbed Pd(II) in bicarbonate buffer. Bio-PdO nanoparticles show superior activity in 4-nitrophenol reduction compared to commercial Pd/C catalysts. Overall, controlling biosynthesis parameters, such as electron donor, metal loading, and solution chemistry, enables tailoring of bio-Pd physicochemical and catalytic properties.
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Affiliation(s)
- Christopher Egan Morriss
- Department of Earth and Environmental Sciences, University of Manchester, Oxford Road, Manchester, M13 9PL, UK
- Department of Materials, University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Casey K Cheung
- Department of Materials, University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Elliot Nunn
- Department of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Fabio Parmeggiani
- Dipartimento di Chimica, Materiali ed Ingegneria Chimica "Giulio Natta", Politecnico di Milano, Piazza Leonardo da Vinci, Milan, 20133, Italy
| | | | - Richard L Kimber
- Department of Earth and Environmental Sciences, University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Sarah J Haigh
- Department of Materials, University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Jonathan R Lloyd
- Department of Earth and Environmental Sciences, University of Manchester, Oxford Road, Manchester, M13 9PL, UK
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Stewart DI, Vasconcelos EJR, Burke IT, Baker A. Metagenomes from microbial populations beneath a chromium waste tip give insight into the mechanism of Cr (VI) reduction. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 931:172507. [PMID: 38657818 DOI: 10.1016/j.scitotenv.2024.172507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2023] [Revised: 04/04/2024] [Accepted: 04/13/2024] [Indexed: 04/26/2024]
Abstract
Dumped Chromium Ore Processing Residue (COPR) at legacy sites poses a threat to health through leaching of toxic Cr(VI) into groundwater. Previous work implicates microbial activity in reducing Cr(VI) to less mobile and toxic Cr(III), but the mechanism has not been explored. To address this question a combined metagenomic and geochemical study was undertaken. Soil samples from below the COPR waste were used to establish anaerobic microcosms which were challenged with Cr(VI), with or without acetate as an electron donor, and incubated for 70 days. Cr was rapidly reduced in both systems, which also reduced nitrate, nitrite then sulfate, but this sequence was accelerated in the acetate amended microcosms. 16S rRNA gene sequencing revealed that the original soil sample was diverse but both microcosm systems became less diverse by the end of the experiment. A high proportion of 16S rRNA gene reads and metagenome-assembled genomes (MAGs) with high completeness could not be taxonomically classified, highlighting the distinctiveness of these alkaline Cr impacted systems. Examination of the coding capacity revealed widespread capability for metal tolerance and Fe uptake and storage, and both populations possessed metabolic capability to degrade a wide range of organic molecules. The relative abundance of genes for fatty acid degradation was 4× higher in the unamended compared to the acetate amended system, whereas the capacity for dissimilatory sulfate metabolism was 3× higher in the acetate amended system. We demonstrate that naturally occurring in situ bacterial populations have the metabolic capability to couple acetate oxidation to sequential reduction of electron acceptors which can reduce Cr(VI) to less mobile and toxic Cr(III), and that microbially produced sulfide may be important in reductive precipitation of chromate. This capability could be harnessed to create a Cr(VI) trap-zone beneath COPR tips without the need to disturb the waste.
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Affiliation(s)
- Douglas I Stewart
- School of Civil Engineering, University of Leeds, Leeds LS2 9JT, UK.
| | | | - Ian T Burke
- School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK.
| | - Alison Baker
- School of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, UK.
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Scuvée D, Goñi-Urriza M, Tessier E, Gassie C, Ranchou-Peyruse M, Amouroux D, Guyoneaud R, Khalfaoui-Hassani B. Molybdate inhibits mercury methylation capacity of Pseudodesulfovibrio hydrargyri BerOc1 regardless of the growth metabolism. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2024; 31:42686-42697. [PMID: 38878247 DOI: 10.1007/s11356-024-33901-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Accepted: 05/31/2024] [Indexed: 07/04/2024]
Abstract
Molybdate inhibits sulfate respiration in sulfate-reducing bacteria (SRB). It is used as an inhibitor to indirectly evaluate the role of SRB in mercury methylation in the environment. Here, the SRB Pseudodesulfovibrio hydrargyri BerOc1 was used to assess the effect of molybdate on cell growth and mercury methylation under various metabolic conditions. Geobacter sulfurreducens PCA was used as the non-SRB counterpart strain with the ability to methylate mercury. While PCA growth and methylation are not affected by molybdate, 1 mM of molybdate inhibits BerOc1 growth under sulfate respiration (50% inhibition) but also under fumarate respiration (complete inhibition). Even more surprising, mercury methylation of BerOc1 is totally inhibited at 0.1 mM of molybdate when grown under sulfate or fumarate respiration with pyruvate as the electron donor. As molybdate is expected to reduce cellular ATP level, the lower Hg methylation observed with pyruvate could be the consequence of lower energy production. Although molybdate alters the expression of hgcA (mercury methylation marker) and sat (involved in sulfate reduction and molybdate sensitivity) in a metabolism-dependent manner, no relationship with mercury methylation rates could be found. Our results show, for the first time, a specific mercury methylation inhibition by molybdate in SRB.
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Affiliation(s)
- Diva Scuvée
- Université de Pau et des Pays de l'Adour, E2S UPPA, CNRS, IPREM, Pau, France
| | - Marisol Goñi-Urriza
- Université de Pau et des Pays de l'Adour, E2S UPPA, CNRS, IPREM, Pau, France
| | - Emmanuel Tessier
- Université de Pau et des Pays de l'Adour, E2S UPPA, CNRS, IPREM, Pau, France
| | - Claire Gassie
- Université de Pau et des Pays de l'Adour, E2S UPPA, CNRS, IPREM, Pau, France
| | | | - David Amouroux
- Université de Pau et des Pays de l'Adour, E2S UPPA, CNRS, IPREM, Pau, France
| | - Rémy Guyoneaud
- Université de Pau et des Pays de l'Adour, E2S UPPA, CNRS, IPREM, Pau, France
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6
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Klein E, Wurst R, Rehnlund D, Gescher J. Elucidating the development of cooperative anode-biofilm-structures. Biofilm 2024; 7:100193. [PMID: 38601817 PMCID: PMC11004076 DOI: 10.1016/j.bioflm.2024.100193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Revised: 03/13/2024] [Accepted: 03/21/2024] [Indexed: 04/12/2024] Open
Abstract
Microbial electrochemical systems are a highly versatile platform technology with a particular focus on the interplay of chemical and electrical energy conversion and offer immense potential for a sustainable bioeconomy. The industrial realization of this potential requires a critical focus on biofilm optimization if performance is to be controlled over a long period of time. Moreover, the aspect and influence of cooperativity has to be addressed as many applied anodic bioelectrochemical systems will most likely be operated with a diversity of interacting microbial species. Hence, the aim of this study was to analyze how interspecies dependence and cooperativity of a model community influence the development of anodic biofilms. To investigate biofilm activity in a spatially resolved manner, a microfluidic bioelectrochemical flow cell was developed that can be equipped with user-defined electrode materials and operates under laminar flow conditions. With this infrastructure, the development of single and co-culture biofilms of the two model organisms Shewanella oneidensis and Geobacter sulfurreducens on graphite electrodes was monitored by optical coherence tomography analysis. The interdependence in the co-culture biofilm was achieved by feeding the community with lactate, which is converted by S. oneidensis into acetate, which in turn serves as substrate for G. sulfurreducens. The results show that co-cultivation resulted in the formation of denser biofilms than in single culture. Moreover, we hypothesize that S. oneidensis in return utilizes the conductive biofilm matrix build by G. sulfurreducens for direct interspecies electron transfer (DIET) to the anode. FISH analysis revealed that the biofilms consisted of approximately two-thirds G. sulfurreducens cells, which most likely formed a conductive 3D network throughout the biofilm matrix, in which evenly distributed tubular S. oneidensis colonies were embedded without direct contact to the anode surface. Live/dead staining shows that the outermost biofilm contained almost exclusively dead cells (98 %), layers near the anode contained 45-56 % and the entire biofilm contained 82 % live cells. Our results exemplify how the architecture of the exoelectrogenic biofilm dynamically adapts to the respective process conditions.
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Affiliation(s)
- Edina Klein
- Institute of Technical Microbiology, University of Technology Hamburg, Hamburg, Germany
| | - René Wurst
- Institute of Technical Microbiology, University of Technology Hamburg, Hamburg, Germany
| | - David Rehnlund
- Department of Chemistry – Ångström Laboratory, Uppsala University, Box 538, SE-751 21, Uppsala, Sweden
| | - Johannes Gescher
- Institute of Technical Microbiology, University of Technology Hamburg, Hamburg, Germany
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7
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Williamson AJ, Binet M, Sergeant C. Radionuclide biogeochemistry: from bioremediation toward the treatment of aqueous radioactive effluents. Crit Rev Biotechnol 2024; 44:698-716. [PMID: 37258417 DOI: 10.1080/07388551.2023.2194505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 10/07/2022] [Accepted: 01/29/2023] [Indexed: 06/02/2023]
Abstract
Civilian and military nuclear programs of several nations over more than 70 years have led to significant quantities of heterogenous solid, organic, and aqueous radioactive wastes bearing actinides, fission products, and activation products. While many physicochemical treatments have been developed to remediate, decontaminate and reduce waste volumes, they can involve high costs (energy input, expensive sorbants, ion exchange resins, chemical reducing/precipitation agents) or can lead to further secondary waste forms. Microorganisms can directly influence radionuclide solubility, via sorption, accumulation, precipitation, redox, and volatilization pathways, thus offering a more sustainable approach to remediation or effluent treatments. Much work to date has focused on fundamentals or laboratory-scale remediation trials, but there is a paucity of information toward field-scale bioremediation and, to a lesser extent, toward biological liquid effluent treatments. From the few biostimulation studies that have been conducted at legacy weapon production/test sites and uranium mining and milling sites, some marked success via bioreduction and biomineralisation has been observed. However, rebounding of radionuclide mobility from (a)biotic scale-up factors are often encountered. Radionuclide, heavy metal, co-contaminant, and/or matrix effects provide more challenging conditions than traditional industrial wastewater systems, thus innovative solutions via indirect interactions with stable element biogeochemical cycles, natural or engineered cultures or communities of metal and irradiation tolerant strains and reactor design inspirations from existing metal wastewater technologies, are required. This review encompasses the current state of the art in radionuclide biogeochemistry fundamentals and bioremediation and establishes links toward transitioning these concepts toward future radioactive effluent treatments.
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Affiliation(s)
| | - Marie Binet
- EDF R&D, LNHE (Laboratoire National d'Hydraulique et Environnement), Chatou, France
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8
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Rodríguez-Torres LM, Huerta-Miranda GA, Martínez-García AL, Mazón-Montijo DA, Hernández-Eligio A, Miranda-Hernández M, Juárez K. Influence of support materials on the electroactive behavior, structure and gene expression of wild type and GSU1771-deficient mutant of Geobacter sulfurreducens biofilms. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2024:10.1007/s11356-024-33612-3. [PMID: 38758442 DOI: 10.1007/s11356-024-33612-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Accepted: 05/05/2024] [Indexed: 05/18/2024]
Abstract
Geobacter sulfurreducens DL1 is a metal-reducing dissimilatory bacterium frequently used to produce electricity in bioelectrochemical systems (BES). The biofilm formed on electrodes is one of the most important factors for efficient electron transfer; this is possible due to the production of type IV pili and c-type cytochromes that allow it to carry out extracellular electron transfer (EET) to final acceptors. In this study, we analyzed the biofilm formed on different support materials (glass, hematite (Fe2O3) on glass, fluorine-doped tin oxide (FTO) semiconductor glass, Fe2O3 on FTO, graphite, and stainless steel) by G. sulfurreducens DL1 (WT) and GSU1771-deficient strain mutant (Δgsu1771). GSU1771 is a transcriptional regulator that controls the expression of several genes involved in electron transfer. Different approaches and experimental tests were carried out with the biofilms grown on the different support materials including structure analysis by confocal laser scanning microscopy (CLSM), characterization of electrochemical activity, and quantification of relative gene expression by RT-qPCR. The gene expression of selected genes involved in EET was analyzed, observing an overexpression of pgcA, omcS, omcM, and omcF from Δgsu1771 biofilms compared to those from WT, also the overexpression of the epsH gene, which is involved in exopolysaccharide synthesis. Although we observed that for the Δgsu1771 mutant strain, the associated redox processes are similar to the WT strain, and more current is produced, we think that this could be associated with a higher relative expression of certain genes involved in EET and in the production of exopolysaccharides despite the chemical environment where the biofilm develops. This study supports that G. sulfurreducens is capable of adapting to the electrochemical environment where it grows.
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Affiliation(s)
- Luis Miguel Rodríguez-Torres
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001. Col. Chamilpa, 62210, Cuernavaca, Morelos, México
| | - Guillermo Antonio Huerta-Miranda
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001. Col. Chamilpa, 62210, Cuernavaca, Morelos, México
| | - Ana Luisa Martínez-García
- Centro de Investigación en Materiales Avanzados S. C., Subsede Monterrey, Grupo de Investigación DORA-Lab, 66628, Apodaca, N. L, México
- Centro de Investigación e Innovación Tecnológica (CIIT), Grupo de Investigación DORA-Lab, Tecnológico Nacional de México Campus Nuevo León (TECNL), 66629, Apodaca, N. L, México
| | - Dalia Alejandra Mazón-Montijo
- Centro de Investigación en Materiales Avanzados S. C., Subsede Monterrey, Grupo de Investigación DORA-Lab, 66628, Apodaca, N. L, México
- Centro de Investigación e Innovación Tecnológica (CIIT), Grupo de Investigación DORA-Lab, Tecnológico Nacional de México Campus Nuevo León (TECNL), 66629, Apodaca, N. L, México
- Investigadores Por México, CONAHCYT, Ciudad de México, México
| | - Alberto Hernández-Eligio
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001. Col. Chamilpa, 62210, Cuernavaca, Morelos, México
- Investigadores Por México, CONAHCYT, Ciudad de México, México
| | - Margarita Miranda-Hernández
- Instituto de Energías Renovables, Universidad Nacional Autónoma de México, Priv. Xochicalco, 62580, Temixco, Morelos, México
| | - Katy Juárez
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001. Col. Chamilpa, 62210, Cuernavaca, Morelos, México.
