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Twible LE, Whaley-Martin K, Chen LX, Colenbrander Nelson T, Arrey JL, Jarolimek CV, King JJ, Ramilo L, Sonnenberg H, Banfield JF, Apte SC, Warren LA. pH and thiosulfate dependent microbial sulfur oxidation strategies across diverse environments. Front Microbiol 2024; 15:1426584. [PMID: 39101034 PMCID: PMC11294248 DOI: 10.3389/fmicb.2024.1426584] [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: 05/01/2024] [Accepted: 06/18/2024] [Indexed: 08/06/2024] Open
Abstract
Sulfur oxidizing bacteria (SOB) play a key role in sulfur cycling in mine tailings impoundment (TI) waters, where sulfur concentrations are typically high. However, our understanding of SOB sulfur cycling via potential S oxidation pathways (sox, rdsr, and S4I) in these globally ubiquitous contexts, remains limited. Here, we identified TI water column SOB community composition, metagenomics derived metabolic repertoires, physicochemistry, and aqueous sulfur concentration and speciation in four Canadian base metal mine, circumneutral-alkaline TIs over four years (2016 - 2019). Identification and examination of genomes from nine SOB genera occurring in these TI waters revealed two pH partitioned, metabolically distinct groups, which differentially influenced acid generation and sulfur speciation. Complete sox (csox) dominant SOB (e.g., Halothiobacillus spp., Thiomonas spp.) drove acidity generation and S2O3 2- consumption via the csox pathway at lower pH (pH ~5 to ~6.5). At circumneutral pH conditions (pH ~6.5 to ~8.5), the presence of non-csox dominant SOB (hosting the incomplete sox, rdsr, and/or other S oxidation reactions; e.g. Thiobacillus spp., Sulfuriferula spp.) were associated with higher [S2O3 2-] and limited acidity generation. The S4I pathway part 1 (tsdA; S2O3 2- to S4O6 2-), was not constrained by pH, while S4I pathway part 2 (S4O6 2- disproportionation via tetH) was limited to Thiobacillus spp. and thus circumneutral pH values. Comparative analysis of low, natural (e.g., hydrothermal vents and sulfur hot springs) and high (e.g., Zn, Cu, Pb/Zn, and Ni tailings) sulfur systems literature data with these TI results, reveals a distinct TI SOB mining microbiome, characterized by elevated abundances of csox dominant SOB, likely sustained by continuous replenishment of sulfur species through tailings or mining impacted water additions. Our results indicate that under the primarily oxic conditions in these systems, S2O3 2- availability plays a key role in determining the dominant sulfur oxidation pathways and associated geochemical and physicochemical outcomes, highlighting the potential for biological management of mining impacted waters via pH and [S2O3 2-] manipulation.
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Affiliation(s)
- Lauren E. Twible
- Department of Civil and Mineral Engineering, University of Toronto, Toronto, ON, Canada
| | - Kelly Whaley-Martin
- Department of Civil and Mineral Engineering, University of Toronto, Toronto, ON, Canada
| | - Lin-Xing Chen
- Department of Earth and Planetary Science, University of California, Berkeley, Berkeley, CA, United States
| | | | - James L.S. Arrey
- Department of Civil and Mineral Engineering, University of Toronto, Toronto, ON, Canada
| | - Chad V. Jarolimek
- School of Mathematical and Physical Sciences, University of Technology Sydney, Ultimo, NSW, Australia
| | - Josh J. King
- Commonwealth Scientific Industrial and Research Organization, Black Mountain, ACT, Australia
| | | | | | - Jillian F. Banfield
- Department of Earth and Planetary Science, University of California, Berkeley, Berkeley, CA, United States
| | - Simon C. Apte
- Commonwealth Scientific Industrial and Research Organization, Clayton, VIC, Australia
| | - Lesley A. Warren
- Department of Civil and Mineral Engineering, University of Toronto, Toronto, ON, Canada
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Salem SH, Saber M, Gadow S, Kabary H, Zaghloul A. Influence of the use of remediated soil and agricultural drainage water on the safety of tomato fruits. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2024; 31:31546-31561. [PMID: 38632200 PMCID: PMC11096225 DOI: 10.1007/s11356-024-33187-z] [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: 04/22/2023] [Accepted: 03/28/2024] [Indexed: 04/19/2024]
Abstract
The objective of this study is to assess the effectiveness of different techniques employed in remediating contaminated soil and wastewater ecosystems to ensure the safety of tomato fruits (Solanum lycopersicum L. var. cerasiforme) cultivated in these environments. Three biochemical techniques T1-T3, besides two controls CCU and CCT, were used to remediate contaminated soil ecosystems using rock phosphate, elemental sulfur, bentonite, phosphate-dissolving bacteria, and Thiobacillus sp. The contaminated agricultural drainage water was remediated by a down-flow hanging sponge (DHS) system. Two experiments were conducted: a pot experiment took place in the greenhouse at the National Research Center of Cairo (Egypt) and a field experiment was carried out at the basin site in the village of El-Rahawy, applying the optimal treatment(s) identified from the greenhouse experiment. The health risk assessment for potentially toxic elements (PTEs) in the harvested tomato fruits was conducted by calculating estimated daily intake (EDI) and target risk quotient (THQ) values. Results from the greenhouse experiment indicated the high effectiveness of the DHS technique in remediating El-Rahawy agricultural drainage water. The content of PTEs after remediation was significantly reduced by 100%, 93.3%, 97.8, and 77.8% for cadmium, copper, manganese, and zinc, respectively. The application of treated drainage water in employed reclaimed soil ecosystems led to a remarkable decrease in PTE levels, especially under T3 treatment; the reduction reached 89.4%, 89.5%, and 78.4% for nickel, copper, and zinc, respectively. The bioremediation technique also reduced the content of PTEs in tomato fruits harvested from both greenhouse and field experiments; the cadmium content, for example, was below detection limits in all treatments. The T3 treatment applied in the greenhouse experiment caused the highest percentage decrease among the employed PTEs in tomato fruits grown in the greenhouse. The same trend was also reached in the field experiment. Microbiological analyses of tomato fruits revealed that E. coli, Salmonella, or S. aureus bacteria were identified on tomato fruits harvested from either greenhouses or field experiments, showing that the counted total bacteria were higher under the field experiment compared to the greenhouse experiment. The health risk assessment parameter THQ was below 1.0 for all tested metals under all treatments. This means that no potential health risk is expected from consuming tomato products produced under the different employed remediation treatments. In conclusion, the employed bioremediation techniques successfully reduced the PTE content and microbial load in both soil and drainage water ecosystems and in harvested tomato fruits. Henceforth, no health risks are expected from the consumption of this product.
