1
|
Tejedor-Sanz S, Li S, Kundu BB, Ajo-Franklin CM. Extracellular electron uptake from a cathode by the lactic acid bacterium Lactiplantibacillus plantarum. Front Microbiol 2023; 14:1298023. [PMID: 38075918 PMCID: PMC10701730 DOI: 10.3389/fmicb.2023.1298023] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Accepted: 11/03/2023] [Indexed: 01/28/2024] Open
Abstract
A subset of microorganisms that perform respiration can endogenously utilize insoluble electron donors, such as Fe(II) or a cathode, in a process called extracellular electron transfer (EET). However, it is unknown whether similar endogenous EET can be performed by primarily fermentative species like lactic acid bacteria. We report for the first time electron uptake from a cathode by Lactiplantibacillus plantarum, a primarily fermentative bacteria found in the gut of mammals and in fermented foods. L. plantarum consumed electrons from a cathode and coupled this oxidation to the reduction of both an endogenous organic (pyruvate) and an exogenous inorganic electron acceptor (nitrate). This electron uptake from a cathode reroutes glucose fermentation toward lactate degradation and provides cells with a higher viability upon sugar exhaustion. Moreover, the associated genes and cofactors indicate that this activity is mechanistically different from that one employed by lactic acid bacteria to reduce an anode and to perform respiration. Our results expand our knowledge of the diversity of electroactive species and of the metabolic and bioenergetic strategies used by lactic acid bacteria.
Collapse
Affiliation(s)
- Sara Tejedor-Sanz
- Department of BioSciences, Rice University, Houston, TX, United States
- Biological Nanostructures Facility, The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
| | - Siliang Li
- Department of BioSciences, Rice University, Houston, TX, United States
| | - Biki Bapi Kundu
- PhD Program in Systems, Synthetic, and Physical Biology, Rice University, Houston, TX, United States
| | - Caroline M. Ajo-Franklin
- Department of BioSciences, Rice University, Houston, TX, United States
- Biological Nanostructures Facility, The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
- Department of Bioengineering, Rice University, Houston, TX, United States
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, TX, United States
| |
Collapse
|
2
|
Yadav S, Sadhotra C, Patil SA. Retracted: The bidirectional extracellular electron transfer process aids iron cycling by Geoalkalibacter halelectricus in a highly saline-alkaline condition. Appl Environ Microbiol 2023:e0060923. [PMID: 37681980 DOI: 10.1128/aem.00609-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Accepted: 07/16/2023] [Indexed: 09/09/2023] Open
Abstract
Bidirectional extracellular electron transfer (EET) is crucial to upholding microbial metabolism with insoluble electron acceptors or donors in anoxic environments. Investigating bidirectional EET-capable microorganisms is desired to understand the cell-cell and microbe-mineral interactions and their role in mineral cycling besides leveraging their energy generation and conversion, biosensing, and bio-battery applications. Here, we report on iron cycling by haloalkaliphilic Geoalkalibacter halelectricus via bidirectional EET under haloalkaline conditions. It efficiently reduces Fe3+ oxide (Fe2O3) to Fe0 at a 0.75 ± 0.08 mM/mgprotein/d rate linked to acetate oxidation via outward EET and oxidizes Fe0 to Fe3+ at a 0.24 ± 0.03 mM/mgprotein/d rate via inward EET to reduce fumarate. Bioelectrochemical cultivation confirmed its outward and inward EET capabilities. It produced 895 ± 23 µA/cm2 current by linking acetate oxidation to anode reduction via outward EET and reduced fumarate by drawing electrons from the cathode (‒2.5 ± 0.3 µA/cm2) via inward EET. The cyclic voltammograms of G. halelectricus biofilms revealed redox moieties with different formal potentials, suggesting the involvement of different membrane components in bidirectional EET. The cyclic voltammetry and GC-MS analysis of the cell-free spent medium revealed the lack of soluble redox mediators, suggesting direct electron transfer by G. halelecctricus in achieving bidirectional EET. By reporting on the first haloalkaliphilic bacterium capable of oxidizing and reducing insoluble Fe0 and Fe3+ oxide, respectively, this study advances the limited understanding of the metabolic capabilities of extremophiles to respire on insoluble electron acceptors or donors via bidirectional EET and invokes the possible role of G. halelectricus in iron cycling in barely studied haloalkaline environments. IMPORTANCE Bidirectional extracellular electron transfer (EET) appears to be a key microbial metabolic process in anoxic environments that are depleted in soluble electron donor and acceptor molecules. Though it is an ecologically important and applied microbial phenomenon, it has been reported with a few microorganisms, mostly from nonextreme environments. Moreover, direct electron transfer-based bidirectional EET is studied for very few microorganisms with electrodes in engineered systems and barely with the natural insoluble electron acceptor and donor molecules in anoxic conditions. This study advances the understanding of extremophilic microbial taxa capable of bidirectional EET and its role in barely investigated Fe cycling in highly saline-alkaline environments. It also offers research opportunities for understanding the membrane components involved in the bidirectional EET of G. halelectricus. The high rate of Fe3+ oxide reduction activity by G. halelectricus suggests its possible use as a biocatalyst in the anaerobic iron bioleaching process under neutral-alkaline pH conditions.