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9
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Villa-Cruz V, Jaimes-Reátegui S, Alba-Cuevas JE, Zelaya-Molina LX, Jaimes-Reátegui R, Pisarchik AN. Quantifying Geobacter sulfurreducens growth: A mathematical model based on acetate concentration as an oxidizing substrate. MATHEMATICAL BIOSCIENCES AND ENGINEERING : MBE 2024; 21:5972-5995. [PMID: 38872566 DOI: 10.3934/mbe.2024263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2024]
Abstract
We developed a mathematical model to simulate dynamics associated with the proliferation of Geobacter and ultimately optimize cellular operation by analyzing the interaction of its components. The model comprises two segments: an initial part comprising a logistic form and a subsequent segment that incorporates acetate oxidation as a saturation term for the microbial nutrient medium. Given that four parameters can be obtained by minimizing the square root of the mean square error between experimental Geobacter growth and the mathematical model, the model underscores the importance of incorporating nonlinear terms. The determined parameter values closely align with experimental data, providing insights into the mechanisms that govern Geobacter proliferation. Furthermore, the model has been transformed into a scaleless equation with only two parameters to simplify the exploration of qualitative properties. This allowed us to conduct stability analysis of the fixed point and construct a co-dimension two bifurcation diagram.
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Affiliation(s)
- Virgínia Villa-Cruz
- Centro Universitario de los Lagos, Universidad de Guadalajara, Enrique Díaz de León 1144, Colonia Paseos de la Montaña, 47460 Lagos de Moreno, Jalisco, Mexico
| | - Sumaya Jaimes-Reátegui
- Universidad Nacional Hermilio Valdizán, Av. Universitaria, 601-607, Pilco Marca, C.P. 10003, Huánuco, Perú
| | - Juana E Alba-Cuevas
- Centro Universitario de los Lagos, Universidad de Guadalajara, Enrique Díaz de León 1144, Colonia Paseos de la Montaña, 47460 Lagos de Moreno, Jalisco, Mexico
| | - Lily Xochilt Zelaya-Molina
- Centro Nacional de Recursos Genéticos, Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias, Boulevard de la Biodiversidad No. 400, Rancho Las Cruces, CP 47600. Tepatitlán de Morelos, Jalisco, Mexico
| | - Rider Jaimes-Reátegui
- Centro Universitario de los Lagos, Universidad de Guadalajara, Enrique Díaz de León 1144, Colonia Paseos de la Montaña, 47460 Lagos de Moreno, Jalisco, Mexico
| | - Alexander N Pisarchik
- Center for Biomedical Technology, Universidad Politécnica de Madrid, Campus de Montegancedo, Pozuelo de Alarcón, 28223 Madrid, Spain
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10
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Zhuang X, Wang S, Wu S. Electron Transfer in the Biogeochemical Sulfur Cycle. Life (Basel) 2024; 14:591. [PMID: 38792612 PMCID: PMC11123123 DOI: 10.3390/life14050591] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Revised: 04/30/2024] [Accepted: 05/02/2024] [Indexed: 05/26/2024] Open
Abstract
Microorganisms are key players in the global biogeochemical sulfur cycle. Among them, some have garnered particular attention due to their electrical activity and ability to perform extracellular electron transfer. A growing body of research has highlighted their extensive phylogenetic and metabolic diversity, revealing their crucial roles in ecological processes. In this review, we delve into the electron transfer process between sulfate-reducing bacteria and anaerobic alkane-oxidizing archaea, which facilitates growth within syntrophic communities. Furthermore, we review the phenomenon of long-distance electron transfer and potential extracellular electron transfer in multicellular filamentous sulfur-oxidizing bacteria. These bacteria, with their vast application prospects and ecological significance, play a pivotal role in various ecological processes. Subsequently, we discuss the important role of the pili/cytochrome for electron transfer and presented cutting-edge approaches for exploring and studying electroactive microorganisms. This review provides a comprehensive overview of electroactive microorganisms participating in the biogeochemical sulfur cycle. By examining their electron transfer mechanisms, and the potential ecological and applied implications, we offer novel insights into microbial sulfur metabolism, thereby advancing applications in the development of sustainable bioelectronics materials and bioremediation technologies.
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Affiliation(s)
- Xuliang Zhuang
- Key Laboratory of Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; (X.Z.); (S.W.)
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China
- State Key Laboratory of Tibetan Plateau Earth System, Environment and Resources (TPESER), Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China
| | - Shijie Wang
- Key Laboratory of Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; (X.Z.); (S.W.)
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Shanghua Wu
- Key Laboratory of Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; (X.Z.); (S.W.)
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China
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11
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Eshun LE, Coker VS, Shaw S, Lloyd JR. Strategies for optimizing biovivianite production using dissimilatory Fe(III)-reducing bacteria. ENVIRONMENTAL RESEARCH 2024; 242:117667. [PMID: 37980994 DOI: 10.1016/j.envres.2023.117667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 11/06/2023] [Accepted: 11/13/2023] [Indexed: 11/21/2023]
Abstract
Vivianite (Fe3(PO4)2·8H2O), a sink for phosphorus, is a key mineralization product formed during the microbial reduction of phosphate-containing Fe(III) minerals in natural systems, and also in wastewater treatment where Fe(III)-minerals are used to remove phosphate. As biovivianite is a potentially useful Fe and P fertiliser, there is much interest in harnessing microbial biovivianite synthesis for circular economy applications. In this study, we investigated the factors that influence the formation of microbially-synthesized vivianite (biovivianite) under laboratory batch systems including the presence and absence of phosphate and electron shuttle, the buffer system, pH, and the type of Fe(III)-reducing bacteria (comparing Geobacter sulfurreducens and Shewanella putrefaciens). The rate of Fe(II) production, and its interactions with the residual Fe(III) and other oxyanions (e.g., phosphate and carbonate) were the main factors that controlled the rate and extent of biovivianite formation. Higher concentrations of phosphate (e.g., P/Fe = 1) in the presence of an electron shuttle, at an initial pH between 6 and 7, were needed for optimal biovivianite formation. Green rust, a key intermediate in biovivianite production, could be detected as an endpoint alongside vivianite and metavivianite (Fe2+Fe3+2(PO4)2.(OH)2.6H2O), in treatments with G. sulfurreducens and S. putrefaciens. However, XRD indicated that vivianite abundance was higher in experiments containing G. sulfurreducens, where it dominated. This study, therefore, shows that vivianite formation can be controlled to optimize yield during microbial processing of phosphate-loaded Fe(III) materials generated from water treatment processes.
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Affiliation(s)
- Lordina E Eshun
- University of Manchester, Department of Earth and Environmental Sciences, Geomicrobiology Group, Williamson Building, M13 9QQ, Oxford Road, Manchester, UK.
| | - Victoria S Coker
- University of Manchester, Department of Earth and Environmental Sciences, Geomicrobiology Group, Williamson Building, M13 9QQ, Oxford Road, Manchester, UK.
| | - Samuel Shaw
- University of Manchester, Department of Earth and Environmental Sciences, Geomicrobiology Group, Williamson Building, M13 9QQ, Oxford Road, Manchester, UK.
| | - Jonathan R Lloyd
- University of Manchester, Department of Earth and Environmental Sciences, Geomicrobiology Group, Williamson Building, M13 9QQ, Oxford Road, Manchester, UK.
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12
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Veerubhotla R, Marzocchi U. Examining the resistance and resilience of anode-respiring Shewanella oneidensis biohybrid using microsensors. CHEMOSPHERE 2024; 350:141109. [PMID: 38176592 DOI: 10.1016/j.chemosphere.2024.141109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 12/09/2023] [Accepted: 01/01/2024] [Indexed: 01/06/2024]
Abstract
Immobilizing electro-active microbes within polymer matrices (thereby forming biohybrids) is a promising approach to accelerate microbial attachment to electrodes and increase the biofilm robustness. However, little is known on the fine scale chemical environment that develops within the electro-active biohybrids. Herein, we develop a biohybrid by immobilizing a culture of Shewanella oneidensis MR1 in agar matrix on the surface of a graphite electrode poised at +0.25 V. The resulting bioanode (3-6 mm thick) was grown under anoxic conditions and produced a steady current of 40 μA. Oxygen and pH distribution within the biohybrid were characterized in-situ using microsensors. As Shewanella is a facultative aerobe, it will halt the current production in the presence of oxygen. Thus, in addition, we investigated the alteration of the microenvironment during and after aeration of the medium to evaluate the oxygen tolerance of the system. During aeration, oxygen was effectively consumed in the top layers of the biofilm, leaving a 400-900 μm thick anoxic zone on the anode surface, that sustained >60% of the initial current. Current production recovered to pre-oxic condition within 5 h after the aeration was stopped, showing that immobilization can promote both high resistance and resilience of the system. Despite the absence of strong buffering conditions, pH profiles indicated a maximum drop of 0.2 units across the biohybrid. Characterizing the chemical microenvironment helps to elucidate the mechanistic functioning of artificial biofilms and hold a great potential for the designing of future, more effective biohybrid electrodes.
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Affiliation(s)
- Ramya Veerubhotla
- Aarhus University Center for Water Technology WATEC, Department of Biology, Aarhus University, Denmark.
| | - Ugo Marzocchi
- Aarhus University Center for Water Technology WATEC, Department of Biology, Aarhus University, Denmark; Center for Electromicrobiology CEM, Department of Biology, Aarhus University, Denmark
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13
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Yang G, Lin C, Hou T, Wu X, Fang Y, Yao S, Zhuang L, Yuan Y. The survival strategy of direct interspecies electron transfer-capable coculture under electron donor-limited environments. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 908:168223. [PMID: 37926263 DOI: 10.1016/j.scitotenv.2023.168223] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Revised: 10/08/2023] [Accepted: 10/28/2023] [Indexed: 11/07/2023]
Abstract
Direct interspecies electron transfer (DIET) has been considered as an effective mechanism for interspecies electron exchange in microbial syntrophy. Understanding DIET-capable syntrophic associations under energy-limited environments is important because these conditions more closely approximate those found in natural subsurface environments than in the batch cultures in the laboratory. This study, investigated the metabolic dynamics and electron transfer mechanisms in DIET-capable syntrophic coculture of Geobacter metallireducens and Geobacter sulfurreducens under electron donor-limited condition. The wild-coculture and the mutant-coculture with a citrate synthase-deficient G. sulfurreducens exhibited similar rates of syntrophic metabolism under ethanol-limited and ethanol-replete conditions. Transcriptomic analyses revealed that, in the mutant-coculture in which interspecies electron exchange was the sole electron source for G. sulfurreducens, the transcription of genes associated with uptake hydrogenase in G. sulfurreducens were significantly repressed and thus DIET tended to be the preferred mode of interspecies electron exchange under electron donor-limited condition. To overcome electron donor limitation, c-type cytochromes in the coculture actively moved from outer membrane to extracellular environment, potentially via increased secretion of outer-membrane vesicles. These results suggested a preferred electron transfer mechanism for DIET-capable syntrophic communities' survival in the electron donor-limited environments, providing valuable insights into the biogeochemical processes mediated by DIET in natural and engineered environments.
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Affiliation(s)
- Guiqin Yang
- Guangdong Key Laboratory of Environmental Pollution and Health, School of Environment, Jinan University, Guangzhou 510632, China
| | - Canfen Lin
- Guangdong Key Laboratory of Environmental Pollution and Health, School of Environment, Jinan University, Guangzhou 510632, China
| | - Tiqun Hou
- Guangdong Key Laboratory of Environmental Pollution and Health, School of Environment, Jinan University, Guangzhou 510632, China
| | - Xian Wu
- Guangdong Key Laboratory of Environmental Pollution and Health, School of Environment, Jinan University, Guangzhou 510632, China
| | - Yanlun Fang
- Guangdong Key Laboratory of Environmental Pollution and Health, School of Environment, Jinan University, Guangzhou 510632, China
| | - Sijie Yao
- Guangdong Key Laboratory of Environmental Pollution and Health, School of Environment, Jinan University, Guangzhou 510632, China
| | - Li Zhuang
- Guangdong Key Laboratory of Environmental Pollution and Health, School of Environment, Jinan University, Guangzhou 510632, China.
| | - Yong Yuan
- Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, China
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14
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Liu X, Ye Y, Yang N, Cheng C, Rensing C, Jin C, Nealson KH, Zhou S. Nonelectroactive clostridium obtains extracellular electron transfer-capability after forming chimera with Geobacter. ISME COMMUNICATIONS 2024; 4:ycae058. [PMID: 38770058 PMCID: PMC11104457 DOI: 10.1093/ismeco/ycae058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Revised: 03/25/2024] [Accepted: 04/15/2024] [Indexed: 05/22/2024]
Abstract
Extracellular electron transfer (EET) of microorganisms is a major driver of the microbial growth and metabolism, including reactions involved in the cycling of C, N, and Fe in anaerobic environments such as soils and sediments. Understanding the mechanisms of EET, as well as knowing which organisms are EET-capable (or can become so) is fundamental to electromicrobiology and geomicrobiology. In general, Gram-positive bacteria very seldomly perform EET due to their thick non-conductive cell wall. Here, we report that a Gram-positive Clostridium intestinale (C.i) attained EET-capability for ethanol metabolism only after forming chimera with electroactive Geobacter sulfurreducens (G.s). Mechanism analyses demonstrated that the EET was possible after the cell fusion of the two species was achieved. Under these conditions, the ethanol metabolism pathway of C.i was integrated by the EET pathway of G.s, by which achieved the oxidation of ethanol for the subsequent reduction of extracellular electron acceptors in the coculture. Our study displays a new approach to perform EET for Gram-positive bacteria via recruiting the EET pathway of an electroactive bacterium, which suggests a previously unanticipated prevalence of EET in the microbial world. These findings also provide new perspectives to understand the energetic coupling between bacterial species and the ecology of interspecies mutualisms.