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Affiliation(s)
- Salah H Salem
- Food Toxicology and Contaminants Dept., Food Industries and Nutrition Institute, National Research Centre, Cairo, 12622, Egypt.
| | - Mohamed Saber
- Agricultural Microbiology Dept., Agricultural and Biological Sciences Institute National Research Centre, Cairo, 12622, Egypt
| | - Samir Gadow
- Agricultural Microbiology Dept., Agricultural and Biological Sciences Institute National Research Centre, Cairo, 12622, Egypt
| | - Hoda Kabary
- Agricultural Microbiology Dept., Agricultural and Biological Sciences Institute National Research Centre, Cairo, 12622, Egypt
| | - Alaa Zaghloul
- Soils and Water Use Dept., Agricultural and Biological Sciences Institute National Research Centre, Cairo, 12622, Egypt
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Breuker A, Schippers A. Rates of iron(III) reduction coupled to elemental sulfur or tetrathionate oxidation by acidophilic microorganisms and detection of sulfur intermediates. Res Microbiol 2024; 175:104110. [PMID: 37544391 DOI: 10.1016/j.resmic.2023.104110] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 07/31/2023] [Accepted: 07/31/2023] [Indexed: 08/08/2023]
Abstract
Bioleaching processes and acid mine drainage (AMD) generation are mainly driven by aerobic microbial iron(II) and inorganic sulfur/compound oxidation. Dissimilatory iron(III) reduction coupled to sulfur/compound oxidation (DIRSO) by acidophilic microorganisms has been described for anaerobic cultures, but iron reduction was observed under aerobic conditions as well. Aim of this study was to explore reaction rates and mechanisms of this process. Cell-specific iron(III) reduction rates for different Acidithiobacillus (At.) strains during batch culture growth or stationary phase with iron(III) (∼40 mM) as electron acceptor and elemental sulfur or tetrathionate as electron donor (1% or 5 mM, respectively) were determined. The rates were highest under anaerobic conditions for the At. ferrooxidans type strain with 6.8 × 106 and 1.1 × 107 reduced iron(III) ions per second per cell for growth on elemental sulfur and tetrathionate, respectively. The iron(III) reduction rates were somehow lower for the anaerobically sulfur grown archaeon Ferroplasma acidiphilum, and lowest for the sulfur grown At. caldus type strain under aerobic conditions (1.7 × 106 and 7.3 × 104 reduced iron(III) ions per second per cell, respectively). The rates for five strains of At. thiooxidans (aerobe) were in between those for At. ferrooxidans (anaerobe) and At. caldus (aerobe). There was no pronounced pH dependence of iron(III) reduction rates in the range of pH 1.0-1.9 for the type strains of all species but rates increased with increasing pH for four other At. thiooxidans strains. Thiosulfate as sulfur intermediate was found for At. ferrooxidans during anaerobic growths on tetrathionate and iron(III) but not during anaerobic growths on elemental sulfur and iron(III), and a small concentration was measured during aerobic growths on tetrathionate without iron(III). For the At. thiooxidans type strain thiosulfate was found with tetrathionate grown cells under aerobic conditions in presence and absence of iron(III), but not with sulfur grown cells. Evidence for hydrogen sulfide production at low pH was found for the At. ferrooxidans as well as the At. thiooxidans type strains during microaerophilic growth on elemental sulfur and for At. ferrooxidans during anaerobic growths on tetrathionate and iron(III). The occurrence of sulfur compound intermediates supports the hypothesis that chemical reduction of iron(III) ions takes place by sulfur compounds released by the microbial cells.
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Affiliation(s)
- Anja Breuker
- Federal Institute for Geosciences and Natural Resources (BGR), Stilleweg2, 30655 Hannover, Germany
| | - Axel Schippers
- Federal Institute for Geosciences and Natural Resources (BGR), Stilleweg2, 30655 Hannover, Germany.
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4
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Zhang X, Guo T, Li H, Zhang D, Hou Y, Han Y, Song Y, Guo J. A novel sulfur autotrophic denitrification in-situ coupled sequencing batch reactor system to treat low carbon to nitrogen ratio municipal wastewater: Performance, niche equilibrium and pollutant removal mechanisms. BIORESOURCE TECHNOLOGY 2023; 387:129609. [PMID: 37597571 DOI: 10.1016/j.biortech.2023.129609] [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: 06/22/2023] [Revised: 07/30/2023] [Accepted: 08/01/2023] [Indexed: 08/21/2023]
Abstract
A novel integrated sulfur fixed-film activated sludge in SBR system (IS0FAS-SBR) was proposed to treat the low C/N ratio municipal wastewater. The effluent total inorganic nitrogen (TIN) and PO43--P decreased from 17 mg/L and 3.5 mg/L to 8.5 mg/L and 0.5 mg/L, and higher nitrogen removal efficiency was contributed by the autotrophic denitrification. Microbial response characteristics showed that catalase (CAT), reduced nicotinamide adenine dinucleotide (NADH) and extracellular polymeric substance (EPS) alleviated the oxidative stress of sulfur carrier to maintain cell activity, while metabolic activity analysis indicated that the electron transfer rate was enhanced to improve mixotrophic denitrification efficiency. Meanwhile, the increased key enzyme activities further facilitated nitrogen removal and sulfur oxidation process. Additionally, the microbial community, functional proteins and genes revealed a niche equilibrium of C, N, S metabolic bacteria. Sulfur autotrophic in-situ coupled SBR system enlarged a promising strategy for treatment of low C/N ratio municipal wastewater.