Collapse
Affiliation(s)
- Sukrampal Yadav
- Department of Earth and Environmental Sciences, Indian Institute of Science Education and Research Mohali (IISER Mohali) , Knowledge City, Punjab, India
| | - Chetan Sadhotra
- Department of Earth and Environmental Sciences, Indian Institute of Science Education and Research Mohali (IISER Mohali) , Knowledge City, Punjab, India
| | - Sunil A Patil
- Department of Earth and Environmental Sciences, Indian Institute of Science Education and Research Mohali (IISER Mohali) , Knowledge City, Punjab, India
| |
Collapse
|
3
|
Electrochemical performance of Paenibacillus profundus YoMME encapsulated in alginate polymer. Bioelectrochemistry 2023; 150:108354. [PMID: 36563455 DOI: 10.1016/j.bioelechem.2022.108354] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 12/12/2022] [Accepted: 12/15/2022] [Indexed: 12/23/2022]
Abstract
Gram-positive bacterium Paenibacillus profundus YoMME, entrapped in an alginate polymer onto graphite paper, preserves its extracellular electron transfer capabilities. A current density of up to 30 mA m-2 was generated at an applied potential of -200 mV (vs. SHE). Fivefold higher initial current density values were recorded at applied potentials of +220 mV and +600 mV. The electrochemical behavior of the encapsulated bioelectrodes has been also explored by cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy and evaluated by the parameters of the best-fitted equivalent electric circuit model. Over time the bacteria grow and divide within the alginate matrix, which affects considerably the capacitance and the charge transfer resistance of the coating. The impedance spectra follow the dynamics of the bacterial culture development within the alginate polymer and are useful for the prediction of the bioelectrode performance. A current density of 150 mA m-2 was achieved when the alginate was functionalized by a mixture of the redox dyes thiazolyl blue (MTT) formazan and phenazine methosulfate (PMS). It is supposed that the added artificial mediators facilitate the electron transfer from the bacteria to the electrode surface by forming conductive cascade conduits through the alginate matrix.
Collapse
|
4
|
Cantillo-González A, Anguita J, Rojas C, Vargas IT. Winogradsky Bioelectrochemical System as a Novel Strategy to Enrich Electrochemically Active Microorganisms from Arsenic-Rich Sediments. MICROMACHINES 2022; 13:1953. [PMID: 36422381 PMCID: PMC9692521 DOI: 10.3390/mi13111953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 10/12/2022] [Accepted: 10/28/2022] [Indexed: 06/16/2023]
Abstract
Bioelectrochemical systems (BESs) have been extensively studied for treatment and remediation. However, BESs have the potential to be used for the enrichment of microorganisms that could replace their natural electron donor or acceptor for an electrode. In this study, Winogradsky BES columns with As-rich sediments extracted from an Andean watershed were used as a strategy to enrich lithotrophic electrochemically active microorganisms (EAMs) on electrodes (i.e., cathodes). After 15 months, Winogradsky BESs registered power densities up to 650 μWcm-2. Scanning electron microscopy and linear sweep voltammetry confirmed microbial growth and electrochemical activity on cathodes. Pyrosequencing evidenced differences in bacterial composition between sediments from the field and cathodic biofilms. Six EAMs from genera Herbaspirillum, Ancylobacter, Rhodococcus, Methylobacterium, Sphingomonas, and Pseudomonas were isolated from cathodes using a lithoautotrophic As oxidizers culture medium. These results suggest that the tested Winogradsky BES columns result in an enrichment of electrochemically active As-oxidizing microorganisms. A bioelectrochemical boost of centenarian enrichment approaches, such as the Winogradsky column, represents a promising strategy for prospecting new EAMs linked with the biogeochemical cycles of different metals and metalloids.