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Affiliation(s)
- Xing Liu
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Yin Ye
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Naiming Yang
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Chen Cheng
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Christopher Rensing
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Chao Jin
- School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou, Guangdong 510006, China
| | - Kenneth H Nealson
- Department of Earth Science & Biological Sciences, University of Southern California, Los Angeles, CA 91030, United States
| | - Shungui Zhou
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
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15
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Zhang Y, O'Loughlin EJ, Park SY, Kwon MJ. Effects of Fe(III) (hydr)oxide mineralogy on the development of microbial communities originating from soil, surface water, groundwater, and aerosols. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 905:166993. [PMID: 37717756 DOI: 10.1016/j.scitotenv.2023.166993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 09/09/2023] [Accepted: 09/09/2023] [Indexed: 09/19/2023]
Abstract
Microbial Fe(III) reduction is a key component of the iron cycle in natural environments. However, the susceptibility of Fe(III) (hydr)oxides to microbial reduction varies depending on the mineral's crystallinity, and the type of Fe(III) (hydr)oxide in turn will affect the composition of the microbial community. We created microcosm reactors with microbial communities from four different sources (soil, surface water, groundwater, and aerosols), three Fe(III) (hydr)oxides (lepidocrocite, goethite, and hematite) as electron acceptors, and acetate as an electron donor to investigate the shaping effect of Fe(III) mineral type on the development of microbial communities. During a 10-month incubation, changes in microbial community composition, Fe(III) reduction, and acetate utilization were monitored. Overall, there was greater reduction of lepidocrocite than of goethite and hematite, and the development of microbial communities originating from the same source diverged when supplied with different Fe(III) (hydr)oxides. Furthermore, each Fe(III) mineral was associated with unique taxa that emerged from different sources. This study illustrates the taxonomic diversity of Fe(III)-reducing microbes from a broad range of natural environments.
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Affiliation(s)
- Yidan Zhang
- Department of Earth and Environmental Sciences, Korea University, Seoul 02841, South Korea
| | - Edward J O'Loughlin
- Biosciences Division, Argonne National Laboratory, Lemont, IL 60439, United States
| | - Su-Young Park
- Department of Earth and Environmental Sciences, Korea University, Seoul 02841, South Korea
| | - Man Jae Kwon
- Department of Earth and Environmental Sciences, Korea University, Seoul 02841, South Korea.
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16
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Long M, Zhou C, Zheng X, Rittmann BE. Reduction of Chromate via Biotic and Abiotic Pathways in the Presence of Three Co-contaminating Electron Acceptors. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:21190-21199. [PMID: 38051765 DOI: 10.1021/acs.est.3c04812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/07/2023]
Abstract
Bioreduction of Cr(VI) to Cr(III) is a promising technology for removing Cr(VI), but Cr(VI) reduction alone cannot support microbial growth. This study investigated the reduction of Cr(VI) in the presence of three electron acceptors that typically coexist with Cr(VI): NO3-, SO42-, and Fe(III). All three systems could reduce Cr(VI) to Cr(III), but the fate of Cr, its impacts on reduction of the other acceptors, and its impact on the microbial community differed. Although Cr(VI) was continuously removed in the NO3--reduction systems, batch tests showed that denitrification was inhibited primarily through impeding nitrite reduction. The SO42- and Fe(III) reduction systems reduced Cr(VI) using a combination of biotic and abiotic processes. Across all three systems, the abundance of genera capable of reducing Cr(VI) increased following the introduction of Cr(VI). Conversely, the abundance of genera that cannot reduce or resist Cr(VI) decreased, leading to restructuring of the microbial community. Furthermore, the abundance of sulfide oxidizers and Fe(II) oxidizers substantially increased after the introduction of chromate. This study provides fundamental knowledge about how Cr(VI) bioreduction interacts with bioreductions of three other co-contaminating electron acceptors.
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Affiliation(s)
- Min Long
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China
- Biodesign Swette Center for Environmental Biotechnology, Arizona State University, Tempe, Arizona 85287, United States
| | - Chen Zhou
- Biodesign Swette Center for Environmental Biotechnology, Arizona State University, Tempe, Arizona 85287, United States
| | - Xiong Zheng
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China
| | - Bruce E Rittmann
- Biodesign Swette Center for Environmental Biotechnology, Arizona State University, Tempe, Arizona 85287, United States
- School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, Arizona 85287, United States
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17
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Yunda E, Phan Le QN, Björn E, Ramstedt M. Biochemical characterization and mercury methylation capacity of Geobacter sulfurreducens biofilms grown in media containing iron hydroxide or fumarate. Biofilm 2023; 6:100144. [PMID: 37583615 PMCID: PMC10424081 DOI: 10.1016/j.bioflm.2023.100144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 07/03/2023] [Accepted: 07/24/2023] [Indexed: 08/17/2023] Open
Abstract
Geobacter species are common in iron-rich environments and can contribute to formation of methylmercury (MeHg), a neurotoxic compound with high bioaccumulation potential formed as a result of bacterial and archaeal physiological activity. Geobacter sulfurreducens can utilize various electron acceptors for growth including iron hydroxides or fumarate. However, it remains poorly understood how the growth on these compounds affects physiological properties of bacterial cells in biofilms, including the capacity to produce MeHg. The purpose of this study was to determine changes in the biochemical composition of G. sulfurreducens during biofilm cultivation in media containing iron hydroxide or fumarate, and to quantify mercury (Hg) methylation capacity of the formed biofilms. Biofilms were characterized by Fourier-transform infrared spectroscopy in the attenuated total reflection mode (ATR-FTIR), Resonance Raman spectroscopy and confocal laser scanning microscopy. MeHg formation was quantified by mass spectrometry after incubation of biofilms with 100 nM Hg. The results of ATR-FTIR experiments showed that in presence of fumarate, G. sulfurreducens biofilm formation was accompanied by variation in content of the energy-reserve polymer glycogen over time, which could be cancelled by the addition of supplementary nutrients (yeast extract). In contrast, biofilms cultivated on Fe(III) hydroxide did not accumulate glycogen. The ATR-FTIR results further suggested that Fe(III) hydroxide surfaces bind cells via phosphate and carboxylate groups of bacteria that form complexes with iron. Furthermore, biofilms grown on Fe(III) hydroxide had higher fraction of oxidized cytochromes and produced two to three times less biomass compared to conditions with fumarate. Normalized to biofilm volume, the content of MeHg was similar in assays with biofilms grown on Fe(III) hydroxide and on fumarate (with yeast extract and without). These results suggest that G. sulfurreducens biofilms produce MeHg irrespectively from glycogen content and cytochrome redox state in the cells, and warrant further investigation of the mechanisms controlling this process.
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Affiliation(s)
- Elena Yunda
- Department of Chemistry, Umeå University, Sweden
| | | | - Erik Björn
- Department of Chemistry, Umeå University, Sweden
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18
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Aronson HS, Clark CE, LaRowe DE, Amend JP, Polerecky L, Macalady JL. Sulfur disproportionating microbial communities in a dynamic, microoxic-sulfidic karst system. GEOBIOLOGY 2023; 21:791-803. [PMID: 37721188 DOI: 10.1111/gbi.12574] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 07/24/2023] [Accepted: 08/29/2023] [Indexed: 09/19/2023]
Abstract
Biogeochemical sulfur cycling in sulfidic karst systems is largely driven by abiotic and biological sulfide oxidation, but the fate of elemental sulfur (S0 ) that accumulates in these systems is not well understood. The Frasassi Cave system (Italy) is intersected by a sulfidic aquifer that mixes with small quantities of oxygen-rich meteoric water, creating Proterozoic-like conditions and supporting a prolific ecosystem driven by sulfur-based chemolithoautotrophy. To better understand the cycling of S0 in this environment, we examined the geochemistry and microbiology of sediments underlying widespread sulfide-oxidizing mats dominated by Beggiatoa. Sediment populations were dominated by uncultivated relatives of sulfur cycling chemolithoautotrophs related to Sulfurovum, Halothiobacillus, Thiofaba, Thiovirga, Thiobacillus, and Desulfocapsa, as well as diverse uncultivated anaerobic heterotrophs affiliated with Bacteroidota, Anaerolineaceae, Lentimicrobiaceae, and Prolixibacteraceae. Desulfocapsa and Sulfurovum populations accounted for 12%-26% of sediment 16S rRNA amplicon sequences and were closely related to isolates which carry out autotrophic S0 disproportionation in pure culture. Gibbs energy (∆Gr ) calculations revealed that S0 disproportionation under in situ conditions is energy yielding. Microsensor profiles through the mat-sediment interface showed that Beggiatoa mats consume dissolved sulfide and oxygen, but a net increase in acidity was only observed in the sediments below. Together, these findings suggest that disproportionation is an important sink for S0 generated by microbial sulfide oxidation in this oxygen-limited system and may contribute to the weathering of carbonate rocks and sediments in sulfur-rich environments.
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Affiliation(s)
- Heidi S Aronson
- Department of Biological Sciences, University of Southern California, Los Angeles, California, USA
| | - Christian E Clark
- Department of Geosciences, Pennsylvania State University, University Park, Pennsylvania, USA
| | - Douglas E LaRowe
- Department of Earth Sciences, University of Southern California, Los Angeles, California, USA
| | - Jan P Amend
- Department of Biological Sciences, University of Southern California, Los Angeles, California, USA
- Department of Earth Sciences, University of Southern California, Los Angeles, California, USA
| | - Lubos Polerecky
- Department of Earth Sciences, Utrecht University, Utrecht, The Netherlands
| | - Jennifer L Macalady
- Department of Geosciences, Pennsylvania State University, University Park, Pennsylvania, USA
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19
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Jiang J, He P, Luo Y, Peng Z, Jiang Y, Hu Y, Qi L, Dong X, Dong Y, Shi L. The varied roles of pilA-N, omcE, omcS, omcT, and omcZ in extracellular electron transfer by Geobacter sulfurreducens. Front Microbiol 2023; 14:1251346. [PMID: 37881251 PMCID: PMC10597711 DOI: 10.3389/fmicb.2023.1251346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2023] [Accepted: 09/25/2023] [Indexed: 10/27/2023] Open
Abstract
Geobacter sulfurreducens mediates extracellular electron transfer (EET) reactions with different substrates, such as solid-phase Fe(III)-containing minerals, anodes and the cells of Geobacter metallireducens. To compare their roles in EET, the pilA-N, omcE, omcS, omcT and omcZ genes of G. sulfurreducens were systematically deleted. All mutants showed impaired and varied ability to form biofilms on nonconductive surface. Deletion of omcE also impaired bacterial ability to reduce ferrihydrite, but its impacts on the ability for anode reduction and the co-culture of G. metallireducens-G. sulfurreducens were minimal. The mutant without omcS showed diminished ability to reduce ferrihydrite and to form the co-culture, but was able to regain its ability to reduce anodes. Deletion of omcT, omcZ or pilA-N alone impaired bacterial ability to reduce ferrihydrite and anodes and to form the co-culture. Deletion of all tested genes abolished bacterial ability to reduce ferrihydrite and anodes. Triple-deletion of all omcS, omcT and omcZ abolished the ability of G. sulfurreducens to co-culture with G. metallireducens. However, deletion of only omcZ or pilA-N or both omcS and omcT abolished the ability of G. sulfurreducens without hydrogenase gene hybL to co-culture with G. metallireducens, which show their indispensable roles in direct electron transfer from G. metallireducens to G. sulfurreducens. Thus, the roles of pilA-N, omcE, omcS, omcT and omcZ for G. sulfurreducens in EET vary substantially, which also suggest that possession of PilA-N and multiple cytochromes of different structures enables G. sulfurreducens to mediate EET reactions efficiently with substrates of different properties.
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Affiliation(s)
- Jie Jiang
- School of Environmental Studies, China University of Geosciences-Wuhan, Wuhan, China
| | - Pengchen He
- School of Environmental Studies, China University of Geosciences-Wuhan, Wuhan, China
| | - Ying Luo
- School of Environmental Studies, China University of Geosciences-Wuhan, Wuhan, China
| | - Zhaofeng Peng
- School of Environmental Studies, China University of Geosciences-Wuhan, Wuhan, China
| | - Yongguang Jiang
- School of Environmental Studies, China University of Geosciences-Wuhan, Wuhan, China
| | - Yidan Hu
- School of Environmental Studies, China University of Geosciences-Wuhan, Wuhan, China
| | - Lei Qi
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Xiuzhu Dong
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Yiran Dong
- School of Environmental Studies, China University of Geosciences-Wuhan, Wuhan, China
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences-Wuhan, Wuhan, China
- State Environmental Protection Key Laboratory of Source Apportionment and Control of Aquatic Pollution, Ministry of Ecology and Environment, China University of Geosciences-Wuhan, Wuhan, China
- Hubei Key Laboratory of Yangtze Catchment Environmental Aquatic Science, China University of Geosciences-Wuhan, Wuhan, China
| | - Liang Shi
- School of Environmental Studies, China University of Geosciences-Wuhan, Wuhan, China
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences-Wuhan, Wuhan, China
- State Environmental Protection Key Laboratory of Source Apportionment and Control of Aquatic Pollution, Ministry of Ecology and Environment, China University of Geosciences-Wuhan, Wuhan, China
- Hubei Key Laboratory of Yangtze Catchment Environmental Aquatic Science, China University of Geosciences-Wuhan, Wuhan, China
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20
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Portela PC, Morgado L, Silva MA, Denkhaus L, Einsle O, Salgueiro CA. Exploring oxidative stress pathways in Geobacter sulfurreducens: the redox network between MacA peroxidase and triheme periplasmic cytochromes. Front Microbiol 2023; 14:1253114. [PMID: 37860142 PMCID: PMC10582990 DOI: 10.3389/fmicb.2023.1253114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Accepted: 09/11/2023] [Indexed: 10/21/2023] Open
Abstract
The recent reclassification of the strict anaerobe Geobacter sulfurreducens bacterium as aerotolerant brought attention for oxidative stress protection pathways. Although the electron transfer pathways for oxygen detoxification are not well established, evidence was obtained for the formation of a redox complex between the periplasmic triheme cytochrome PpcA and the diheme cytochrome peroxidase MacA. In the latter, the reduction of the high-potential heme triggers a conformational change that displaces the axial histidine of the low-potential heme with peroxidase activity. More recently, a possible involvement of the triheme periplasmic cytochrome family (PpcA-E) in the protection from oxidative stress in G. sulfurreducens was suggested. To evaluate this hypothesis, we investigated the electron transfer reaction and the biomolecular interaction between each PpcA-E cytochrome and MacA. Using a newly developed method that relies on the different NMR spectral signatures of the heme proteins, we directly monitored the electron transfer reaction from reduced PpcA-E cytochromes to oxidized MacA. The results obtained showed a complete electron transfer from the cytochromes to the high-potential heme of MacA. This highlights PpcA-E cytochromes' efficient role in providing the necessary reducing power to mitigate oxidative stress situations, hence contributing to a better knowledge of oxidative stress protection pathways in G. sulfurreducens.