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Affiliation(s)
- Xu Zhang
- School of Environmental and Municipal Engineering, Tianjin Key Laboratory of Aquatic Science and Technology, Tianjin Chengjian University, Tianjin 300384, China; School of Civil Engineering and Architecture, Taizhou University, Taizhou 318000, Zhejiang, China
| | - Tingting Guo
- School of Civil Engineering and Architecture, Taizhou University, Taizhou 318000, Zhejiang, China
| | - Haibo Li
- School of Environmental and Municipal Engineering, Tianjin Key Laboratory of Aquatic Science and Technology, Tianjin Chengjian University, Tianjin 300384, China.
| | - Daohong Zhang
- School of Environmental and Municipal Engineering, Tianjin Key Laboratory of Aquatic Science and Technology, Tianjin Chengjian University, Tianjin 300384, China
| | - Yanan Hou
- School of Environmental and Municipal Engineering, Tianjin Key Laboratory of Aquatic Science and Technology, Tianjin Chengjian University, Tianjin 300384, China
| | - Yi Han
- School of Environmental and Municipal Engineering, Tianjin Key Laboratory of Aquatic Science and Technology, Tianjin Chengjian University, Tianjin 300384, China
| | - Yuanyuan Song
- School of Environmental and Municipal Engineering, Tianjin Key Laboratory of Aquatic Science and Technology, Tianjin Chengjian University, Tianjin 300384, China
| | - Jianbo Guo
- School of Civil Engineering and Architecture, Taizhou University, Taizhou 318000, Zhejiang, China
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5
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Páez-Pérez ED, Hernández-Sánchez A, Alfaro-Saldaña E, García-Meza JV. Disorder and amino acid composition in proteins: their potential role in the adaptation of extracellular pilins to the acidic media, where Acidithiobacillus thiooxidans grows. Extremophiles 2023; 27:31. [PMID: 37848738 DOI: 10.1007/s00792-023-01317-z] [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: 03/08/2023] [Accepted: 09/26/2023] [Indexed: 10/19/2023]
Abstract
There are few biophysical studies or structural characterizations of the type IV pilin system of extremophile bacteria, such as the acidophilic Acidithiobacillus thiooxidans. We set out to analyze their pili-comprising proteins, pilins, because these extracellular proteins are in constant interaction with protons of the acidic medium in which At. thiooxidans grows. We used the web server Operon Mapper to analyze and identify the cluster codified by the minor pilin of At. thiooxidans. In addition, we carried an in-silico characterization of such pilins using the VL-XT algorithm of PONDR® server. Our results showed that structural disorder prevails more in pilins of At. thiooxidans than in non-acidophilic bacteria. Further computational characterization showed that the pilins of At. thiooxidans are significantly enriched in hydroxy (serine and threonine) and amide (glutamine and asparagine) residues, and significantly reduced in charged residues (aspartic acid, glutamic acid, arginine and lysine). Similar results were obtained when comparing pilins from other Acidithiobacillus and other acidophilic bacteria from another genus versus neutrophilic bacteria, suggesting that these properties are intrinsic to pilins from acidic environments, most likely by maintaining solubility and stability in harsh conditions. These results give guidelines for the application of extracellular proteins of acidophiles in protein engineering.
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Affiliation(s)
- Edgar D Páez-Pérez
- Geomicrobiología, Metalurgia, Universidad Autónoma de San Luis Potosí, Sierra Leona 550, 78210, San Luis Potosí, SLP, Mexico.
| | - Araceli Hernández-Sánchez
- Geomicrobiología, Metalurgia, Universidad Autónoma de San Luis Potosí, Sierra Leona 550, 78210, San Luis Potosí, SLP, Mexico.
| | - Elvia Alfaro-Saldaña
- Geomicrobiología, Metalurgia, Universidad Autónoma de San Luis Potosí, Sierra Leona 550, 78210, San Luis Potosí, SLP, Mexico
| | - J Viridiana García-Meza
- Geomicrobiología, Metalurgia, Universidad Autónoma de San Luis Potosí, Sierra Leona 550, 78210, San Luis Potosí, SLP, Mexico
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6
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Beard S, Moya-Beltrán A, Silva-García D, Valenzuela C, Pérez-Acle T, Loyola A, Quatrini R. Pangenome-level analysis of nucleoid-associated proteins in the Acidithiobacillia class: insights into their functional roles in mobile genetic elements biology. Front Microbiol 2023; 14:1271138. [PMID: 37817747 PMCID: PMC10561277 DOI: 10.3389/fmicb.2023.1271138] [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: 08/01/2023] [Accepted: 09/01/2023] [Indexed: 10/12/2023] Open
Abstract
Mobile genetic elements (MGEs) are relevant agents in bacterial adaptation and evolutionary diversification. Stable appropriation of these DNA elements depends on host factors, among which are the nucleoid-associated proteins (NAPs). NAPs are highly abundant proteins that bind and bend DNA, altering its topology and folding, thus affecting all known cellular DNA processes from replication to expression. Even though NAP coding genes are found in most prokaryotic genomes, their functions in host chromosome biology and xenogeneic silencing are only known for a few NAP families. Less is known about the occurrence, abundance, and roles of MGE-encoded NAPs in foreign elements establishment and mobility. In this study, we used a combination of comparative genomics and phylogenetic strategies to gain insights into the diversity, distribution, and functional roles of NAPs within the class Acidithiobacillia with a special focus on their role in MGE biology. Acidithiobacillia class members are aerobic, chemolithoautotrophic, acidophilic sulfur-oxidizers, encompassing substantial genotypic diversity attributable to MGEs. Our search for NAP protein families (PFs) in more than 90 genomes of the different species that conform the class, revealed the presence of 1,197 proteins pertaining to 12 different NAP families, with differential occurrence and conservation across species. Pangenome-level analysis revealed 6 core NAP PFs that were highly conserved across the class, some of which also existed as variant forms of scattered occurrence, in addition to NAPs of taxa-restricted distribution. Core NAPs identified are reckoned as essential based on the conservation of genomic context and phylogenetic signals. In turn, various highly diversified NAPs pertaining to the flexible gene complement of the class, were found to be encoded in known plasmids or, larger integrated MGEs or, present in genomic loci associated with MGE-hallmark genes, pointing to their role in the stabilization/maintenance of these elements in strains and species with larger genomes. Both core and flexible NAPs identified proved valuable as markers, the former accurately recapitulating the phylogeny of the class, and the later, as seed in the bioinformatic identification of novel episomal and integrated mobile elements.