Collapse
Affiliation(s)
- Angela Cantillo-González
- Departmento de Ingeniería Hidráulica y Ambiental, Pontificia Universidad Católica de Chile, Santiago 7820436, Chile
- Centro de Desarrollo Urbano Sustentable (CEDEUS), Santiago 6640064, Chile
| | - Javiera Anguita
- Departmento de Ingeniería Hidráulica y Ambiental, Pontificia Universidad Católica de Chile, Santiago 7820436, Chile
| | - Claudia Rojas
- Laboratory of Soil Microbial Ecology and Biogeochemistry (LEMiBiS), Institute of Agri-Food, Animal and Environmental Sciences (ICA3), Universidad de O’Higgins, San Fernando 3070000, Chile
- Center of Applied Ecology and Sustainability (CAPES), Santiago 8331150, Chile
| | - Ignacio T. Vargas
- Departmento de Ingeniería Hidráulica y Ambiental, Pontificia Universidad Católica de Chile, Santiago 7820436, Chile
- Centro de Desarrollo Urbano Sustentable (CEDEUS), Santiago 6640064, Chile
| |
Collapse
|
5
|
Conservation of Energetic Pathways for Electroautotrophy in the Uncultivated Candidate Order Tenderiales. mSphere 2022; 7:e0022322. [PMID: 36069437 PMCID: PMC9599434 DOI: 10.1128/msphere.00223-22] [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] [Indexed: 11/20/2022] Open
Abstract
Electromicrobiology can be used to understand extracellular electron uptake in previously undescribed chemolithotrophs. Enrichment and characterization of the uncultivated electroautotroph "Candidatus Tenderia electrophaga" using electromicrobiology led to the designation of the order Tenderiales. Representative Tenderiales metagenome-assembled genomes (MAGs) have been identified in a number of environmental surveys, yet a comprehensive characterization of conserved genes for extracellular electron uptake has thus far not been conducted. Using comparative genomics, we identified conserved orthologous genes within the Tenderiales and nearest-neighbor orders important for extracellular electron uptake based on a previously proposed pathway from "Ca. Tenderia electrophaga." The Tenderiales contained a conserved cluster we designated uetABCDEFGHIJ, which encodes proteins containing features that would enable transport of extracellular electrons to cytoplasmic membrane-bound energy-transducing complexes such as two conserved cytochrome cbb3 oxidases. For example, UetJ is predicted to be an extracellular undecaheme c-type cytochrome that forms a heme wire. We also identified clusters of genes predicted to facilitate assembly and maturation of electron transport proteins, as well as cellular attachment to surfaces. Autotrophy among the Tenderiales is supported by the presence of carbon fixation and stress response pathways that could allow cellular growth by extracellular electron uptake. Key differences between the Tenderiales and other known neutrophilic iron oxidizers were revealed, including very few Cyc2 genes in the Tenderiales. Our results reveal a possible conserved pathway for extracellular electron uptake and suggest that the Tenderiales have an ecological role in coupling metal or mineral redox chemistry and the carbon cycle in marine and brackish sediments. IMPORTANCE Chemolithotrophic bacteria capable of extracellular electron uptake to drive energy metabolism and CO2 fixation are known as electroautotrophs. The recently described order Tenderiales contains the uncultivated electroautotroph "Ca. Tenderia electrophaga." The "Ca. Tenderia electrophaga" genome contains genes proposed to make up a previously undescribed extracellular electron uptake pathway. Here, we use comparative genomics to show that this pathway is well conserved among Tenderiales spp. recovered by metagenome-assembled genomes. This conservation extends to near neighbors of the Tenderiales but not to other well-studied chemolithotrophs, including iron and sulfur oxidizers, indicating that these genes may be useful markers of growth using insoluble extracellular electron donors. Our findings suggest that extracellular electron uptake and electroautotrophy may be pervasive among the Tenderiales, and the geographic locations from which metagenome-assembled genomes were recovered offer clues to their natural ecological niche.
Collapse
|
6
|
Luo X, Huang L, Cai X, Zhou L, Zhou S, Yuan Y. Structure and core taxa of bacterial communities involved in extracellular electron transfer in paddy soils across China. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 844:157196. [PMID: 35810886 DOI: 10.1016/j.scitotenv.2022.157196] [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: 04/19/2022] [Revised: 06/25/2022] [Accepted: 07/02/2022] [Indexed: 06/15/2023]
Abstract
Microbial communities with extracellular electron transfer (EET) activity are capable of driving geochemical changes and cycles, but a comprehensive understanding of the key microbiota responsible for EET in complex soil matrices is still lacking. Herein, the EET activities, in terms of maximum current density (jmax) and accumulated charge output (Cout), of 41 paddy soils across China were evaluated from the exoelectrogenic properties with a conventional bioelectrochemical system (BES). The jmax with a range of 8.85 × 10-4 to 0.41 A/m2 and Cout with a range of 0.27 to 172.21C were obtained from these soil-based BESs. The bacterial community analyses revealed that the most abundant phylum, order, and genus were Firmicutes, Clostridiales, and Clostridum-sensus-stricto 10, respectively. Bacterial network analysis displayed the positive correlations between the majority of electroactive bacteria-containing genera and multiple other genera, indicating their underlying cooperation for the EET. Partial least squares regression (PLSR) model showed remarkable performance in describing the EET activity with 75 most abundant genera as input variables, identified that 32 genera were very important for governing the EET activities. Multiple linear regression (MLR) analyses further prioritized that the genera norank-c-Berkelbacteria and Fonticella were the key contributors, while the genus Paenibacillus was the key competitor against bacterial exoelectrogenesis in paddy soils. Moreover, the spearman analysis showed that the abundance of these keystone taxa was mainly influenced by the carbon content and pH. This approach provides a promising avenue to monitor the microbial activities in paddy soils as well as the links between microbial community composition and ecological function.