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Affiliation(s)
- Pilar C. Portela
- Associate Laboratory i4HB – Institute for Health and Bioeconomy, NOVA School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal
- UCIBIO – Applied Molecular Biosciences Unit, Department of Chemistry, NOVA School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal
| | - Leonor Morgado
- Associate Laboratory i4HB – Institute for Health and Bioeconomy, NOVA School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal
- UCIBIO – Applied Molecular Biosciences Unit, Department of Chemistry, NOVA School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal
| | - Marta A. Silva
- Associate Laboratory i4HB – Institute for Health and Bioeconomy, NOVA School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal
- UCIBIO – Applied Molecular Biosciences Unit, Department of Chemistry, NOVA School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal
| | - Lukas Denkhaus
- Institut für Biochemie, Albert-Ludwigs-Universität, Freiburg, Germany
| | - Oliver Einsle
- Institut für Biochemie, Albert-Ludwigs-Universität, Freiburg, Germany
| | - Carlos A. Salgueiro
- Associate Laboratory i4HB – Institute for Health and Bioeconomy, NOVA School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal
- UCIBIO – Applied Molecular Biosciences Unit, Department of Chemistry, NOVA School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal
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21
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Peco JD, Thouin H, Esbrí JM, Campos-Rodríguez HR, García-Noguero EM, Breeze D, Villena J, Gloaguen E, Higueras PL, Battaglia-Brunet F. Mobility of antimony in contrasting surface environments of a mine site: influence of redox conditions and microbial communities. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:105808-105828. [PMID: 37721674 DOI: 10.1007/s11356-023-29734-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Accepted: 09/02/2023] [Indexed: 09/19/2023]
Abstract
Microbial processes can influence the complex geochemical behaviour of the toxic metalloid antimony (Sb) in mining environments. The present study is aimed to evaluate the influence of microbial communities on the mobility of Sb from solid phases to water in different compartments and redox conditions of a mining site in southwest (SW) Spain. Samples of surface materials presenting high Sb concentrations, from two weathered mining waste dumps, and an aquatic sediment were incubated in slurries comparing oxic and anoxic conditions. The initial microbial communities of the three materials strongly differed. Incubations induced an increase of microbial biomass and an evolution of the microbial communities' structures and compositions, which diverged in different redox conditions. The presence of active bacteria always influenced the mobility of Sb, except in the neutral pH waste incubated in oxic conditions. The effect of active microbial activities in oxic conditions was dependent on the material: Sb oxic release was biologically amplified with the acidic waste, but attenuated with the sediment. Different bacterial genera involved in Sb, Fe and S oxidation or reduction were present and/or grew during incubation of each material. The results highlighted the wide diversity of microbial communities and metabolisms at the small geographic scale of a mining site and their strong implication in Sb mobility.
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Affiliation(s)
- Jesús Daniel Peco
- Instituto de Geología Aplicada, Escuela Universitaria Politécnica de Almadén, Universidad de Castilla-La Mancha, Plaza Manuel Meca, Ciudad Real, 13400, Almadén, Spain
- Escuela Técnica Superior de Ingenieros Agrónomos de Ciudad Real, Universidad de Castilla-La Mancha, Ronda de Calatrava 7, 13071, Ciudad Real, Spain
| | - Hugues Thouin
- BRGM, 3 Av. Claude Guillemin, 45060, Orléans, France
| | - José María Esbrí
- Departamento de Mineralogía y Petrología, Facultad de Ciencias Geológicas, Universidad Complutense de Madrid, 28040, Madrid, Spain
| | | | - Eva Maria García-Noguero
- Instituto de Geología Aplicada, Escuela Universitaria Politécnica de Almadén, Universidad de Castilla-La Mancha, Plaza Manuel Meca, Ciudad Real, 13400, Almadén, Spain
| | | | - Jaime Villena
- Escuela Técnica Superior de Ingenieros Agrónomos de Ciudad Real, Universidad de Castilla-La Mancha, Ronda de Calatrava 7, 13071, Ciudad Real, Spain
| | - Eric Gloaguen
- CNRS, BRGM, ISTO, UMR 7327, Université d'Orléans, 45071, Orléans, France
| | - Pablo Leon Higueras
- Instituto de Geología Aplicada, Escuela Universitaria Politécnica de Almadén, Universidad de Castilla-La Mancha, Plaza Manuel Meca, Ciudad Real, 13400, Almadén, Spain
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22
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Ochiai I, Harada T, Jomori S, Kouzuma A, Watanabe K. Bioaugmentation of microbial electrolysis cells with Geobacter sulfurreducens YM18 for enhanced hydrogen production from starch. BIORESOURCE TECHNOLOGY 2023; 386:129508. [PMID: 37468016 DOI: 10.1016/j.biortech.2023.129508] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 07/12/2023] [Accepted: 07/16/2023] [Indexed: 07/21/2023]
Abstract
Double-chamber microbial electrolysis cells (MECs) were operated using starch-based medium as the anolyte and rice paddy-field soil as the anode inoculum, and hydrogen production from the cathode chamber was examined. In order to enhance current generation and hydrogen production, the anode chamber was bioaugmented with Geobacter sulfurreducens strain YM18, and its effects were evaluated based on the performances of non-bioaugmented controls. Results show that the bioaugmented MEC generated threefold greater current during one-month operation and produced sixfold greater amounts of hydrogen than those of the non-bioaugmented control. Quantitative PCR and metabarcoding analyses confirmed successful colonization of anode surfaces with YM18, suggesting the utility of bioaugmentation with YM18 for enhancing the performance of bioelectrochemical systems, including MECs treating biomass wastes.
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Affiliation(s)
- Itta Ochiai
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan
| | - Tomoka Harada
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan
| | - Shinji Jomori
- Advanced Material Engineering Division, Toyota Motor Corporation, Susono, Shizuoka 410-1193, Japan
| | - Atsushi Kouzuma
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan
| | - Kazuya Watanabe
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan.
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23
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Howley E, Krajmalnik-Brown R, Torres CI. Cytochrome gene expression shifts in Geobacter sulfurreducens to maximize energy conservation in response to changes in redox conditions. Biosens Bioelectron 2023; 237:115524. [PMID: 37459687 DOI: 10.1016/j.bios.2023.115524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 06/19/2023] [Accepted: 07/07/2023] [Indexed: 08/13/2023]
Abstract
Previous studies have identified that Geobacter sulfurreducens has three different electron transfer pathways for respiration, and it switches between these pathways to adapt to the redox potential of its electron acceptor. However, only a small fraction of the electron carriers from each pathway have been identified. In this study, we combined electrochemical and gene expression data to identify electron carriers in the inner membrane, periplasm, outer membrane, and exterior of the cell that may be induced by the use of the three different electron transfer pathways. Cyclic voltammetry was performed on thin biofilms grown on anodes poised at different redox potentials, providing a quantitative assessment of the relative use of three electron-transfer pathways in each condition (catalytic midpoint potentials (EKAs) of -0.227 V [Low], -0.15 V [Medium], -0.1 V [High] vs. SHE). Transcriptomic analyses as a function of electrochemical signals or fumarate utilization showed differential induction in inner membrane (Medium: cbcL), periplasmic (Low: ppcB/ppcE, Medium: ppcA), outer membrane (Low: extA/extC, Medium: extJ/extK, Fumarate: extF/extG), and extracellular (Medium: omcZ, High/Fumarate: omcS/omcT) cytochromes, suggesting the pathway signals are associated with complex transcriptomic responses in genes across the electron transfer pathway. Our method combining electrochemical modeling and transcriptomics could be adapted to better understand electron transport in other electroactive organisms with complex metabolisms.
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Affiliation(s)
- Ethan Howley
- Biodesign Swette Center for Environmental Biotechnology, Arizona State University, Tempe, AZ, USA; School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, AZ, USA
| | - Rosa Krajmalnik-Brown
- School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, AZ, USA; Biodesign Center for Health Through Microbiomes, Arizona State University, Tempe, AZ, USA
| | - César I Torres
- Biodesign Swette Center for Environmental Biotechnology, Arizona State University, Tempe, AZ, USA; School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ, USA.
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24
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Ni Z, Zhou L, Lin Z, Kuang B, Zhu G, Jia J, Wang T. Iron-modified biochar boosts anaerobic digestion of sulfamethoxazole pharmaceutical wastewater: Performance and microbial mechanism. JOURNAL OF HAZARDOUS MATERIALS 2023; 452:131314. [PMID: 37030222 DOI: 10.1016/j.jhazmat.2023.131314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/25/2022] [Revised: 02/26/2023] [Accepted: 03/26/2023] [Indexed: 05/03/2023]
Abstract
The accumulation of volatile fatty acids (VFAs) caused by antibiotic inhibition significantly reduces the treatment efficiency of sulfamethoxazole (SMX) wastewater. Few studies have been conducted to study the VFAs gradient metabolism of extracellular respiratory bacteria (ERB) and hydrogenotrophic methanogen (HM) under high-concentration sulfonamide antibiotics (SAs). And the effects of iron-modified biochar on antibiotics are unknown. Here, the iron-modified biochar was added to an anaerobic baffled reactor (ABR) to intensify the anaerobic digestion of SMX pharmaceutical wastewater. The results demonstrated that ERB and HM were developed after adding iron-modified biochar, promoting the degradation of butyric, propionic and acetic acids. The content of VFAs reduced from 1166.0 mg L-1 to 291.5 mg L-1. Therefore, chemical oxygen demand (COD) and SMX removal efficiency were improved by 22.76% and 36.51%, and methane production was enhanced by 6.19 times. Furthermore, the antibiotic resistance genes (ARGs) such as sul1, sul2, intl1 in effluent were decreased by 39.31%, 43.33%, 44.11%. AUTHM297 (18.07%), Methanobacterium (16.05%), Geobacter (6.05%) were enriched after enhancement. The net energy after enhancement was 0.7122 kWh m-3. These results confirmed that ERB and HM were enriched via iron-modified biochar to achieve high efficiency of SMX wastewater treatment.
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Affiliation(s)
- Zhili Ni
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen 529020, PR China
| | - Lilin Zhou
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen 529020, PR China
| | - Ziyang Lin
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen 529020, PR China
| | - Bin Kuang
- Jiangmen Polytechnic, Jiangmen 529020, PR China; Department of Civil and Environmental Engineering, University of Surrey, Surrey GU2 7XH, United Kingdom
| | - Gefu Zhu
- School of Environment and Nature Resources, Renmin University of China, Beijing 100872, PR China
| | - Jianbo Jia
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen 529020, PR China.
| | - Tao Wang
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen 529020, PR China.
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25
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Gutensohn M, Schaefer JK, Yunda E, Skyllberg U, Björn E. The Combined Effect of Hg(II) Speciation, Thiol Metabolism, and Cell Physiology on Methylmercury Formation by Geobacter sulfurreducens. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:7185-7195. [PMID: 37098211 PMCID: PMC10173453 DOI: 10.1021/acs.est.3c00226] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The chemical and biological factors controlling microbial formation of methylmercury (MeHg) are widely studied separately, but the combined effects of these factors are largely unknown. We examined how the chemical speciation of divalent, inorganic mercury (Hg(II)), as controlled by low-molecular-mass thiols, and cell physiology govern MeHg formation by Geobacter sulfurreducens. We compared MeHg formation with and without addition of exogenous cysteine (Cys) to experimental assays with varying nutrient and bacterial metabolite concentrations. Cysteine additions initially (0-2 h) enhanced MeHg formation by two mechanisms: (i) altering the Hg(II) partitioning from the cellular to the dissolved phase and/or (ii) shifting the chemical speciation of dissolved Hg(II) in favor of the Hg(Cys)2 complex. Nutrient additions increased MeHg formation by enhancing cell metabolism. These two effects were, however, not additive since cysteine was largely metabolized to penicillamine (PEN) over time at a rate that increased with nutrient addition. These processes shifted the speciation of dissolved Hg(II) from complexes with relatively high availability, Hg(Cys)2, to complexes with lower availability, Hg(PEN)2, for methylation. This thiol conversion by the cells thereby contributed to stalled MeHg formation after 2-6 h Hg(II) exposure. Overall, our results showed a complex influence of thiol metabolism on microbial MeHg formation and suggest that the conversion of cysteine to penicillamine may partly suppress MeHg formation in cysteine-rich environments like natural biofilms.
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Affiliation(s)
| | - Jeffra K Schaefer
- Department of Environmental Sciences, Rutgers University, 14 College Farm Road, New Brunswick, New Jersey 08901, United States
| | - Elena Yunda
- Department of Chemistry, Umeå University, SE- 90187 Umeå, Sweden
| | - Ulf Skyllberg
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden
| | - Erik Björn
- Department of Chemistry, Umeå University, SE- 90187 Umeå, Sweden
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26
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Chen S, Chen J, Zhang L, Huang S, Liu X, Yang Y, Luan T, Zhou S, Nealson KH, Rensing C. Biophotoelectrochemical process co-driven by dead microalgae and live bacteria. THE ISME JOURNAL 2023; 17:712-719. [PMID: 36823233 PMCID: PMC10119253 DOI: 10.1038/s41396-023-01383-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2022] [Revised: 02/08/2023] [Accepted: 02/10/2023] [Indexed: 02/25/2023]
Abstract
Anaerobic reduction processes in natural waters can be promoted by dead microalgae that have been attributed to nutrient substances provided by the decomposition of dead microalgae for other microorganisms. However, previous reports have not considered that dead microalgae may also serve as photosensitizers to drive microbial reduction processes. Here we demonstrate a photoelectric synergistic linkage between dead microalgae and bacteria capable of extracellular electron transfer (EET). Illumination of dead Raphidocelis subcapitata resulted in two-fold increase in the rate of anaerobic bioreduction by pure Geobacter sulfurreducens, suggesting that photoelectrons generated from the illuminated dead microalgae were transferred to the EET-capable microorganisms. Similar phenomena were observed in NO3- reduction driven by irradiated dead Chlorella vulgaris and living Shewanella oneidensis, and Cr(VI) reduction driven by irradiated dead Raphidocelis subcapitata and living Bacillus subtilis. Enhancement of bioreduction was also seen when the killed microalgae were illuminated in mixed-culture lake water, suggesting that EET-capable bacteria were naturally present and this phenomenon is common in post-bloom systems. The intracellular ferredoxin-NADP+-reductase is inactivated in the dead microalgae, allowing the production and extracellular transfer of photoelectrons. The use of mutant strains confirmed that the electron transport pathway requires multiheme cytochromes. Taken together, these results suggest a heretofore overlooked biophotoelectrochemical process jointly mediated by illumination of dead microalgae and live EET-capable bacteria in natural ecosystems, which may add an important component in the energetics of bioreduction phenomena particularly in microalgae-enriched environments.