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Affiliation(s)
- Simón Beard
- Centro Científico y Tecnológico de Excelencia Ciencia & Vida, Fundación Ciencia & Vida, Santiago, Chile
- Facultad de Medicina y Ciencia, Universidad San Sebastián, Santiago, Chile
| | - Ana Moya-Beltrán
- Centro Científico y Tecnológico de Excelencia Ciencia & Vida, Fundación Ciencia & Vida, Santiago, Chile
- Facultad de Ingeniería, Arquitectura y Diseño, Universidad San Sebastián, Santiago, Chile
| | - Danitza Silva-García
- Centro Científico y Tecnológico de Excelencia Ciencia & Vida, Fundación Ciencia & Vida, Santiago, Chile
| | - Cesar Valenzuela
- Centro Científico y Tecnológico de Excelencia Ciencia & Vida, Fundación Ciencia & Vida, Santiago, Chile
| | - Tomás Pérez-Acle
- Centro Científico y Tecnológico de Excelencia Ciencia & Vida, Fundación Ciencia & Vida, Santiago, Chile
- Facultad de Medicina y Ciencia, Universidad San Sebastián, Santiago, Chile
- Facultad de Ingeniería, Arquitectura y Diseño, Universidad San Sebastián, Santiago, Chile
| | - Alejandra Loyola
- Centro Científico y Tecnológico de Excelencia Ciencia & Vida, Fundación Ciencia & Vida, Santiago, Chile
- Facultad de Medicina y Ciencia, Universidad San Sebastián, Santiago, Chile
| | - Raquel Quatrini
- Centro Científico y Tecnológico de Excelencia Ciencia & Vida, Fundación Ciencia & Vida, Santiago, Chile
- Facultad de Medicina y Ciencia, Universidad San Sebastián, Santiago, Chile
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7
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Ibáñez A, Garrido-Chamorro S, Coque JJR, Barreiro C. From Genes to Bioleaching: Unraveling Sulfur Metabolism in Acidithiobacillus Genus. Genes (Basel) 2023; 14:1772. [PMID: 37761912 PMCID: PMC10531304 DOI: 10.3390/genes14091772] [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: 08/12/2023] [Revised: 09/04/2023] [Accepted: 09/05/2023] [Indexed: 09/29/2023] Open
Abstract
Sulfur oxidation stands as a pivotal process within the Earth's sulfur cycle, in which Acidithiobacillus species emerge as skillful sulfur-oxidizing bacteria. They are able to efficiently oxidize several reduced inorganic sulfur compounds (RISCs) under extreme conditions for their autotrophic growth. This unique characteristic has made these bacteria a useful tool in bioleaching and biological desulfurization applications. Extensive research has unraveled diverse sulfur metabolism pathways and their corresponding regulatory systems. The metabolic arsenal of the Acidithiobacillus genus includes oxidative enzymes such as: (i) elemental sulfur oxidation enzymes, like sulfur dioxygenase (SDO), sulfur oxygenase reductase (SOR), and heterodisulfide reductase (HDR-like system); (ii) enzymes involved in thiosulfate oxidation pathways, including the sulfur oxidation (Sox) system, tetrathionate hydrolase (TetH), and thiosulfate quinone oxidoreductase (TQO); (iii) sulfide oxidation enzymes, like sulfide:quinone oxidoreductase (SQR); and (iv) sulfite oxidation pathways, such as sulfite oxidase (SOX). This review summarizes the current state of the art of sulfur metabolic processes in Acidithiobacillus species, which are key players of industrial biomining processes. Furthermore, this manuscript highlights the existing challenges and barriers to further exploring the sulfur metabolism of this peculiar extremophilic genus.
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Affiliation(s)
- Ana Ibáñez
- Instituto de Investigación de la Viña y el Vino, Escuela de Ingeniería Agraria, Universidad de León, 24009 León, Spain; (A.I.); (J.J.R.C.)
- Instituto Tecnológico Agrario de Castilla y León (ITACyL), Área de Investigación Agrícola, 47071 Valladolid, Spain
| | - Sonia Garrido-Chamorro
- Área de Bioquímica y Biología Molecular, Departamento de Biología Molecular, Universidad de León, 24007 León, Spain;
| | - Juan J. R. Coque
- Instituto de Investigación de la Viña y el Vino, Escuela de Ingeniería Agraria, Universidad de León, 24009 León, Spain; (A.I.); (J.J.R.C.)
| | - Carlos Barreiro
- Área de Bioquímica y Biología Molecular, Departamento de Biología Molecular, Universidad de León, 24007 León, Spain;
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8
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Ibáñez A, Barreiro C, Diez-Galán A, Cobos R, Calvo-Peña C, Coque JJR. Molecular Identification and Acid Stress Response of an Acidithiobacillus thiooxidans Strain Isolated from Rio Tinto (Spain). Int J Mol Sci 2023; 24:13391. [PMID: 37686204 PMCID: PMC10487802 DOI: 10.3390/ijms241713391] [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: 07/26/2023] [Revised: 08/16/2023] [Accepted: 08/26/2023] [Indexed: 09/10/2023] Open
Abstract
Acidithiobacillus thiooxidans is of paramount importance in the development of biomining technologies. Being widely recognized as an extreme acidophile, extensive research has been dedicated to understanding its significant role in the extraction of several ores in recent years. However, there still exist significant molecular uncertainties surrounding this species. This study focuses on developing a taxonomic assignment method based on the sequencing of the 16S-5S rRNA cluster, along with a qPCR-based technology enabling precise growth determination. Additionally, an approach to understanding its response to acid stress is explored through RT-PCR and MALDI-TOF analysis. Our findings indicate that when subjected to pH levels below 1, the cell inhibits central (carbon fixation and metabolism) and energy (sulfur metabolism) metabolism, as well as chaperone synthesis, suggesting a potential cellular collapse. Nevertheless, the secretion of ammonia is enhanced to raise the environmental pH, while fatty acid synthesis is upregulated to reinforce the cell membrane.