Collapse
Affiliation(s)
- Xiaoshan Luo
- Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, Guangzhou Key Laboratory Environmental Catalysis and Pollution Control, School of Environmental Science and Engineering, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou 510006, China
| | - Lingyan Huang
- Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, Guangzhou Key Laboratory Environmental Catalysis and Pollution Control, School of Environmental Science and Engineering, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou 510006, China
| | - Xixi Cai
- Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, Guangzhou Key Laboratory Environmental Catalysis and Pollution Control, School of Environmental Science and Engineering, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou 510006, China
| | - Lihua Zhou
- Department of Pharmaceutical Engineering, School of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Guangzhou 510006, China
| | - Shungui Zhou
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, School of Resources and Environment, Fujian Agriculture and Forestry, Fuzhou 350000, China
| | - Yong Yuan
- Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, Guangzhou Key Laboratory Environmental Catalysis and Pollution Control, School of Environmental Science and Engineering, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou 510006, China.
| |
Collapse
|
7
|
Sackett JD, Kamble N, Leach E, Schuelke T, Wilbanks E, Rowe AR. Genome-Scale Mutational Analysis of Cathode-Oxidizing Thioclava electrotropha ElOx9 T. Front Microbiol 2022; 13:909824. [PMID: 35756027 PMCID: PMC9226611 DOI: 10.3389/fmicb.2022.909824] [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: 03/31/2022] [Accepted: 05/17/2022] [Indexed: 11/13/2022] Open
Abstract
Extracellular electron transfer (EET) – the process by which microorganisms transfer electrons across their membrane(s) to/from solid-phase materials – has implications for a wide range of biogeochemically important processes in marine environments. Though EET is thought to play an important role in the oxidation of inorganic minerals by lithotrophic organisms, the mechanisms involved in the oxidation of solid particles are poorly understood. To explore the genetic basis of oxidative EET, we utilized genomic analyses and transposon insertion mutagenesis screens (Tn-seq) in the metabolically flexible, lithotrophic Alphaproteobacterium Thioclava electrotropha ElOx9T. The finished genome of this strain is 4.3 MB, and consists of 4,139 predicted ORFs, 54 contain heme binding motifs, and 33 of those 54 are predicted to localize to the cell envelope or have unknown localizations. To begin to understand the genetic basis of oxidative EET in ElOx9T, we constructed a transposon mutant library in semi-rich media which was comprised of >91,000 individual mutants encompassing >69,000 unique TA dinucleotide insertion sites. The library was subjected to heterotrophic growth on minimal media with acetate and autotrophic oxidative EET conditions on indium tin oxide coated glass electrodes poised at –278 mV vs. SHE or un-poised in an open circuit condition. We identified 528 genes classified as essential under these growth conditions. With respect to electrochemical conditions, 25 genes were essential under oxidative EET conditions, and 29 genes were essential in both the open circuit control and oxidative EET conditions. Though many of the genes identified under electrochemical conditions are predicted to be localized in the cytoplasm and lack heme binding motifs and/or homology to known EET proteins, we identified several hypothetical proteins and poorly characterized oxidoreductases that implicate a novel mechanism(s) for EET that warrants further study. Our results provide a starting point to explore the genetic basis of novel oxidative EET in this marine sediment microbe.
Collapse
Affiliation(s)
- Joshua D Sackett
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH, United States
| | - Nitin Kamble
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH, United States
| | - Edmund Leach
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH, United States
| | - Taruna Schuelke
- Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, Santa Barbara, CA, United States
| | - Elizabeth Wilbanks
- Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, Santa Barbara, CA, United States
| | - Annette R Rowe
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH, United States
| |
Collapse
|
8
|
Davenport EJ, Bose A. Taxonomic Re-Evaluation and Genomic Comparison of Novel Extracellular Electron Uptake-Capable Rhodovulum visakhapatnamense and Rhodovulum sulfidophilum Isolates. Microorganisms 2022; 10:1235. [PMID: 35744753 PMCID: PMC9230146 DOI: 10.3390/microorganisms10061235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 06/14/2022] [Accepted: 06/15/2022] [Indexed: 11/28/2022] Open
Abstract
Rhodovulum spp. are anoxygenic phototrophic purple bacteria with versatile metabolisms, including the ability to obtain electrons from minerals in their environment to drive photosynthesis, a relatively novel process called phototrophic extracellular electron uptake (pEEU). A total of 15 strains of Rhodovulum sulfidophilum were isolated from a marine estuary to observe these metabolisms in marine phototrophs. One representative strain, Rhodovulum sulfidophilum strain AB26, can perform phototrophic iron oxidation (photoferrotrophy) and couples carbon dioxide fixation to pEEU. Here, we reclassify two R. sulfidophilum isolates, strainAB26 and strain AB19, as Rhodovulum visakhapatnamense using taxonomic re-evaluation based on 16S and pufM phylogenetic analyses. The strain AB26 genome consists of 4,380,746 base-pairs, including two plasmids, and encodes 4296 predicted protein-coding genes. Strain AB26 contains 22 histidine kinases, 20 response regulators, and dedicates ~16% of its genome to transport. Transcriptomic data under aerobic, photoheterotrophy, photoautotrophy, and pEEU reveals how gene expression varies between metabolisms in a novel R. visakhapatnamense strain. Genome comparison led by transcriptomic data under pEEU reveals potential pEEU-relevant genes both unique to R. visakhapatnamense strains and shared within the R. sulfidophilum genomes. With these data we identify potential pEEU-important transcripts and how speciation may affect molecular mechanisms of pEEU in Rhodovulum species from the same environment.