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Affiliation(s)
- Shanshan Chen
- Guangdong Provincial Key Laboratory of Water Quality Improvement and Ecological Restoration for Watersheds, School of Ecology, Environment and Resources, Guangdong University of Technology, Guangzhou, China
| | - Jin Chen
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Lanlan Zhang
- Guangdong Provincial Key Laboratory of Water Quality Improvement and Ecological Restoration for Watersheds, School of Ecology, Environment and Resources, Guangdong University of Technology, Guangzhou, China
| | - Shaofu Huang
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Xing Liu
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Yuting Yang
- Guangdong Provincial Key Laboratory of Water Quality Improvement and Ecological Restoration for Watersheds, School of Ecology, Environment and Resources, Guangdong University of Technology, Guangzhou, China
| | - Tiangang Luan
- Guangdong Provincial Key Laboratory of Water Quality Improvement and Ecological Restoration for Watersheds, School of Ecology, Environment and Resources, Guangdong University of Technology, Guangzhou, China
| | - Shungui Zhou
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China.
| | - Kenneth H Nealson
- Department of Earth Science, University of Southern California, Los Angeles, CA, USA
| | - Christopher Rensing
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
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27
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Zhao Q, Liu Y, Liao C, Yan X, Tian L, Li T, Li N, Wang X. Reduction of S 0 deposited on electroactive biofilm under an oxidative potential. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 882:163698. [PMID: 37094684 DOI: 10.1016/j.scitotenv.2023.163698] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 04/13/2023] [Accepted: 04/19/2023] [Indexed: 05/03/2023]
Abstract
The inevitable deposition of S0 on the electroactive biofilm (EAB) via anodic sulfide oxidation affects the stability of bioelectrochemical systems (BESs) when an accidental discharge of sulfide occurred, leading to the inhibition of electroacitivity, because the potential of anode (e.g., 0 V versus Ag/AgCl) is ~500 mV more positive than the redox potential of S2-/S0. Here we found that S0 deposited on the EAB can be spontaneously reduced under this oxidative potential independent of microbial community variation, leading to a self-recovery of electroactivity (> 100 % in current density) with biofilm thickening (~210 μm). Transcriptomics of pure culture indicated that Geobacter highly expressed genes involving in S0 metabolism, which had an additional benefit to improve the viability (25 % - 36 %) of bacterial cells in biofilm distant from the anode and the cellular metabolic activity via electron shuttle pair of S0/S2-(Sx2-). Our findings highlighted the importance of spatially heterogeneous metabolism to its stability when EABs encountered with the problem of S0 deposition, and that in turn improved the electroactivity of EABs.
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Affiliation(s)
- Qian Zhao
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China
| | - Ying Liu
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China
| | - Chengmei Liao
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China
| | - Xuejun Yan
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China
| | - Lili Tian
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China
| | - Tian Li
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China
| | - Nan Li
- School of Environmental Science and Engineering, Tianjin University, No. 135 Yaguan Road, Jinnan District, Tianjin 300350, China
| | - Xin Wang
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China.
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28
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Shi K, Cheng H, Cornell CR, Wu H, Gao S, Jiang J, Liu T, Wang A, Zhou J, Liang B. Micro-aeration assisted with electrogenic respiration enhanced the microbial catabolism and ammonification of aromatic amines in industrial wastewater. JOURNAL OF HAZARDOUS MATERIALS 2023; 448:130943. [PMID: 36860074 DOI: 10.1016/j.jhazmat.2023.130943] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Revised: 01/29/2023] [Accepted: 02/03/2023] [Indexed: 06/18/2023]
Abstract
Improvement of refractory nitrogen-containing organics biodegradation is crucial to meet discharged nitrogen standards and guarantee aquatic ecology safety. Although electrostimulation accelerates organic nitrogen pollutants amination, it remains uncertain how to strengthen ammonification of the amination products. This study demonstrated that ammonification was remarkably facilitated under micro-aerobic conditions through the degradation of aniline, an amination product of nitrobenzene, using an electrogenic respiration system. The microbial catabolism and ammonification were significantly enhanced by exposing the bioanode to air. Based on 16S rRNA gene sequencing and GeoChip analysis, our results indicated that aerobic aniline degraders and electroactive bacteria were enriched in suspension and inner electrode biofilm, respectively. The suspension community had a significantly higher relative abundance of catechol dioxygenase genes contributing to aerobic aniline biodegradation and reactive oxygen species (ROS) scavenger genes to protect from oxygen toxicity. The inner biofilm community contained obviously higher cytochrome c genes responsible for extracellular electron transfer. Additionally, network analysis indicated the aniline degraders were positively associated with electroactive bacteria and could be the potential hosts for genes encoding for dioxygenase and cytochrome, respectively. This study provides a feasible strategy to enhance nitrogen-containing organics ammonification and offers new insights into the microbial interaction mechanisms of micro-aeration assisted with electrogenic respiration.
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Affiliation(s)
- Ke Shi
- State Key Laboratory of Urban Water Resource and Environment, Shenzhen Key Laboratory of Organic Pollution Prevention and Control, School of Civil & Environmental Engineering, Harbin Institute of Technology Shenzhen, Shenzhen 518055, China
| | - Haoyi Cheng
- State Key Laboratory of Urban Water Resource and Environment, Shenzhen Key Laboratory of Organic Pollution Prevention and Control, School of Civil & Environmental Engineering, Harbin Institute of Technology Shenzhen, Shenzhen 518055, China
| | - Carolyn R Cornell
- Department of Civil and Environmental Engineering, Rice University, Houston, TX 77005, USA
| | - Haiwei Wu
- State Key Laboratory of Urban Water Resource and Environment, Shenzhen Key Laboratory of Organic Pollution Prevention and Control, School of Civil & Environmental Engineering, Harbin Institute of Technology Shenzhen, Shenzhen 518055, China
| | - Shuhong Gao
- State Key Laboratory of Urban Water Resource and Environment, Shenzhen Key Laboratory of Organic Pollution Prevention and Control, School of Civil & Environmental Engineering, Harbin Institute of Technology Shenzhen, Shenzhen 518055, China
| | - Jiandong Jiang
- Key Lab of Agricultural Environmental Microbiology, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, 210095 Nanjing, China
| | - Tiejun Liu
- State Key Laboratory of Urban Water Resource and Environment, Shenzhen Key Laboratory of Organic Pollution Prevention and Control, School of Civil & Environmental Engineering, Harbin Institute of Technology Shenzhen, Shenzhen 518055, China
| | - Aijie Wang
- State Key Laboratory of Urban Water Resource and Environment, Shenzhen Key Laboratory of Organic Pollution Prevention and Control, School of Civil & Environmental Engineering, Harbin Institute of Technology Shenzhen, Shenzhen 518055, China
| | - Jizhong Zhou
- Institute for Environmental Genomics and Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK 73019, USA; School of Civil Engineering and Environmental Sciences, University of Oklahoma, Norman, OK 73019, USA; School of Computer Science, University of Oklahoma, Norman, OK 73019, USA; Earth and Environmental Sciences, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Bin Liang
- State Key Laboratory of Urban Water Resource and Environment, Shenzhen Key Laboratory of Organic Pollution Prevention and Control, School of Civil & Environmental Engineering, Harbin Institute of Technology Shenzhen, Shenzhen 518055, China.
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29
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Howley E, Mangus A, Williams D, Torres CI. Intracytoplasmic membranes develop in Geobacter sulfurreducens under thermodynamically limiting conditions. NPJ Biofilms Microbiomes 2023; 9:18. [PMID: 37029136 PMCID: PMC10082016 DOI: 10.1038/s41522-023-00384-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Accepted: 03/17/2023] [Indexed: 04/09/2023] Open
Abstract
Geobacter sulfurreducens is an electroactive bacterium capable of reducing metal oxides in the environment and electrodes in engineered systems1,2. Geobacter sp. are the keystone organisms in electrogenic biofilms, as their respiration consumes fermentation products produced by other organisms and reduces a terminal electron acceptor e.g. iron oxide or an electrode. To respire extracellular electron acceptors with a wide range of redox potentials, G. sulfurreducens has a complex network of respiratory proteins, many of which are membrane-bound3-5. We have identified intracytoplasmic membrane (ICM) structures in G. sulfurreducens. This ICM is an invagination of the inner membrane that has folded and organized by an unknown mechanism, often but not always located near the tip of a cell. Using confocal microscopy, we can identify that at least half of the cells contain an ICM when grown on low potential anode surfaces, whereas cells grown at higher potential anode surfaces or using fumarate as electron acceptor had significantly lower ICM frequency. 3D models developed from cryo-electron tomograms show the ICM to be a continuous extension of the inner membrane in contact with the cytoplasmic and periplasmic space. The differential abundance of ICM in cells grown under different thermodynamic conditions supports the hypothesis that it is an adaptation to limited energy availability, as an increase in membrane-bound respiratory proteins could increase electron flux. Thus, the ICM provides extra inner-membrane surface to increase the abundance of these proteins. G. sulfurreducens is the first Thermodesulfobacterium or metal-oxide reducer found to produce ICMs.
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Affiliation(s)
- Ethan Howley
- School for Sustainable Engineering and the Built Environment, Arizona State University, Tempe, AZ, USA
| | - Anna Mangus
- School for Engineering Mass Transport and Energy, Arizona State University, Tempe, AZ, USA
| | - Dewight Williams
- Eyring Materials Center, Arizona State University, Tempe, AZ, USA
| | - César I Torres
- School for Engineering Mass Transport and Energy, Arizona State University, Tempe, AZ, USA.
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Fan K, Wang W, Xu X, Yuan Y, Ren N, Lee DJ, Chen C. Recent Advances in Biotechnologies for the Treatment of Environmental Pollutants Based on Reactive Sulfur Species. Antioxidants (Basel) 2023; 12:antiox12030767. [PMID: 36979016 PMCID: PMC10044940 DOI: 10.3390/antiox12030767] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 03/19/2023] [Accepted: 03/20/2023] [Indexed: 03/30/2023] Open
Abstract
The definition of reactive sulfur species (RSS) is inspired by the reactivity and variable chemical valence of sulfur. Sulfur is an essential element for life and is a part of global geochemical cycles. Wastewater treatment bioreactors can be divided into two major categories: sulfur reduction and sulfur oxidation. We review the origins of the definition of RSS and related biotechnological processes in environmental management. Sulfate reduction, sulfide oxidation, and sulfur-based redox reactions are key to driving the coupled global carbon, nitrogen, and sulfur co-cycles. This shows the coupling of the sulfur cycle with the carbon and nitrogen cycles and provides insights into the global material-chemical cycle. We also review the biological classification and RSS metabolic mechanisms of functional microorganisms involved in the biological processes, such as sulfate-reducing and sulfur-oxidizing bacteria. Developments in molecular biology and genomic technologies have allowed us to obtain detailed information on these bacteria. The importance of RSS in environmental technologies requires further consideration.
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Affiliation(s)
- Kaili Fan
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Wei Wang
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Xijun Xu
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Yuan Yuan
- College of Biological Engineering, Beijing Polytechnic, Beijing 100176, China
| | - Nanqi Ren
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Duu-Jong Lee
- Department of Chemical Engineering, National Taiwan University, Taipei 106, Taiwan
| | - Chuan Chen
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
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Schneider G, Pásztor D, Szabó P, Kőrösi L, Kishan NS, Raju PARK, Calay RK. Isolation and Characterisation of Electrogenic Bacteria from Mud Samples. Microorganisms 2023; 11:microorganisms11030781. [PMID: 36985354 PMCID: PMC10058994 DOI: 10.3390/microorganisms11030781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 03/14/2023] [Accepted: 03/15/2023] [Indexed: 03/30/2023] Open
Abstract
To develop efficient microbial fuel cell systems for green energy production using different waste products, establishing characterised bacterial consortia is necessary. In this study, bacteria with electrogenic potentials were isolated from mud samples and examined to determine biofilm-formation capacities and macromolecule degradation. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry identifications have revealed that isolates represented 18 known and 4 unknown genuses. They all had the capacities to reduce the Reactive Black 5 stain in the agar medium, and 48 of them were positive in the wolfram nanorod reduction assay. The isolates formed biofilm to different extents on the surfaces of both adhesive and non-adhesive 96-well polystyrene plates and glass. Scanning electron microscopy images revealed the different adhesion potentials of isolates to the surface of carbon tissue fibres. Eight of them (15%) were able to form massive amounts of biofilm in three days at 23 °C. A total of 70% of the isolates produced proteases, while lipase and amylase production was lower, at 38% and 27% respectively. All of the macromolecule-degrading enzymes were produced by 11 isolates, and two isolates of them had the capacity to form a strong biofilm on the carbon tissue one of the most used anodic materials in MFC systems. This study discusses the potential of the isolates for future MFC development applications.