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Affiliation(s)
- Ana Ibáñez
- Instituto de Investigación de la Viña y el Vino, Escuela de Ingeniería Agraria, Universidad de León, 24009 León, Spain; (A.I.); (A.D.-G.); (R.C.); (C.C.-P.)
- Instituto Tecnológico Agrario de Castilla y León (ITACYL), 47071 Valladolid, Spain
| | - Carlos Barreiro
- Área de Bioquímica y Biología Molecular, Departamento de Biología Molecular, Universidad de León, 24071 León, Spain
| | - Alba Diez-Galán
- Instituto de Investigación de la Viña y el Vino, Escuela de Ingeniería Agraria, Universidad de León, 24009 León, Spain; (A.I.); (A.D.-G.); (R.C.); (C.C.-P.)
| | - Rebeca Cobos
- Instituto de Investigación de la Viña y el Vino, Escuela de Ingeniería Agraria, Universidad de León, 24009 León, Spain; (A.I.); (A.D.-G.); (R.C.); (C.C.-P.)
| | - Carla Calvo-Peña
- Instituto de Investigación de la Viña y el Vino, Escuela de Ingeniería Agraria, Universidad de León, 24009 León, Spain; (A.I.); (A.D.-G.); (R.C.); (C.C.-P.)
| | - Juan José R. Coque
- Instituto de Investigación de la Viña y el Vino, Escuela de Ingeniería Agraria, Universidad de León, 24009 León, Spain; (A.I.); (A.D.-G.); (R.C.); (C.C.-P.)
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9
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Jones S, Santini JM. Mechanisms of bioleaching: iron and sulfur oxidation by acidophilic microorganisms. Essays Biochem 2023; 67:685-699. [PMID: 37449416 PMCID: PMC10427800 DOI: 10.1042/ebc20220257] [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: 04/30/2023] [Revised: 06/20/2023] [Accepted: 06/21/2023] [Indexed: 07/18/2023]
Abstract
Bioleaching offers a low-input method of extracting valuable metals from sulfide minerals, which works by exploiting the sulfur and iron metabolisms of microorganisms to break down the ore. Bioleaching microbes generate energy by oxidising iron and/or sulfur, consequently generating oxidants that attack sulfide mineral surfaces, releasing target metals. As sulfuric acid is generated during the process, bioleaching organisms are typically acidophiles, and indeed the technique is based on natural processes that occur at acid mine drainage sites. While the overall concept of bioleaching appears straightforward, a series of enzymes is required to mediate the complex sulfur oxidation process. This review explores the mechanisms underlying bioleaching, summarising current knowledge on the enzymes driving microbial sulfur and iron oxidation in acidophiles. Up-to-date models are provided of the two mineral-defined pathways of sulfide mineral bioleaching: the thiosulfate and the polysulfide pathway.
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Affiliation(s)
- Sarah Jones
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, WC1E 6BT, U.K
- Institute of Structural and Molecular Biology, Division of Biosciences, Birkbeck, University of London, Malet Street, London, WC1E 7HX, U.K
| | - Joanne M Santini
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, WC1E 6BT, U.K
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10
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Chen J, Liu Y, Diep P, Mahadevan R. Genetic engineering of extremely acidophilic Acidithiobacillus species for biomining: Progress and perspectives. JOURNAL OF HAZARDOUS MATERIALS 2022; 438:129456. [PMID: 35777147 DOI: 10.1016/j.jhazmat.2022.129456] [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: 04/12/2022] [Revised: 06/19/2022] [Accepted: 06/22/2022] [Indexed: 06/15/2023]
Abstract
With global demands for mineral resources increasing and ore grades decreasing, microorganisms have been increasingly deployed in biomining applications to recover valuable metals particularly from normally considered waste, such as low-grade ores and used consumer electronics. Acidithiobacillus are a genus of chemolithoautotrophic extreme acidophiles that are commonly found in mining process waters and acid mine drainage, which have been reported in several studies to aid in metal recovery from bioremediation of metal-contaminated sites. Compared to conventional mineral processing technologies, biomining is often cited as a more sustainable and environmentally friendly process, but long leaching cycles and low extraction efficiency are main disadvantages that have hampered its industrial applications. Genetic engineering is a powerful technology that can be used to enhance the performance of microorganisms, such as Acidithiobacillus species. In this review, we compile existing data on Acidithiobacillus species' physiological traits and genomic characteristics, progresses in developing genetic tools to engineer them: plasmids, shutter vectors, transformation methods, selection markers, promoters and reporter systems developed, and genome editing techniques. We further propose genetic engineering strategies for enhancing biomining efficiency of Acidithiobacillus species and provide our perspectives on their future applications.
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Affiliation(s)
- Jinjin Chen
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Canada
| | - Yilan Liu
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Canada
| | - Patrick Diep
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Canada
| | - Radhakrishnan Mahadevan
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Canada; Institute of Biomedical Engineering, University of Toronto, Toronto, Canada.