Collapse
Affiliation(s)
| | - Arpita Bose
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130, USA;
| |
Collapse
|
9
|
Gupta D, Shalvarjian KE, Nayak DD. An archaea-specific c-type cytochrome maturation machinery is crucial for methanogenesis in Methanosarcina acetivorans. eLife 2022; 11:76970. [PMID: 35380107 PMCID: PMC9084895 DOI: 10.7554/elife.76970] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 04/04/2022] [Indexed: 11/13/2022] Open
Abstract
c-Type cytochromes (cyt c) are proteins that undergo post-translational modification to covalently bind heme, which allows them to facilitate redox reactions in electron transport chains across all domains of life. Genomic evidence suggests that cyt c are involved in electron transfer processes among the Archaea, especially in members that produce or consume the potent greenhouse gas methane. However, neither the maturation machinery for cyt c in Archaea nor their role in methane metabolism has ever been functionally characterized. Here, we have used CRISPR-Cas9 genome editing tools to map a distinct pathway for cyt c biogenesis in the model methanogenic archaeon Methanosarcina acetivorans, and have also identified substrate-specific functional roles for cyt c during methanogenesis. Although the cyt c maturation machinery from M. acetivorans is universally conserved in the Archaea, our evolutionary analyses indicate that different clades of Archaea acquired this machinery through multiple independent horizontal gene transfer events from different groups of Bacteria. Overall, we demonstrate the convergent evolution of a novel Archaea-specific cyt c maturation machinery and its physiological role during methanogenesis, a process which contributes substantially to global methane emissions. Archaea are single-celled organisms that were discovered over half a century ago. Recently, there has been a renewed interest in these microbes because theyplay a key role in climate change by controlling greenhouse gas emissions, like methane. Indeed, methane-producing Archaea generate nearly 70% of the methane gas released into the atmosphere. A group of proteins called c-type cytochromes are essential to energy generation in several methane-producing archaea. However, it is a mystery how Archaea assemble their c-type cytochromes. In fact, genomic studies suggest that Archaea are missing some of the c-type cytochrome assembly machinery that bacteria use. This has led scientists to suspect that Archaea have an alternate mechanism for building these essential components. To solve this mystery, Gupta, Shalvarjian, and Nayak used CRISPR-Cas9 gene-editing tools to characterize which proteins are essential for c-type cytochrome production in Methanosarcina acetivorans, a species of Archaea that produces methane. These experiments showed that M. acetivorans discarded a few parts of the process used by bacteria to generate c-type cytochromes, streamlining the assembly of these proteins. By comparing the genes of different Archaeal species, Gupta, Shalvarjian and Nayak were able to determine that Archaea acquired the genes for producing c-type cytochromes from bacteria via horizontal gene transfer, a process in which genes move directly from one organism into another. The streamlining of the process took place later, as different Archaeal species evolved independently, but losing the same parts of the process. Gupta Shalvajiran and Nayak’s experiments also showed that c-type cytochromes are essential for the growth and fitness of methane-producing Archaea like M. acetivorans. The role of c-type cytochromes in methane production varies in different species of Archaea depending on their growth substrate or where they live. These results provide vital information about how Archaea produce methane, and the tools and techniques developed will aid further investigation of the role of Archaea in climate change.
Collapse
Affiliation(s)
- Dinesh Gupta
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Katie E Shalvarjian
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Dipti D Nayak
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| |
Collapse
|
10
|
Conners EM, Rengasamy K, Bose A. "Electroactive biofilms: how microbial electron transfer enables bioelectrochemical applications". J Ind Microbiol Biotechnol 2022; 49:6563884. [PMID: 35381088 PMCID: PMC9338886 DOI: 10.1093/jimb/kuac012] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 03/30/2022] [Indexed: 11/22/2022]
Abstract
Microbial biofilms are ubiquitous. In marine and freshwater ecosystems, microbe–mineral interactions sustain biogeochemical cycles, while biofilms found on plants and animals can range from pathogens to commensals. Moreover, biofouling and biocorrosion represent significant challenges to industry. Bioprocessing is an opportunity to take advantage of biofilms and harness their utility as a chassis for biocommodity production. Electrochemical bioreactors have numerous potential applications, including wastewater treatment and commodity production. The literature examining these applications has demonstrated that the cell–surface interface is vital to facilitating these processes. Therefore, it is necessary to understand the state of knowledge regarding biofilms’ role in bioprocessing. This mini-review discusses bacterial biofilm formation, cell–surface redox interactions, and the role of microbial electron transfer in bioprocesses. It also highlights some current goals and challenges with respect to microbe-mediated bioprocessing and future perspectives.