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Affiliation(s)
- György Schneider
- Department of Medical Microbiology and Immunology, Medical School, University of Pécs, Szigeti Str. 12, H-7624 Pécs, Hungary
| | - Dorina Pásztor
- Department of Medical Microbiology and Immunology, Medical School, University of Pécs, Szigeti Str. 12, H-7624 Pécs, Hungary
| | - Péter Szabó
- Department of Geology and Meteorology, Faculty of Sciences, University of Pécs, Ifjúság Str. 6, H-7624 Pécs, Hungary
| | - László Kőrösi
- Research Institute for Viticulture and Oenology, University of Pécs, Pázmány P. u. 4, H-7634 Pécs, Hungary
| | - Nandyala Siva Kishan
- Centre for Research and Development, SRKR Engineering College, SRKR Marg, China Amiram, Bhimavaram 534204, India
| | | | - Rajnish Kaur Calay
- Institute for Building Energy and Materials Technology, Narvik Campus, UiT Norway's Arctic University, 8514 Narvik, Norway
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Fessler M, Madsen JS, Zhang Y. Conjugative plasmids inhibit extracellular electron transfer in Geobacter sulfurreducens. Front Microbiol 2023; 14:1150091. [PMID: 37007462 PMCID: PMC10063792 DOI: 10.3389/fmicb.2023.1150091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Accepted: 02/20/2023] [Indexed: 03/19/2023] Open
Abstract
Geobacter sulfurreducens is part of a specialized group of microbes with the unique ability to exchange electrons with insoluble materials, such as iron oxides and electrodes. Therefore, G. sulfurreducens plays an essential role in the biogeochemical iron cycle and microbial electrochemical systems. In G. sulfurreducens this ability is primarily dependent on electrically conductive nanowires that link internal electron flow from metabolism to solid electron acceptors in the extracellular environment. Here we show that when carrying conjugative plasmids, which are self-transmissible plasmids that are ubiquitous in environmental bacteria, G. sulfurreducens reduces insoluble iron oxides at much slower rates. This was the case for all three conjugative plasmids tested (pKJK5, RP4 and pB10). Growth with electron acceptors that do not require expression of nanowires was, on the other hand, unaffected. Furthermore, iron oxide reduction was also inhibited in Geobacter chapellei, but not in Shewanella oneidensis where electron export is nanowire-independent. As determined by transcriptomics, presence of pKJK5 reduces transcription of several genes that have been shown to be implicated in extracellular electron transfer in G. sulfurreducens, including pilA and omcE. These results suggest that conjugative plasmids can in fact be very disadvantageous for the bacterial host by imposing specific phenotypic changes, and that these plasmids may contribute to shaping the microbial composition in electrode-respiring biofilms in microbial electrochemical reactors.
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Affiliation(s)
- Mathias Fessler
- Department of Environmental and Resource Engineering, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Jonas Stenløkke Madsen
- Section of Microbiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Yifeng Zhang
- Department of Environmental and Resource Engineering, Technical University of Denmark, Kongens Lyngby, Denmark
- *Correspondence: Yifeng Zhang,
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Yang Y, Wang J, Chen M, Li N, Yan J, Wang X. Self-forming electroactive dynamic membrane for enhancing the decolorization of methyl orange by weak electrical stimulation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 863:160897. [PMID: 36521609 DOI: 10.1016/j.scitotenv.2022.160897] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 12/08/2022] [Accepted: 12/08/2022] [Indexed: 06/17/2023]
Abstract
An electroactive dynamic membrane (EADM), which enabled simultaneous solid-liquid separation and contaminants removal, has been developed by electrostimulation using domestic wastewater as inoculum. Results showed that both the control dynamic membrane (CDM), without electrical stimulation, and the EADM systems exhibited stable removal performance with chemical oxygen demand (COD), and a robustness in responding to a fluctuating organic load. With the introduction of a weak electrical field, the EADM transmembrane pressure (TMP) was significantly reduced (0.02 kPa/d) compared with the control (0.20 kPa/d). In the treatment of methyl orange (MO), the EADM system achieved a decolorization efficiency of 85.87 %, much higher than the control dynamic membrane (CDM) system (58.84 %), which can be attributed to electrical stimulation and H2 production on cathode. Microbial analysis has established that electrostimulation enriched the electroactive bacteria in the dynamic biofilm, and shaped the microbial structure, with improved contaminant removal. The results of this study highlight the potential of regulating the microbial community and creating a beneficial biofilm as a dynamic layer to facilitate contaminant removal.
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Affiliation(s)
- Yang Yang
- College of Environmental Science and Engineering, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China; MOE Key Laboratory of Pollution Processes and Environmental Criteria, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China; Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China
| | - Jinning Wang
- College of Environmental Science and Engineering, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China; MOE Key Laboratory of Pollution Processes and Environmental Criteria, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China; Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China
| | - Mei Chen
- College of Environmental Science and Engineering, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China; MOE Key Laboratory of Pollution Processes and Environmental Criteria, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China; Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China.
| | - Nan Li
- School of Environmental Science and Engineering, Tianjin University, No. 35 Yaguan Road, Jinnan District, Tianjin 300350, China
| | - Jiaguo Yan
- Division of Oilfield Chemicals, China Oilfield Services Limited, No. 1581, Haichuan Road, Binhai New District, Tianjin, China
| | - Xin Wang
- College of Environmental Science and Engineering, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China; MOE Key Laboratory of Pollution Processes and Environmental Criteria, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China; Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China
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Minimizing the Lag Phase of Cupriavidus necator Growth under Autotrophic, Heterotrophic, and Mixotrophic Conditions. Appl Environ Microbiol 2023; 89:e0200722. [PMID: 36719244 PMCID: PMC9972949 DOI: 10.1128/aem.02007-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Cupriavidus necator has the unique metabolic capability to grow under heterotrophic, autotrophic, and mixotrophic conditions. In the current work, we examined the effect of growth conditions on the metabolic responses of C. necator. In our lab-scale experiments, autotrophic growth was rapid, with a short lag phase as the exponential growth stage was initiated in 6 to 12 h. The lag phase extended significantly (>22 h) at elevated O2 and CO2 partial pressures, while the duration of the lag phase was independent of the H2 or N2 partial pressure. Under heterotrophic conditions with acetate as the organic substrate, the lag phase length was short (<12 h), but it increased with increasing acetate concentrations. When glucose and glycerol were provided as the organic substrate, the lag phase was consistently long (>12 h) regardless of the examined substrate concentrations (up to 10.0 g/L). In the transition experiments, C. necator cells showed rapid transitions from autotrophic to heterotrophic growth in less than 12 h and vice versa. Our experimental results indicate that C. necator can rapidly grow with both autotrophic and heterotrophic substrates, while the lag time substantially increases with nonacetate organic substrates (e.g., glucose or glycerol), high acetate concentrations, and high O2 and CO2 partial pressures. IMPORTANCE The current work investigated the inhibition of organic and gaseous substrates on the microbial adaption of Cupriavidus necator under several metabolic conditions commonly employed for commercial polyhydroxyalkanoate production. We also proposed a two-stage cultivation system to minimize the lag time required to change over between the heterotrophic, autotrophic, and mixotrophic pathways.
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Liu Y, Zhao Q, Liao C, Tian L, Yan X, Li N, Wang X. Anaerobic bioreduction of elemental sulfur improves bioavailability of Fe (III) oxides for bioremediation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 858:159794. [PMID: 36374751 DOI: 10.1016/j.scitotenv.2022.159794] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 10/04/2022] [Accepted: 10/24/2022] [Indexed: 06/16/2023]
Abstract
Fe(III) oxides are ubiquitous electron acceptors for anaerobic bioremediation, although their bioavailability was limited due to the passivation of secondary mineralization products. Here we found the solid S0 can be added to improve their bioavailability. Using lepidocrocite (γ-FeOOH), acetate and Geobacter sulfurreducens PCA as representatives of Fe(III) oxides, intermediate of pollutant degradation and microbes, a 6 times higher amount of FeOOH reduction in the presence of S0 was observed with a time needed for S0 reduction shortened by half. The bioreduction of S0 activated the reduction of FeOOH, while the product (conductive FeS) may have bridged electron transfer across the cell membrane and periplasm. The proportion of excessive Fe(II) produced from Fe(III) was quantified as a direct bioreduction (26 %), with an abiotic FeOOH reduction to FeS (20 %) and an FeS-conducted FeOOH bioreduction (54 %), which highlight the key role of gradually formed FeS from S0 in the bioreduction of FeOOH. Our results showed that S0 can be an effective additive for the bioremediation of environments with abundant Fe(III) oxides, which has broader implications for elemental biogeochemical cycling.
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Affiliation(s)
- Ying Liu
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China
| | - Qian Zhao
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China
| | - Chengmei Liao
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China
| | - Lili Tian
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China
| | - Xuejun Yan
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China
| | - Nan Li
- School of Environmental Science and Engineering, Tianjin University, No. 135 Yaguan Road, Jinnan District, Tianjin 300350, China
| | - Xin Wang
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China.
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Gutensohn M, Schaefer JK, Maas TJ, Skyllberg U, Björn E. Metabolic turnover of cysteine-related thiol compounds at environmentally relevant concentrations by Geobacter sulfurreducens. Front Microbiol 2023; 13:1085214. [PMID: 36713222 PMCID: PMC9874932 DOI: 10.3389/fmicb.2022.1085214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 12/22/2022] [Indexed: 01/12/2023] Open
Abstract
Low-molecular-mass (LMM) thiol compounds are known to be important for many biological processes in various organisms but LMM thiols are understudied in anaerobic bacteria. In this work, we examined the production and turnover of nanomolar concentrations of LMM thiols with a chemical structure related to cysteine by the model iron-reducing bacterium Geobacter sulfurreducens. Our results show that G. sulfurreducens tightly controls the production, excretion and intracellular concentration of thiols depending on cellular growth state and external conditions. The production and cellular export of endogenous cysteine was coupled to the extracellular supply of Fe(II), suggesting that cysteine excretion may play a role in cellular trafficking to iron proteins. Addition of excess exogenous cysteine resulted in a rapid and extensive conversion of cysteine to penicillamine by the cells. Experiments with added isotopically labeled cysteine confirmed that penicillamine was formed by a dimethylation of the C-3 atom of cysteine and not via indirect metabolic responses to cysteine exposure. This is the first report of de novo metabolic synthesis of this compound. Penicillamine formation increased with external exposure to cysteine but the compound did not accumulate intracellularly, which may suggest that it is part of G. sulfurreducens' metabolic strategy to maintain cysteine homeostasis. Our findings highlight and expand on processes mediating homeostasis of cysteine-like LMM thiols in strict anaerobic bacteria. The formation of penicillamine is particularly noteworthy and this compound warrants more attention in microbial metabolism studies.
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Affiliation(s)
| | - Jeffra K. Schaefer
- Department of Environmental Sciences, Rutgers University, New Brunswick, NJ, United States
| | - Torben J. Maas
- Institute of Inorganic and Analytical Chemistry, University of Münster, Corrensstraße, Münster, Germany
| | - Ulf Skyllberg
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden
| | - Erik Björn
- Department of Chemistry, Umeå University, Umeå, Sweden,*Correspondence: Erik Björn, ✉
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Howley E, Ki D, Krajmalnik-Brown R, Torres CI. Geobacter sulfurreducens' Unique Metabolism Results in Cells with a High Iron and Lipid Content. Microbiol Spectr 2022; 10:e0259322. [PMID: 36301091 PMCID: PMC9769739 DOI: 10.1128/spectrum.02593-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 09/24/2022] [Indexed: 01/07/2023] Open
Abstract
Geobacter sulfurreducens is a ubiquitous iron-reducing bacterium in soils, and in engineered systems, it can respire an electrode to produce measurable electric current. Its unique metabolism, heavily dependent on an extensive network of cytochromes, requires a unique cell composition. In this work, we used metallomics, cell fraction and elemental analyses, and transcriptomics to study and analyze the cell composition of G. sulfurreducens. Elemental composition studies (C, H, O, N, and ash content) showed high C:O and H:O ratios of approximately 1.7:1 and 0.25:1, indicative of more reduced cell composition that is consistent with high lipid content. Our study shows that G. sulfurreducens cells have a large amount of iron (2 ± 0.2 μg/g dry weight) and lipids (32 ± 0.5% dry weight/dry weight) and that this composition does not change whether the cells are grown with a soluble or an insoluble electron acceptor. The high iron concentration, higher than similar microorganisms, is attributed to the production of cytochromes that are abundant in transcriptomic analyses in both solid and soluble electron acceptor growth. The unique cell composition of G. sulfurreducens must be considered when growing this microorganism for lab studies and commercial applications. IMPORTANCE Geobacter sulfurreducens is an electroactive microorganism. In nature, it grows on metallic minerals by transferring electrons to them, effectively "breathing" metals. In a manmade system, it respires an electrode to produce an electric current. It has become a model organism for the study of electroactive organisms. There are potential biotechnological applications of an organism that can bridge the gap between biology and electrical signal and, as a ubiquitous iron reducer in soils around the world, G. sulfurreducens has an impact on the global iron cycle. We measured the concentrations of metals, macromolecules, and basic elements in G. sulfurreducens to define this organism's composition. We also used gene expression data to discuss which proteins those metals could be associated with. We found that G. sulfurreducens has a large amount of lipid and iron compared to other bacteria-these observations are important for future microbiologists and biotechnologists working with the organism.
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Affiliation(s)
- Ethan Howley
- Biodesign Swette Center for Environmental Biotechnology, Arizona State University, Tempe, Arizona, USA
- School for Sustainable Engineering and the Built Environment, Arizona State University, Tempe, Arizona, USA
| | - Dongwon Ki
- Biodesign Swette Center for Environmental Biotechnology, Arizona State University, Tempe, Arizona, USA
- Division of Living and the Built Environment Research, Seoul Institute of Technology, Seoul, South Korea
| | - Rosa Krajmalnik-Brown
- Biodesign Swette Center for Environmental Biotechnology, Arizona State University, Tempe, Arizona, USA
- School for Sustainable Engineering and the Built Environment, Arizona State University, Tempe, Arizona, USA
| | - César I. Torres
- Biodesign Swette Center for Environmental Biotechnology, Arizona State University, Tempe, Arizona, USA
- School for Engineering of Matter Transport and Energy, Arizona State University, Tempe, Arizona, USA
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Rai A, Saha SP, Manvar T, Bhattacharjee A. A shotgun approach to explore the bacterial diversity and a brief insight into the glycoside hydrolases of Samiti lake located in the Eastern Himalayas. J Genet Eng Biotechnol 2022; 20:162. [PMID: 36469176 PMCID: PMC9723087 DOI: 10.1186/s43141-022-00444-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Accepted: 11/12/2022] [Indexed: 12/12/2022]
Abstract
BACKGROUND The Himalayas have always been an enigma and, being biodiversity hotspots, are considered extremely important from an ecological point of view. Recent advances in studies regarding high-altitude lakes have garnered relevant importance as these habitats could harbor potential psychrophilic and psychrotrophic microbes with bio-prospective applications. Contemplating the above scenario, the present study has been undertaken to understand the diversity and the functional capacities of the microbes thriving in this lake. RESULTS In our present study on Samiti Lake, the abundance of Proteobacteria as the major phylum was seen in both the soil and water samples. Incase of the ABSLW (water) and ABS1 (soil) sample, 148,066 and 239,754 predicted genes, were taken for functional analysis. The KEGG analysis showed that ABSLW and ABS1 had 122,911 and 160,268, genes assigned to KO terms respectively. Whereas in case of COG functional analysis, 104,334 and 130,191 genes were assigned to different COG classes for ABSLW and ABS1 respectively. Further, on studying the glycoside hydrolases, an abundance of GH13, GH2, GH3, GH43, and GH23 in both the soil and water samples were seen. CONCLUSION Our study has provided a comprehensive report about the bacterial diversity and functional capacities of microbes thriving in Samiti Lake. It has also thrown some light on the occurrence of glycoside hydrolases in this region, as they have numerous biotechnological applications in different sectors.