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Azizitorghabeh A, Mahandra H, Ramsay J, Ghahreman A. A sustainable approach for gold recovery from refractory source using novel BIOX-TC system. J IND ENG CHEM 2022. [DOI: 10.1016/j.jiec.2022.08.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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12
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Javier RA, Matías R, Alonso F, Renato C, Gloria L. A novel gene from the acidophilic bacterium Leptospirillum sp. CF-1 and its role in oxidative stress and chromate tolerance. Biol Res 2022; 55:19. [PMID: 35525996 PMCID: PMC9080137 DOI: 10.1186/s40659-022-00388-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 04/15/2022] [Indexed: 11/16/2022] Open
Abstract
Background Acidophilic microorganisms like Leptospirillum sp. CF-1 thrive in environments with extremely low pH and high concentrations of dissolved heavy metals that can induce the generation of reactive oxygen species (ROS). Several hypothetical genes and proteins from Leptospirillum sp. CF-1 are known to be up-regulated under oxidative stress conditions. Results In the present work, the function of hypothetical gene ABH19_09590 from Leptospirillum sp. CF-1 was studied. Heterologous expression of this gene in Escherichia coli led to an increase in the ability to grow under oxidant conditions with 5 mM K2CrO4 or 5 mM H2O2. Similarly, a significant reduction in ROS production in E. coli transformed with a plasmid carrying ABH19_09590 was observed after exposure to these oxidative stress elicitors for 30 min, compared to a strain complemented with the empty vector. A co-transcriptional study using RT-PCR showed that ABH19_09590 is contained in an operon, here named the “och” operon, that also contains ABH19_09585, ABH19_09595 and ABH19_09600 genes. The expression of the och operon was significantly up-regulated in Leptospirillum sp. CF-1 exposed to 5 mM K2CrO4 for 15 and 30 min. Genes of this operon potentially encode a NADH:ubiquinone oxidoreductase, a CXXC motif-containing protein likely involved in thiol/disulfide exchange, a hypothetical protein, and a di-hydroxy-acid dehydratase. A comparative genomic analysis revealed that the och operon is a characteristic genetic determinant of the Leptospirillum genus that is not present in other acidophiles. Conclusions Altogether, these results suggest that the och operon plays a protective role against chromate and hydrogen peroxide and is an important mechanism required to face polyextremophilic conditions in acid environments.
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Affiliation(s)
- Rivera-Araya Javier
- Biology Department, Faculty of Chemistry and Biology, University of Santiago of Chile (USACH), Santiago, Chile
| | - Riveros Matías
- Biology Department, Faculty of Chemistry and Biology, University of Santiago of Chile (USACH), Santiago, Chile
| | - Ferrer Alonso
- Núcleo de Química y Bioquímica, Facultad de Ciencias, Universidad Mayor, Santiago, Chile
| | - Chávez Renato
- Biology Department, Faculty of Chemistry and Biology, University of Santiago of Chile (USACH), Santiago, Chile
| | - Levicán Gloria
- Biology Department, Faculty of Chemistry and Biology, University of Santiago of Chile (USACH), Santiago, Chile.
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13
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He Y, Guo J, Song Y, Chen Z, Lu C, Han Y, Li H, Hou Y. Te(IV) bioreduction in the sulfur autotrophic reactor: Performance, kinetics and synergistic mechanism. WATER RESEARCH 2022; 214:118216. [PMID: 35228038 DOI: 10.1016/j.watres.2022.118216] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 02/12/2022] [Accepted: 02/18/2022] [Indexed: 06/14/2023]
Abstract
A laboratory-scale sulfur autotrophic reactor (SAR) was first constructed for treating tellurite [Te(IV)] wastewater. The SAR had excellent Te(IV) bioreduction efficiency (90-96%) at 5-30 mg/L and conformed to the First-order kinetic model. The Te(IV) bioreduction was elaborated deeply from extracellular polymeric substances (EPS) functions, microbial metabolic activity, key enzyme activity, microbial community succession and quorum sensing. Te(IV) stimulated the increase of redox substances in EPS and the improved cell membrane permeability led to the increase of electron transport system activity. Catalase and reduced nicotinamide adenine dinucleotide (NADH) alleviated the oxidative stress caused by Te(IV) toxicity to maintain metabolic activity. The increase of sulfur dioxygenase activity (SDO) suggested that more ATP produced by sulfur oxidation might provide energy for various physiological activities. Meanwhile, nitrate reductase (NAR), nitrite reductase (NIR) and sulfide: quinone oxidoreductase (SQR) played an active role in sulfur oxidation and Te(IV) bioreduction. Combined with the above results and dynamic succession of three functional microbial communities, a synergistic mechanism was proposed to explain the excellent performance of SAR. This work provided a promising strategy for Te(IV) wastewater treatment process and Te(IV) bioreduction mechanism.
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Affiliation(s)
- Yue He
- School of Environmental and Municipal Engineering, Tianjin Key Laboratory of Aquatic Science and Technology, Tianjin Chengjian University, Jinjing Road 26, Tianjin 300384, China
| | - Jianbo Guo
- School of Civil Engineering and Architecture, Taizhou University, Taizhou 318000, Zhejiang, China; School of Environmental and Municipal Engineering, Tianjin Key Laboratory of Aquatic Science and Technology, Tianjin Chengjian University, Jinjing Road 26, Tianjin 300384, China.