Collapse
Affiliation(s)
- Eric M Conners
- Department of Biology. One Brookings Drive, Washington University in St. Louis, Missouri, 63105, USA
| | - Karthikeyan Rengasamy
- Department of Biology. One Brookings Drive, Washington University in St. Louis, Missouri, 63105, USA
| | - Arpita Bose
- Department of Biology. One Brookings Drive, Washington University in St. Louis, Missouri, 63105, USA
| |
Collapse
|
11
|
Paquete CM, Rosenbaum MA, Bañeras L, Rotaru AE, Puig S. Let's chat: Communication between electroactive microorganisms. BIORESOURCE TECHNOLOGY 2022; 347:126705. [PMID: 35065228 DOI: 10.1016/j.biortech.2022.126705] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Revised: 01/07/2022] [Accepted: 01/08/2022] [Indexed: 06/14/2023]
Abstract
Electroactive microorganisms can exchange electrons with other cells or conductive interfaces in their extracellular environment. This property opens the way to a broad range of practical biotechnological applications, from manufacturing sustainable chemicals via electrosynthesis, to bioenergy, bioelectronics or improved, low-energy demanding wastewater treatments. Besides, electroactive microorganisms play key roles in environmental bioremediation, significantly impacting process efficiencies. This review highlights our present knowledge on microbial interactions promoting the communication between electroactive microorganisms in a biofilm on an electrode in bioelectrochemical systems (BES). Furthermore, the immediate knowledge gaps that must be closed to develop novel technologies will also be acknowledged.
Collapse
Affiliation(s)
- Catarina M Paquete
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-156 Oeiras, Portugal
| | - Miriam A Rosenbaum
- Bio Pilot Plant, Leibniz Institute for Natural Product Research and Infection Biology - Hans-Knöll-Institute, Beutenbergstrasse 11a, Jena, Germany; Faculty of Biological Sciences, Friedrich Schiller University, Jena, Germany
| | - Lluís Bañeras
- Group of Molecular Microbial Ecology, Institute of Aquatic Ecology, University of Girona, C/ Maria Aurèlia Capmany, 40, E-17003 Girona, Spain
| | - Amelia-Elena Rotaru
- Faculty of Natural Sciences, Department of Biology, University of Southern Denmark, Odense, Denmark
| | - Sebastià Puig
- LEQUiA, Institute of the Environment, University of Girona, Carrer Maria Aurelia Capmany, 69, E-17003 Girona, Spain.
| |
Collapse
|
12
|
Chaudhary S, Yadav S, Singh R, Sadhotra C, Patil SA. Extremophilic electroactive microorganisms: Promising biocatalysts for bioprocessing applications. BIORESOURCE TECHNOLOGY 2022; 347:126663. [PMID: 35017088 DOI: 10.1016/j.biortech.2021.126663] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2021] [Revised: 12/28/2021] [Accepted: 12/29/2021] [Indexed: 06/14/2023]
Abstract
Electroactive microorganisms (EAMs) use extracellular electron transfer (EET) processes to access insoluble electron donors or acceptors in cellular respiration. These are used in developing microbial electrochemical technologies (METs) for biosensing and bioelectronics applications and the valorization of liquid and gaseous wastes. EAMs from extreme environments can be useful to overcome the existing limitations of METs operated with non-extreme microorganisms. Studying extreme EAMs is also necessary to improve understanding of respiratory processes involving EET. This article first discusses the advantages of using extreme EAMs in METs and summarizes the diversity of EAMs from different extreme environments. It is followed by a detailed discussion on their use as biocatalysts in various bioprocessing applications via bioelectrochemical systems. Finally, the challenges associated with operating METs under extreme conditions and promising research opportunities on fundamental and applied aspects of extreme EAMs are presented.
Collapse
Affiliation(s)
- Srishti Chaudhary
- Department of Earth and Environmental Sciences, Indian Institute of Science Education and Research Mohali (IISER Mohali), Sector 81, S.A.S. Nagar, Manauli PO 140306, Punjab, India
| | - Sukrampal Yadav
- Department of Earth and Environmental Sciences, Indian Institute of Science Education and Research Mohali (IISER Mohali), Sector 81, S.A.S. Nagar, Manauli PO 140306, Punjab, India
| | - Ramandeep Singh
- Department of Earth and Environmental Sciences, Indian Institute of Science Education and Research Mohali (IISER Mohali), Sector 81, S.A.S. Nagar, Manauli PO 140306, Punjab, India
| | - Chetan Sadhotra
- Department of Earth and Environmental Sciences, Indian Institute of Science Education and Research Mohali (IISER Mohali), Sector 81, S.A.S. Nagar, Manauli PO 140306, Punjab, India
| | - Sunil A Patil
- Department of Earth and Environmental Sciences, Indian Institute of Science Education and Research Mohali (IISER Mohali), Sector 81, S.A.S. Nagar, Manauli PO 140306, Punjab, India.
| |
Collapse
|
13
|
Lovley DR. Electrotrophy: Other microbial species, iron, and electrodes as electron donors for microbial respirations. BIORESOURCE TECHNOLOGY 2022; 345:126553. [PMID: 34906705 DOI: 10.1016/j.biortech.2021.126553] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 12/06/2021] [Accepted: 12/08/2021] [Indexed: 06/14/2023]
Abstract
Electrotrophy, the growth of microbes on extracellular electron donors, drives important biogeochemical cycles and has practical applications. Studies of Fe(II)-based electrotrophy have provided foundational cytochrome-based mechanistic models for electron transport into cells. Direct electron uptake from other microbial species, Fe(0), or cathodes is of intense interest due to its potential roles in the production and anaerobic oxidation of methane, corrosion, and bioelectrochemical technologies. Other cells or Fe(0) can serve as the sole electron donor supporting the growth of several Geobacter and methanogen strains that are unable to use H2 as an electron donor, providing strong evidence for electrotrophy. Additional evidence for electrotrophy in Geobacter strains and Methanosarcina acetivorans is a requirement for outer-surface c-type cytochromes. However, in most instances claims for electrotrophy in anaerobes are based on indirect inference and the possibility that H2 is actually the electron donor supporting growth has not been rigorously excluded.