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Affiliation(s)
- Aditi Rai
- grid.412222.50000 0001 1188 5260Department of Microbiology, University of North Bengal, P.O. NBU, District Darjeeling, West Bengal, Pin-734013 India
| | - Shyama Prasad Saha
- grid.412222.50000 0001 1188 5260Department of Microbiology, University of North Bengal, P.O. NBU, District Darjeeling, West Bengal, Pin-734013 India
| | - Toral Manvar
- Xcelris Labs Ltd, Ahmedabad, Gujarat 380006 India
| | - Arindam Bhattacharjee
- grid.412222.50000 0001 1188 5260Department of Microbiology, University of North Bengal, P.O. NBU, District Darjeeling, West Bengal, Pin-734013 India
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Wang G, Jiang Y, Tang K, Zhang Y, Andersen HR. Efficient recovery of dissolved Fe(II) from near neutral pH Fenton via microbial electrolysis. JOURNAL OF HAZARDOUS MATERIALS 2022; 436:129196. [PMID: 35739726 DOI: 10.1016/j.jhazmat.2022.129196] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 05/17/2022] [Accepted: 05/18/2022] [Indexed: 06/15/2023]
Abstract
Fe(II) regeneration from ferric sludge via a biocathode and citrate system has recently been proposed to avoid iron-sludge accumulation and iron consumption in homogeneous Fenton treatments. However, poor regeneration rate of Fe(II) from ferric sludge at a near-neutral pH, without an iron-complexing agent, limited its wider practical application. Here, a biocathode augmented with Geobacter sulfurreducens hosted by a microbial electrolysis cell was developed to efficiently regenerate dissolved Fe(II) from ferric sludge at near-neutral pH levels, without using iron-complexing agents. In the Geobacter sulfurreducens-rich biocathode without complexing agents, the regeneration rate of dissolved Fe(II) increased three-fold compared with the biocathode before inoculating Geobacter sulfurreducens. The highest concentration of dissolved Fe(II) increased from 45 mg Fe/L to 199 mg Fe/L at pH 6 when 0.5 V of voltage was applied. Furthermore, 84 mg Fe/L of dissolved Fe(II) was successfully regenerated from ferric sludge during the 123 days' operation of flow-through biocathode. Finally, the regenerated Fe(II) solution without organic matters was successfully applied in a near-neutral pH Fenton treatment to remove recalcitrant pollutants. This Geobacter sulfurreducens-rich biocathode, with its low chemical consumption, high regeneration rate and feasibility for continuous flow operation, offers a more efficient method to realize iron-free in homogeneous Fenton treatments.
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Affiliation(s)
- Guan Wang
- Department of Environmental Engineering, Technical University of Denmark, DK-2800 Lyngby, Denmark
| | - Yufeng Jiang
- Department of Environmental Engineering, Technical University of Denmark, DK-2800 Lyngby, Denmark
| | - Kai Tang
- Department of Environmental Engineering, Technical University of Denmark, DK-2800 Lyngby, Denmark
| | - Yifeng Zhang
- Department of Environmental Engineering, Technical University of Denmark, DK-2800 Lyngby, Denmark.
| | - Henrik Rasmus Andersen
- Department of Environmental Engineering, Technical University of Denmark, DK-2800 Lyngby, Denmark
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A new angle to control concentration profiles at electroactive biofilm interfaces: investigating a microfluidic perpendicular flow approach. Electrochim Acta 2022. [DOI: 10.1016/j.electacta.2022.141071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Shi XC, Tremblay PL, Xue M, Song X, Zhang T. Fumarate disproportionation by Geobacter sulfurreducens and its involvement in biocorrosion and interspecies electron transfer. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 827:154251. [PMID: 35245554 DOI: 10.1016/j.scitotenv.2022.154251] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 02/14/2022] [Accepted: 02/26/2022] [Indexed: 06/14/2023]
Abstract
The model electroactive bacterium Geobacter sulfurreducens can acquire electrons directly from solid donors including metals and other species. Reports on this physiology concluding that solid donors are the only electron sources were conducted with fumarate believed to serve exclusively as the terminal electron acceptor (TEA). Here, G. sulfurreducens was repeatedly transferred for adaptation within a growth medium containing only fumarate and no other solid or soluble substrate. The resulting evolved strain grew efficiently with either the C4-dicarboxylate fumarate or malate acting simultaneously as electron donor, carbon source, and electron acceptor via disproportionation. Whole-genome sequencing identified 38 mutations including one in the regulator PilR known to repress the expression of the C4-dicarboxylate antiporter DcuB essential to G. sulfurreducens when growing with fumarate. Futhermore, the PilR mutation was identical to the sole mutation previously reported in an evolved G. sulfurreducens grown in a co-culture assumed to derive energy solely from direct interspecies electron transfer, but cultivated with fumarate as the TEA. When cultivating the fumarate-adapted strain in the presence of stainless steel and fumarate, biocorrosion was observed and bacterial growth was accelerated 2.3 times. These results suggest that G. sulfurreducens can conserve energy concomitantly from C4-dicarboxylate disproportionation and the oxidation of a solid electron donor. This co-metabolic capacity confers an advantage to Geobacter for survival and colonization and explains in part why these microbes are omnipresent in different anaerobic ecosystems.
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Affiliation(s)
- Xiao-Chen Shi
- School of Chemistry, Chemical Engineering, and Life Science, Wuhan University of Technology, Wuhan 430070, PR China; School of Resources and Environmental Engineering, Wuhan University of Technology, Wuhan 430070, PR China; Wuhan University of Technology Advanced Engineering Technology Research Institute of Zhongshan City, Zhongshan 528437, PR China
| | - Pier-Luc Tremblay
- School of Chemistry, Chemical Engineering, and Life Science, Wuhan University of Technology, Wuhan 430070, PR China; State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070, PR China; Sanya Science and Education Innovation Park, Wuhan University of Technology, Sanya 572024, PR China
| | - Miao Xue
- Institut WUT-AMU, Wuhan University of Technology, Wuhan 430070, PR China
| | - Xinyi Song
- Institut WUT-AMU, Wuhan University of Technology, Wuhan 430070, PR China
| | - Tian Zhang
- School of Chemistry, Chemical Engineering, and Life Science, Wuhan University of Technology, Wuhan 430070, PR China; School of Resources and Environmental Engineering, Wuhan University of Technology, Wuhan 430070, PR China; Institut WUT-AMU, Wuhan University of Technology, Wuhan 430070, PR China; State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070, PR China; Sanya Science and Education Innovation Park, Wuhan University of Technology, Sanya 572024, PR China.
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Karamash M, Stumpe M, Dengjel J, Salgueiro CA, Giese B, Fromm KM. Reduction Kinetic of Water Soluble Metal Salts by Geobacter sulfurreducens: Fe2+/Hemes Stabilize and Regulate Electron Flux Rates. Front Microbiol 2022; 13:909109. [PMID: 35783399 PMCID: PMC9248073 DOI: 10.3389/fmicb.2022.909109] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 05/20/2022] [Indexed: 01/17/2023] Open
Abstract
Geobacter sulfurreducens is a widely applied microorganism for the reduction of toxic metal salts, as an electron source for bioelectrochemical devices, and as a reagent for the synthesis of nanoparticles. In order to understand the influence of metal salts, and of electron transporting, multiheme c-cytochromes on the electron flux during respiration of G. sulfurreducens, the reduction kinetic of Fe3+, Co3+, V5+, Cr6+, and Mn7+ containing complexes were measured. Starting from the resting phase, each G. sulfurreducens cell produced an electron flux of 3.7 × 105 electrons per second during the respiration process. Reduction rates were within ± 30% the same for the 6 different metal salts, and reaction kinetics were of zero order. Decrease of c-cytochrome concentrations by downregulation and mutation demonstrated that c-cytochromes stabilized respiration rates by variation of their redox states. Increasing Fe2+/heme levels increased electron flux rates, and induced respiration flexibility. The kinetic effects parallel electrochemical results of G. sulfurreducens biofilms on electrodes, and might help to optimize bioelectrochemical devices.
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Affiliation(s)
- Maksym Karamash
- Department of Chemistry, University of Fribourg, Fribourg, Switzerland
| | - Michael Stumpe
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Jörn Dengjel
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Carlos A. Salgueiro
- Associate Laboratory i4HB – Institute for Health and Bioeconomy, School of Science and Technology, NOVA University Lisbon, Costa da Caparica, Portugal
- UCIBIO – Applied Molecular Biosciences Unit, Chemistry Department, School of Science and Technology, NOVA University Lisbon, Costa da Caparica, Portugal
| | - Bernd Giese
- Department of Chemistry, University of Fribourg, Fribourg, Switzerland
- *Correspondence: Bernd Giese,
| | - Katharina M. Fromm
- Department of Chemistry, University of Fribourg, Fribourg, Switzerland
- Katharina M. Fromm,
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Yoshimi T, Fujii S, Oki H, Igawa T, Adams HR, Ueda K, Kawahara K, Ohkubo T, Hough MA, Sambongi Y. Crystal structure of thermally stable homodimeric cytochrome c′-β from Thermus thermophilus. Acta Crystallogr F Struct Biol Commun 2022; 78:217-225. [DOI: 10.1107/s2053230x22005088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 05/11/2022] [Indexed: 11/10/2022] Open
Abstract
Cytochrome c′-β is a heme protein that belongs to the cytochrome P460 family and consists of homodimeric subunits with a predominantly antiparallel β-sheet fold. Here, the crystal structure of cytochrome c′-β from the thermophilic Thermus thermophilus (TTCP-β) is reported at 1.74 Å resolution. TTCP-β has a typical antiparallel β-sheet fold similar to that of cytochrome c′-β from the moderately thermophilic Methylococcus capsulatus (MCCP-β). The phenylalanine cap structure around the distal side of the heme is also similar in TTCP-β and MCCP-β, indicating that both proteins similarly bind nitric oxide and carbon monoxide, as observed spectroscopically. Notably, TTCP-β exhibits a denaturation temperature of 117°C, which is higher than that of MCCP-β. Mutational analysis reveals that the increased homodimeric interface area of TTCP-β contributes to its high thermal stability. Furthermore, 14 proline residues, which are mostly located in the TTCP-β loop regions, possibly contribute to the rigid loop structure compared with MCCP-β, which has only six proline residues. These findings, together with those from phylogenetic analysis, suggest that the structures of Thermus cytochromes c′-β, including TTCP-β, are optimized for function under the high-temperature conditions in which the source organisms live.
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Tian L, Yan X, Wang D, Du Q, Wan Y, Zhou L, Li T, Liao C, Li N, Wang X. Two key Geobacter species of wastewater-enriched electroactive biofilm respond differently to electric field. WATER RESEARCH 2022; 213:118185. [PMID: 35183018 DOI: 10.1016/j.watres.2022.118185] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 02/10/2022] [Accepted: 02/11/2022] [Indexed: 06/14/2023]
Abstract
Electroactive biofilms have attracted increasing attention due to their unique ability to exchange electrons with electrodes. Geobacter spp. are widely found to be dominant in biofilms in acetate-rich environments when an appropriate voltage is applied, but it is still largely unknown how these bacteria are selectively enriched. Herein, two key Geobacter spp. that have been demonstrated predominant in wastewater-enriched electroactive biofilm after long-term operation, G. sulfurreducens and G. anodireducens, responded to electric field (EF) differently, leading to a higher abundance of EF-sensitive G. anodireducens in the strong EF region after cocultivation with G. sulfurreducens. Transcriptome analysis indicated that two-component systems containing sensor histidine kinases and response regulators were the key for EF sensing in G. anodireducens rather than in G. sulfurreducens, which are closely connected to chemotaxis, c-di-GMP, fatty acid metabolism, pilus, oxidative phosphorylation and transcription, resulting in an increase in extracellular polymeric substance secretion and rapid cell proliferation. Our data reveal the mechanism by which EF select specific Geobacter spp. over time, providing new insights into Geobacter biofilm formation regulated by electricity.
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Affiliation(s)
- Lili Tian
- MOE Key Laboratory of Pollution Processes and Environmental Criteria / Tianjin Key Laboratory of Environmental Remediation and Pollution Control / College of Environmental Science and Engineering, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China
| | - Xuejun Yan
- MOE Key Laboratory of Pollution Processes and Environmental Criteria / Tianjin Key Laboratory of Environmental Remediation and Pollution Control / College of Environmental Science and Engineering, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China
| | - Dongbin Wang
- School of Public Health, Guangdong Medical University, Xincheng Road, Dongguan 523000, China
| | - Qing Du
- School of Environmental and Municipal Engineering, Tianjin Chengjian University, Tianjin 300384, China
| | - Yuxuan Wan
- MOE Key Laboratory of Pollution Processes and Environmental Criteria / Tianjin Key Laboratory of Environmental Remediation and Pollution Control / College of Environmental Science and Engineering, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China
| | - Lean Zhou
- School of Hydraulic Engineering, Changsha University of Science and Technology, Changsha 410114, China
| | - Tian Li
- MOE Key Laboratory of Pollution Processes and Environmental Criteria / Tianjin Key Laboratory of Environmental Remediation and Pollution Control / College of Environmental Science and Engineering, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China
| | - Chengmei Liao
- MOE Key Laboratory of Pollution Processes and Environmental Criteria / Tianjin Key Laboratory of Environmental Remediation and Pollution Control / College of Environmental Science and Engineering, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China
| | - Nan Li
- School of Environmental Science and Engineering, Tianjin University, No. 35 Yaguan Road, Jinnan District, Tianjin 300350, China
| | - Xin Wang
- MOE Key Laboratory of Pollution Processes and Environmental Criteria / Tianjin Key Laboratory of Environmental Remediation and Pollution Control / College of Environmental Science and Engineering, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China.