| | - Yuanyuan Song
- School of Environmental and Municipal Engineering, Tianjin Key Laboratory of Aquatic Science and Technology, Tianjin Chengjian University, Jinjing Road 26, Tianjin 300384, China
| | - Zhi Chen
- Department of Building, Civil, and Environmental Engineering, Concordia University, 1455 de Maisonneuve Blvd. W. Montreal, Quebec, Canada
| | - Caicai Lu
- School of Environmental and Municipal Engineering, Tianjin Key Laboratory of Aquatic Science and Technology, Tianjin Chengjian University, Jinjing Road 26, Tianjin 300384, China
| | - Yi Han
- School of Environmental and Municipal Engineering, Tianjin Key Laboratory of Aquatic Science and Technology, Tianjin Chengjian University, Jinjing Road 26, Tianjin 300384, China
| | - Haibo Li
- School of Environmental and Municipal Engineering, Tianjin Key Laboratory of Aquatic Science and Technology, Tianjin Chengjian University, Jinjing Road 26, Tianjin 300384, China
| | - Yanan Hou
- School of Environmental and Municipal Engineering, Tianjin Key Laboratory of Aquatic Science and Technology, Tianjin Chengjian University, Jinjing Road 26, Tianjin 300384, China
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14
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González-Rosales C, Vergara E, Dopson M, Valdés JH, Holmes DS. Integrative Genomics Sheds Light on Evolutionary Forces Shaping the Acidithiobacillia Class Acidophilic Lifestyle. Front Microbiol 2022; 12:822229. [PMID: 35242113 PMCID: PMC8886135 DOI: 10.3389/fmicb.2021.822229] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Accepted: 12/30/2021] [Indexed: 01/22/2023] Open
Abstract
Extreme acidophiles thrive in environments rich in protons (pH values <3) and often high levels of dissolved heavy metals. They are distributed across the three domains of the Tree of Life including members of the Proteobacteria. The Acidithiobacillia class is formed by the neutrophilic genus Thermithiobacillus along with the extremely acidophilic genera Fervidacidithiobacillus, Igneacidithiobacillus, Ambacidithiobacillus, and Acidithiobacillus. Phylogenomic reconstruction revealed a division in the Acidithiobacillia class correlating with the different pH optima that suggested that the acidophilic genera evolved from an ancestral neutrophile within the Acidithiobacillia. Genes and mechanisms denominated as "first line of defense" were key to explaining the Acidithiobacillia acidophilic lifestyle including preventing proton influx that allows the cell to maintain a near-neutral cytoplasmic pH and differ from the neutrophilic Acidithiobacillia ancestors that lacked these systems. Additional differences between the neutrophilic and acidophilic Acidithiobacillia included the higher number of gene copies in the acidophilic genera coding for "second line of defense" systems that neutralize and/or expel protons from cell. Gain of genes such as hopanoid biosynthesis involved in membrane stabilization at low pH and the functional redundancy for generating an internal positive membrane potential revealed the transition from neutrophilic properties to a new acidophilic lifestyle by shaping the Acidithiobacillaceae genomic structure. The presence of a pool of accessory genes with functional redundancy provides the opportunity to "hedge bet" in rapidly changing acidic environments. Although a core of mechanisms for acid resistance was inherited vertically from an inferred neutrophilic ancestor, the majority of mechanisms, especially those potentially involved in resistance to extremely low pH, were obtained from other extreme acidophiles by horizontal gene transfer (HGT) events.
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Affiliation(s)
- Carolina González-Rosales
- Center for Bioinformatics and Genome Biology, Centro Ciencia & Vida, Fundación Ciencia & Vida, Santiago, Chile.,Center for Genomics and Bioinformatics, Faculty of Sciences, Universidad Mayor, Santiago, Chile
| | - Eva Vergara
- Center for Bioinformatics and Genome Biology, Centro Ciencia & Vida, Fundación Ciencia & Vida, Santiago, Chile
| | - Mark Dopson
- Centre for Ecology and Evolution in Microbial Model Systems, Linnaeus University, Kalmar, Sweden
| | - Jorge H Valdés
- Center for Bioinformatics and Integrative Biology, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile
| | - David S Holmes
- Center for Bioinformatics and Genome Biology, Centro Ciencia & Vida, Fundación Ciencia & Vida, Santiago, Chile.,Facultad de Medicina y Ciencia, Universidad San Sebastián, Santiago, Chile
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15
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Fang X, Sun S, Liao X, Li S, Zhou S, Gan Q, Zeng L, Guan Z. Effect of diurnal temperature range on bioleaching of sulfide ore by an artificial microbial consortium. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 806:150234. [PMID: 34562759 DOI: 10.1016/j.scitotenv.2021.150234] [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: 06/18/2021] [Revised: 08/28/2021] [Accepted: 09/05/2021] [Indexed: 06/13/2023]
Abstract
Temperature is considered to be one of the main factors affecting bioleaching, but few studies have assessed the effects of diurnal temperature range (DTR) on the bioleaching process. This study investigates the effects of different bioleaching temperatures (30 and 40 °C) and DTR on the bioleaching of metal sulfide ores by microbial communities. The results showed that DTR had an obvious inhibitory effect on the bioleaching efficiency of the artificial microbial community, although this effect was mainly concentrated in the early and middle stages (0-18 days) of exposure, gradually decreasing until almost disappearing in the late stage (18-24 days). Extracellular polymeric substance (EPS) analysis showed that DTR did not change the composition of the EPS matrix (humic acid-like substances, polysaccharides and protein-like substances), but had a significant effect on the generative behavior of EPS, inhibiting the secretion of EPS during the early and middle stages of the bioleaching process. However, the continual increase in EPS secretion in the bioleaching system gradually reduced the adverse effects of DTR on mineral dissolution. X-ray diffraction (XRD), Fourier transform infrared (FTIR) and Scanning electron microscopy- energy dispersive spectrometry (SEM-EDS) analysis of the bioleached residue showed that DTR had no obvious effect on the mineralogical characteristics of sulfide ore. Therefore, in industrial sulfide ore bioleaching applications, in order to accelerate the artificial microbial community start-up process, temperature control measures should be increased in the bioleaching process to reduce the adverse effects of DTR on mineral dissolution.
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Affiliation(s)
- Xiaodi Fang
- Guangzhou Key Laboratory Environmental Catalysis and Pollution Control, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, School of Environmental Science and Engineering, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou 510006, China
| | - Shuiyu Sun
- Guangzhou Key Laboratory Environmental Catalysis and Pollution Control, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, School of Environmental Science and Engineering, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou 510006, China; Guangdong Polytechnic of Environmental Protection Engineering, Foshan 528216, China
| | - Xiaojian Liao
- Guangzhou Key Laboratory Environmental Catalysis and Pollution Control, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, School of Environmental Science and Engineering, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou 510006, China
| | - Shoupeng Li
- Guangzhou Key Laboratory Environmental Catalysis and Pollution Control, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, School of Environmental Science and Engineering, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou 510006, China.