Collapse
Affiliation(s)
- Derek R Lovley
- Electrobiomaterials Institute, Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang 110819, China; Department of Microbiology and Institute for Applied Life Sciences (IALS), University of Massachusetts, Amherst, MA, USA.
| |
Collapse
|
14
|
Abel AJ, Hilzinger JM, Arkin AP, Clark DS. Systems-informed genome mining for electroautotrophic microbial production. Bioelectrochemistry 2022; 145:108054. [DOI: 10.1016/j.bioelechem.2022.108054] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 12/15/2021] [Accepted: 01/06/2022] [Indexed: 01/09/2023]
|
15
|
Liang D, Liu X, Woodard TL, Holmes DE, Smith JA, Nevin KP, Feng Y, Lovley DR. Extracellular Electron Exchange Capabilities of Desulfovibrio ferrophilus and Desulfopila corrodens. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:16195-16203. [PMID: 34748326 DOI: 10.1021/acs.est.1c04071] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Microbial extracellular electron transfer plays an important role in diverse biogeochemical cycles, metal corrosion, bioelectrochemical technologies, and anaerobic digestion. Evaluation of electron uptake from pure Fe(0) and stainless steel indicated that, in contrast to previous speculation in the literature, Desulfovibrio ferrophilus and Desulfopila corrodens are not able to directly extract electrons from solid-phase electron-donating surfaces. D. ferrophilus grew with Fe(III) as the electron acceptor, but Dp. corrodens did not. D. ferrophilus reduced Fe(III) oxide occluded within porous alginate beads, suggesting that it released a soluble electron shuttle to promote Fe(III) oxide reduction. Conductive atomic force microscopy revealed that the D. ferrophilus pili are electrically conductive and the expression of a gene encoding an aromatics-rich putative pilin was upregulated during growth on Fe(III) oxide. The expression of genes for multi-heme c-type cytochromes was not upregulated during growth with Fe(III) as the electron acceptor, and genes for a porin-cytochrome conduit across the outer membrane were not apparent in the genome. The results suggest that D. ferrophilus has adopted a novel combination of strategies to enable extracellular electron transport, which may be of biogeochemical and technological significance.
Collapse
Affiliation(s)
- Dandan Liang
- Department of Microbiology, University of Massachusetts, Amherst, Massachusetts 01003, United States
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, P. R. China
| | - Xinying Liu
- Department of Microbiology, University of Massachusetts, Amherst, Massachusetts 01003, United States
- College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China
| | - Trevor L Woodard
- Department of Microbiology, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Dawn E Holmes
- Department of Microbiology, University of Massachusetts, Amherst, Massachusetts 01003, United States
- Department of Physical and Biological Sciences, Western New England University, Springfield, Massachusetts 01119-2612, United States
| | - Jessica A Smith
- Department of Microbiology, University of Massachusetts, Amherst, Massachusetts 01003, United States
- Department of Biomolecular Sciences, Central Connecticut State University, New Britain, Connecticut 06053-2490, United States
| | - Kelly P Nevin
- Department of Microbiology, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Yujie Feng
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, P. R. China
| | - Derek R Lovley
- Department of Microbiology, University of Massachusetts, Amherst, Massachusetts 01003, United States
| |
Collapse
|
16
|
Complete Genome Sequence of Halomonas sp. Strain FeN2, a Novel Cathode-Oxidizing Bacterium Isolated from Catalina Harbor Sediments. Microbiol Resour Announc 2021; 10:e0086221. [PMID: 34792381 PMCID: PMC8601139 DOI: 10.1128/mra.00862-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We report the complete, closed, circular genome of Halomonas sp. strain FeN2, a metabolically versatile electrotroph that was isolated from Catalina Harbor sediments. The 4.8-Mb genome contains 4,286 protein-coding genes and has complete glycolytic, tricarboxylic acid, glyoxylate, pentose phosphate, and reductive pentose phosphate pathways. FeN2 also contains genes for aerobic and anaerobic (denitrification) respiration.