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Scarabotti F, Bühler K, Schmidt M, Harnisch F. Thickness and roughness of transparent gold-palladium anodes have no impact on growth kinetics and yield coefficients of early-stage Geobacter sulfurreducens biofilms. Bioelectrochemistry 2022; 144:108043. [PMID: 34959027 DOI: 10.1016/j.bioelechem.2021.108043] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 11/24/2021] [Accepted: 12/13/2021] [Indexed: 01/05/2023]
Abstract
Geobacter sulfurreducens is the model organism for electroactive microorganisms performing direct extracellular electron transfer and forming thick mature biofilm electrodes. Although numerous physiological properties of mature biofilm electrodes are deciphered, there is an extensive gap of knowledge on the early-stage biofilm formation. We have shown recently that transparent gold-palladium (AuPd) electrodes allow for analysis of early-stage biofilm formation using confocal laser scanning microscopy. Here we analysed the influence of thickness (ranging from 12.5 to 200 nm) and roughness of AuPd electrodes on physiological parameters of G. sulfurreducens early-stage biofilms. We show that when grown potentiostatically at -200 mV vs. Ag/ AgCl sat. KCl neither maximum current density (jmax of ∼ 80-150 µA cm-2) nor lag time (lag t of ∼ 0.2-0.4 days) or single cell yield coefficients (YNe of 1.43 × 1012 cells mole--1) of the biofilms are influenced by the electrode preparation. This confirms the robustness of the experimental approach, which is an inevitable prerequisite for obtaining reliable results in follow-up experiments.
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Affiliation(s)
- Francesco Scarabotti
- Department of Environmental Microbiology, Helmholtz-Centre for Environmental Research - UFZ, Leipzig, Germany
| | - Katja Bühler
- Department Solar Materials, Helmholtz-Centre for Environmental Research - UFZ, Leipzig, Germany
| | - Matthias Schmidt
- Department of Isotope Biogeochemistry, Helmholtz-Centre for Environmental Research - UFZ, Leipzig, Germany
| | - Falk Harnisch
- Department of Environmental Microbiology, Helmholtz-Centre for Environmental Research - UFZ, Leipzig, Germany.
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46
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Dong H, Cheng J, Li H, Yue L, Xia R, Zhou J. Electron transfer from Geobacter sulfurreducens to mixed methanogens improved methane production with feedstock gases of H 2 and CO 2. BIORESOURCE TECHNOLOGY 2022; 347:126680. [PMID: 34999194 DOI: 10.1016/j.biortech.2022.126680] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 12/29/2021] [Accepted: 01/01/2022] [Indexed: 06/14/2023]
Abstract
In order to solve problems of poor utilization of H2 and CO2 in biomethane conversion with mixed methanogens due to multi-channel competition and nondirectional electron transfer, Geobacter sulfurreducens were cocultured with mixed methanogens to promote oriented metabolic pathway of H2 and CO2 to produce CH4. When inoculation volume ratio of G. sulfurreducens to mixed methanogens was 2:4, CH4 yield increased to 0.24 mL/ml H2 (close to the maximum theoretical yield of 0.25 mL/ml H2) and conversion efficiency of H2 to CH4 increased from 72 to 96%. Electrochemical detection and three-dimensional fluorescence spectra showed that the co-culture system had an increased metabolic capacity and spectral intensity of fulvic acid-like compounds was enhanced, which mediated direct interspecific electron transfer to produce CH4. The 16S rRNA gene sequencing showed that relative abundance of G. sulfurreducens and Methanoculleus increased, indicating an established syntrophic relationship between G. sulfurreducens and Methanoculleus.
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Affiliation(s)
- Haiquan Dong
- State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China
| | - Jun Cheng
- State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China.
| | - Hui Li
- State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China
| | - Liangchen Yue
- State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China
| | - Rongxin Xia
- State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China
| | - Junhu Zhou
- State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China
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Jessen GL, Chen LX, Mori JF, Nelson TEC, Slater GF, Lindsay MBJ, Banfield JF, Warren LA. Alum Addition Triggers Hypoxia in an Engineered Pit Lake. Microorganisms 2022; 10:microorganisms10030510. [PMID: 35336086 PMCID: PMC8953953 DOI: 10.3390/microorganisms10030510] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 02/09/2022] [Accepted: 02/11/2022] [Indexed: 01/04/2023] Open
Abstract
Here, we examine the geobiological response to a whole-lake alum (aluminum sulfate) treatment (2016) of Base Mine Lake (BML), the first pilot-scale pit lake established in the Alberta oil sands region. The rationale for trialing this management amendment was based on its successful use to reduce internal phosphorus loading to eutrophying lakes. Modest increases in water cap epilimnetic oxygen concentrations, associated with increased Secchi depths and chlorophyll-a concentrations, were co-incident with anoxic waters immediately above the fluid fine tailings (FFT) layer post alum. Decreased water cap nitrate and detectable sulfide concentrations, as well as increased hypolimnetic phospholipid fatty acid abundances, signaled greater anaerobic heterotrophic activity. Shifts in microbial community to groups associated with greater organic carbon degradation (i.e., SAR11-LD12 subclade) and the SRB group Desulfuromonodales emerged post alum and the loss of specialist groups associated with carbon-limited, ammonia-rich restricted niches (i.e., MBAE14) also occurred. Alum treatment resulted in additional oxygen consumption associated with increased autochthonous carbon production, watercap anoxia and sulfide generation, which further exacerbate oxygen consumption associated with on-going FFT mobilized reductants. The results illustrate the importance of understanding the broader biogeochemical implications of adaptive management interventions to avoid unanticipated outcomes that pose greater risks and improve tailings reclamation for oil sands operations and, more broadly, the global mining sector.
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Affiliation(s)
- Gerdhard L. Jessen
- Instituto de Ciencias Marinas y Limnológicas, Universidad Austral de Chile, Valdivia 5090000, Chile
- Department of Civil and Mineral Engineering, University of Toronto, Toronto, ON M5S 1A4, Canada; (J.F.M.); (T.E.C.N.)
- Correspondence: (G.L.J.); (L.A.W.)
| | - Lin-Xing Chen
- Department of Earth and Planetary Science, University of California, Berkeley, CA 94706, USA; (L.-X.C.); (J.F.B.)
| | - Jiro F. Mori
- Department of Civil and Mineral Engineering, University of Toronto, Toronto, ON M5S 1A4, Canada; (J.F.M.); (T.E.C.N.)
- Graduate School of Nanobioscience, Yokohama City University, Yokohama 236-0027, Japan
| | - Tara E. Colenbrander Nelson
- Department of Civil and Mineral Engineering, University of Toronto, Toronto, ON M5S 1A4, Canada; (J.F.M.); (T.E.C.N.)
- School of Earth, Environment and Society, McMaster University, Hamilton, ON L8S 4L8, Canada;
| | - Gregory F. Slater
- School of Earth, Environment and Society, McMaster University, Hamilton, ON L8S 4L8, Canada;
| | - Matthew B. J. Lindsay
- Department of Geological Sciences, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada;
| | - Jillian F. Banfield
- Department of Earth and Planetary Science, University of California, Berkeley, CA 94706, USA; (L.-X.C.); (J.F.B.)
| | - Lesley A. Warren
- Department of Civil and Mineral Engineering, University of Toronto, Toronto, ON M5S 1A4, Canada; (J.F.M.); (T.E.C.N.)
- School of Earth, Environment and Society, McMaster University, Hamilton, ON L8S 4L8, Canada;
- Correspondence: (G.L.J.); (L.A.W.)
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Shrestha R, Cerna K, Spanek R, Bartak D, Cernousek T, Sevcu A. The effect of low-pH concrete on microbial community development in bentonite suspensions as a model for microbial activity prediction in future nuclear waste repository. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 808:151861. [PMID: 34838551 DOI: 10.1016/j.scitotenv.2021.151861] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 11/10/2021] [Accepted: 11/17/2021] [Indexed: 06/13/2023]
Abstract
Concrete as an important component of an engineered barrier system in deep geological repositories (DGR) for radioactive waste may come into contact with bentonite, or other clays, rich in indigenous microorganisms, with potentially harmful impacts on barrier integrity. Our study aimed to assess the effect of a concrete environment on indigenous bentonite and groundwater microbial communities as these particular conditions will select for the potentially harmful microorganisms to the concrete in the future DGR. The two-month experiment under anoxic conditions consisted of crushed, aged, low-pH concrete, Czech Ca-Mg bentonite, and anoxic groundwater, with control samples without concrete or with sterile groundwater. The microbial diversity and proliferation were estimated by qPCR and 16S rRNA gene amplicon sequencing. The presence of concrete had a strong effect on microbial diversity and reduced the increase in total microbial biomass, though low-pH concrete harbored indigenous bacteria. The growth of sulfate reducers was also limited in concrete samples. Several genera, such as Massilia, Citrifermentans, and Lacunisphaera, dominant in bentonite controls, were suppressed in concrete-containing samples. In contrast, genera such as Bacillus, Dethiobacter and Anaerosolibacter specifically proliferated in the presence of concrete. Genera such as Thermincola or Pseudomonas exhibited high versatility and proliferated well under both conditions. Because several of the detected bacterial genera are known to affect concrete integrity, further long-term studies are needed to estimate the effect of bentonite and groundwater microorganisms on concrete stability in future DGR.
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Affiliation(s)
- Rojina Shrestha
- Technical University of Liberec, Institute for Nanomaterials, Advanced Technologies and Innovations, Bendlova 1407/7, 461 17 Liberec 1, Czech Republic
| | - Katerina Cerna
- Technical University of Liberec, Institute for Nanomaterials, Advanced Technologies and Innovations, Bendlova 1407/7, 461 17 Liberec 1, Czech Republic.
| | - Roman Spanek
- Technical University of Liberec, Institute for Nanomaterials, Advanced Technologies and Innovations, Bendlova 1407/7, 461 17 Liberec 1, Czech Republic
| | - Deepa Bartak
- Technical University of Liberec, Institute for Nanomaterials, Advanced Technologies and Innovations, Bendlova 1407/7, 461 17 Liberec 1, Czech Republic
| | - Tomas Cernousek
- Research Centre Rez, Department of Nuclear Fuel Cycle, Husinec-Rez 130, 25068, Czech Republic
| | - Alena Sevcu
- Technical University of Liberec, Institute for Nanomaterials, Advanced Technologies and Innovations, Bendlova 1407/7, 461 17 Liberec 1, Czech Republic
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Kuchenbuch A, Frank R, Ramos JV, Jahnke HG, Harnisch F. Electrochemical Microwell Plate to Study Electroactive Microorganisms in Parallel and Real-Time. Front Bioeng Biotechnol 2022; 9:821734. [PMID: 35242754 PMCID: PMC8887713 DOI: 10.3389/fbioe.2021.821734] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 12/28/2021] [Indexed: 11/26/2022] Open
Abstract
Microbial resource mining of electroactive microorganism (EAM) is currently methodically hampered due to unavailable electrochemical screening tools. Here, we introduce an electrochemical microwell plate (ec-MP) composed of a 96 electrochemical deepwell plate and a recently developed 96-channel multipotentiostat. Using the ec-MP we investigated the electrochemical and metabolic properties of the EAM models Shewanella oneidensis and Geobacter sulfurreducens with acetate and lactate as electron donor combined with an individual genetic analysis of each well. Electrochemical cultivation of pure cultures achieved maximum current densities (j max) and coulombic efficiencies (CE) that were well in line with literature data. The co-cultivation of S. oneidensis and G. sulfurreducens led to an increased current density of j max of 88.57 ± 14.04 µA cm-2 (lactate) and j max of 99.36 ± 19.12 µA cm-2 (lactate and acetate). Further, a decreased time period of reaching j max and biphasic current production was revealed and the microbial electrochemical performance could be linked to the shift in the relative abundance.
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Affiliation(s)
- Anne Kuchenbuch
- Department of Environmental Microbiology, UFZ—Helmholtz-Centre for Environmental Research GmbH, Leipzig, Germany
| | - Ronny Frank
- Centre for Biotechnology and Biomedicine, Molecular Biological-Biochemical Processing Technology, Leipzig University, Leipzig, Germany
| | - José Vazquez Ramos
- Centre for Biotechnology and Biomedicine, Molecular Biological-Biochemical Processing Technology, Leipzig University, Leipzig, Germany
| | - Heinz-Georg Jahnke
- Centre for Biotechnology and Biomedicine, Molecular Biological-Biochemical Processing Technology, Leipzig University, Leipzig, Germany
| | - Falk Harnisch
- Department of Environmental Microbiology, UFZ—Helmholtz-Centre for Environmental Research GmbH, Leipzig, Germany
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50
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Amer A, Kim Y. Isolation of Pb(II)-reducing bacteria and demonstration of biological Pb(II) reduction to metallic Pb. JOURNAL OF HAZARDOUS MATERIALS 2022; 423:126975. [PMID: 34788938 DOI: 10.1016/j.jhazmat.2021.126975] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 08/13/2021] [Accepted: 08/18/2021] [Indexed: 06/13/2023]
Abstract
Pb(II) contamination imposes serious threats to human health and the environment. Biological reduction of Pb(II) to metallic Pb is an attractive method for the remediation of Pb(II)-contaminated water and sediments. In this study, Pb(II)-reducing microorganisms were isolated by the dilution-to-extinction (DTE) and streak-plate methods. As a result, Delftia acidovorans, Azonexus caeni, and Comamonas testosteroni were successfully isolated. At a high lead concentration (10 mg-Pb(II)/L), each of the isolated D. acidovorans strain Pb11 and A. caeni strain Pb2 cultures showed successful utilization of Pb(II), resulting in a 5.15- and 8.14-fold growth in 3 days, respectively. Pb(II) reduction to metallic Pb by D. acidovorans strain Pb11 and A. caeni strain Pb2 was confirmed using scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDS) was coupled with X-ray photoelectron spectroscopy (XPS). This strategic analysis was necessary to confirm the formation of metallic Pb separately from lead phosphate precipitates which are inevitable in the biological Pb(II) removal experiments. Among the 3 isolated microbes, C. testosteroni strain Pb3 did not leave immobile and detectable Pb solids in SEM-EDS analyses. D. acidovorans and A. caeni are recommended for engineered remediation of Pb(II)-contaminated wastewater and sediments.
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Affiliation(s)
- Abdelrahman Amer
- Department of Civil Engineering, McMaster University, Canada; Civil Engineering Department, Menoufia University, Egypt
| | - Younggy Kim
- Department of Civil Engineering, McMaster University, Canada.
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