| | - Siyu Zhou
- Guangzhou Key Laboratory Environmental Catalysis and Pollution Control, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, School of Environmental Science and Engineering, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou 510006, China
| | - Qiaowei Gan
- Guangzhou Key Laboratory Environmental Catalysis and Pollution Control, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, School of Environmental Science and Engineering, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou 510006, China
| | - Liuting Zeng
- Guangzhou Key Laboratory Environmental Catalysis and Pollution Control, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, School of Environmental Science and Engineering, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou 510006, China
| | - Zhijie Guan
- Guangzhou Key Laboratory Environmental Catalysis and Pollution Control, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, School of Environmental Science and Engineering, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou 510006, China
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16
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Li M, Wen J. Recent progress in the application of omics technologies in the study of bio-mining microorganisms from extreme environments. Microb Cell Fact 2021; 20:178. [PMID: 34496835 PMCID: PMC8425152 DOI: 10.1186/s12934-021-01671-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2021] [Accepted: 08/30/2021] [Indexed: 11/11/2022] Open
Abstract
Bio-mining microorganisms are a key factor affecting the metal recovery rate of bio-leaching, which inevitably produces an extremely acidic environment. As a powerful tool for exploring the adaptive mechanisms of microorganisms in extreme environments, omics technologies can greatly aid our understanding of bio-mining microorganisms and their communities on the gene, mRNA, and protein levels. These omics technologies have their own advantages in exploring microbial diversity, adaptive evolution, changes in metabolic characteristics, and resistance mechanisms of single strains or their communities to extreme environments. These technologies can also be used to discover potential new genes, enzymes, metabolites, metabolic pathways, and species. In addition, integrated multi-omics analysis can link information at different biomolecular levels, thereby obtaining more accurate and complete global adaptation mechanisms of bio-mining microorganisms. This review introduces the current status and future trends in the application of omics technologies in the study of bio-mining microorganisms and their communities in extreme environments.
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Affiliation(s)
- Min Li
- Key Laboratory of Systems Bioengineering, Tianjin University, Tianjin, China.,Collaborative Innovation Center of Chemical Science and Engineering, Tianjin University, Tianjin, China.,Frontier Science Center of Ministry of Education, Tianjin University, Tianjin, China
| | - Jianping Wen
- Key Laboratory of Systems Bioengineering, Tianjin University, Tianjin, China. .,Collaborative Innovation Center of Chemical Science and Engineering, Tianjin University, Tianjin, China. .,Frontier Science Center of Ministry of Education, Tianjin University, Tianjin, China.
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Willard DJ, Kelly RM. Intersection of Biotic and Abiotic Sulfur Chemistry Supporting Extreme Microbial Life in Hot Acid. J Phys Chem B 2021; 125:5243-5257. [PMID: 33979170 PMCID: PMC10562994 DOI: 10.1021/acs.jpcb.1c02102] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Microbial life on Earth exists within wide ranges of temperature, pressure, pH, salinity, radiation, and water activity. Extreme thermoacidophiles, in particular, are microbes found in hot, acidic biotopes laden with heavy metals and reduced inorganic sulfur species. As chemolithoautotrophs, they thrive in the absence of organic carbon, instead using sulfur and metal oxidation to fuel their bioenergetic needs, while incorporating CO2 as a carbon source. Metal oxidation by these microbes takes place extracellularly, mediated by membrane-associated oxidase complexes. In contrast, sulfur oxidation involves extracellular, membrane-associated, and cytoplasmic biotransformations, which intersect with abiotic sulfur chemistry. This novel lifestyle has been examined in the context of early aerobic life on this planet, but it is also interesting when considering the prospects of life, now or previously, on other solar bodies. Here, extreme thermoacidophily (growth at pH below 4.0, temperature above 55 °C), a characteristic of species in the archaeal order Sulfolobales, is considered from the perspective of sulfur chemistry, both biotic and abiotic, as it relates to microbial bioenergetics. Current understanding of the mechanisms involved are reviewed which are further expanded through recent experimental results focused on imparting sulfur oxidation capacity on a natively nonsulfur oxidizing extremely thermoacidophilic archaeon, Sulfolobus acidocaldarius, through metabolic engineering.
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Affiliation(s)
- Daniel J. Willard
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27695
| | - Robert M. Kelly
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27695
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18
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Jung T, Hackbarth M, Horn H, Gescher J. Improving the Cathodic Biofilm Growth Capabilities of Kyrpidia spormannii EA-1 by Undirected Mutagenesis. Microorganisms 2020; 9:microorganisms9010077. [PMID: 33396703 PMCID: PMC7823960 DOI: 10.3390/microorganisms9010077] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 12/23/2020] [Accepted: 12/25/2020] [Indexed: 12/18/2022] Open
Abstract
The biotechnological usage of carbon dioxide has become a relevant aim for future processes. Microbial electrosynthesis is a rather new technique to energize biological CO2 fixation with the advantage to establish a continuous process based on a cathodic biofilm that is supplied with renewable electrical energy as electron and energy source. In this study, the recently characterized cathodic biofilm forming microorganism Kyrpidia spormannii strain EA-1 was used in an adaptive laboratory evolution experiment to enhance its cathodic biofilm growth capabilities. At the end of the experiment, the adapted cathodic population exhibited an up to fourfold higher biofilm accumulation rate, as well as faster substratum coverage and a more uniform biofilm morphology compared to the progenitor strain. Genomic variant analysis revealed a genomically heterogeneous population with genetic variations occurring to various extends throughout the community. Via the conducted analysis we identified possible targets for future genetic engineering with the aim to further optimize cathodic growth. Moreover, the results assist in elucidating the underlying processes that enable cathodic biofilm formation.
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Affiliation(s)
- Tobias Jung
- Department of Applied Biology, Institute for Applied Biosciences, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 2, 76131 Karlsruhe, Germany
| | - Max Hackbarth
- Engler-Bunte-Institut, Chair of Water Chemistry and Water Technology, Karlsruhe Institute of Technology (KIT), Engler-Bunte-Ring 9, 76131 Karlsruhe, Germany
| | - Harald Horn
- Engler-Bunte-Institut, Chair of Water Chemistry and Water Technology, Karlsruhe Institute of Technology (KIT), Engler-Bunte-Ring 9, 76131 Karlsruhe, Germany
| | - Johannes Gescher
- Department of Applied Biology, Institute for Applied Biosciences, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 2, 76131 Karlsruhe, Germany
- Institute for Biological Interfaces, Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
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