Collapse
|
17
|
Photoferrotrophy and phototrophic extracellular electron uptake is common in the marine anoxygenic phototroph Rhodovulum sulfidophilum. THE ISME JOURNAL 2021; 15:3384-3398. [PMID: 34054125 PMCID: PMC8528915 DOI: 10.1038/s41396-021-01015-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 05/07/2021] [Accepted: 05/12/2021] [Indexed: 02/03/2023]
Abstract
Photoferrotrophy allows anoxygenic phototrophs to use reduced iron as an electron donor for primary productivity. Recent work shows that freshwater photoferrotrophs can use electrons from solid-phase conductive substances via phototrophic extracellular electron uptake (pEEU), and the two processes share the underlying electron uptake mechanism. However, the ability of marine phototrophs to perform photoferrotrophy and pEEU, and the contribution of these processes to primary productivity is largely unknown. To fill this knowledge gap, we isolated 15 new strains of the marine anoxygenic phototroph Rhodovulum sulfidophilum on electron donors such as acetate and thiosulfate. We observed that all of the R. sulfidophilum strains isolated can perform photoferrotrophy. We chose strain AB26 as a representative strain to study further, and find that it can also perform pEEU from poised electrodes. We show that during pEEU, AB26 transfers electrons to the photosynthetic electron transport chain. Furthermore, systems biology-guided mutant analysis shows that R. sulfidophilum AB26 uses a previously unknown diheme cytochrome c protein, which we call EeuP, for pEEU but not photoferrotrophy. Homologs of EeuP occur in a range of widely distributed marine microbes. Overall, these results suggest that photoferrotrophy and pEEU contribute to the biogeochemical cycling of iron and carbon in marine ecosystems.
Collapse
|
18
|
Dong F, Lee YS, Gaffney EM, Liou W, Minteer SD. Engineering Cyanobacterium with Transmembrane Electron Transfer Ability for Bioelectrochemical Nitrogen Fixation. ACS Catal 2021. [DOI: 10.1021/acscatal.1c03038] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Fangyuan Dong
- Department of Chemistry, University of Utah, 315 South 1400 East, RM 2020, Salt Lake City, Utah 84112, United States
| | - Yoo Seok Lee
- Department of Chemistry, University of Utah, 315 South 1400 East, RM 2020, Salt Lake City, Utah 84112, United States
| | - Erin M. Gaffney
- Department of Chemistry, University of Utah, 315 South 1400 East, RM 2020, Salt Lake City, Utah 84112, United States
| | - Willisa Liou
- Department of Chemistry, University of Utah, 315 South 1400 East, RM 2020, Salt Lake City, Utah 84112, United States
| | - Shelley D. Minteer
- Department of Chemistry, University of Utah, 315 South 1400 East, RM 2020, Salt Lake City, Utah 84112, United States
| |
Collapse
|
19
|
Tong T, Chen X, Hu G, Wang XL, Liu GQ, Liu L. Engineering microbial metabolic energy homeostasis for improved bioproduction. Biotechnol Adv 2021; 53:107841. [PMID: 34610353 DOI: 10.1016/j.biotechadv.2021.107841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 08/25/2021] [Accepted: 09/28/2021] [Indexed: 10/20/2022]
Abstract
Metabolic energy (ME) homeostasis is essential for the survival and proper functioning of microbial cell factories. However, it is often disrupted during bioproduction because of inefficient ME supply and excessive ME consumption. In this review, we propose strategies, including reinforcement of the capacity of ME-harvesting systems in autotrophic microorganisms; enhancement of the efficiency of ME-supplying pathways in heterotrophic microorganisms; and reduction of unessential ME consumption by microbial cells, to address these issues. This review highlights the potential of biotechnology in the engineering of microbial ME homeostasis and provides guidance for the higher efficient bioproduction of microbial cell factories.
Collapse
Affiliation(s)
- Tian Tong
- Hunan Provincial Key Laboratory for Forestry Biotechnology, Central South University of Forestry and Technology, Changsha 410004, China; International Cooperation Base of Science and Technology Innovation on Forest Resource Biotechnology of Hunan Province, Central South University of Forestry and Technology, Changsha 410004, China
| | - Xiulai Chen
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China; International Joint Laboratory on Food Safety, Jiangnan University, Wuxi 214122, China
| | - Guipeng Hu
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China; International Joint Laboratory on Food Safety, Jiangnan University, Wuxi 214122, China
| | - Xiao-Ling Wang
- Hunan Provincial Key Laboratory for Forestry Biotechnology, Central South University of Forestry and Technology, Changsha 410004, China; International Cooperation Base of Science and Technology Innovation on Forest Resource Biotechnology of Hunan Province, Central South University of Forestry and Technology, Changsha 410004, China
| | - Gao-Qiang Liu
- Hunan Provincial Key Laboratory for Forestry Biotechnology, Central South University of Forestry and Technology, Changsha 410004, China; International Cooperation Base of Science and Technology Innovation on Forest Resource Biotechnology of Hunan Province, Central South University of Forestry and Technology, Changsha 410004, China.
| | - Liming Liu
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China; International Joint Laboratory on Food Safety, Jiangnan University, Wuxi 214122, China.
| |
Collapse
|
20
|
Lovley DR, Holmes DE. Electromicrobiology: the ecophysiology of phylogenetically diverse electroactive microorganisms. Nat Rev Microbiol 2021; 20:5-19. [PMID: 34316046 DOI: 10.1038/s41579-021-00597-6] [Citation(s) in RCA: 160] [Impact Index Per Article: 53.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/16/2021] [Indexed: 02/03/2023]
Abstract
Electroactive microorganisms markedly affect many environments in which they establish outer-surface electrical contacts with other cells and minerals or reduce soluble extracellular redox-active molecules such as flavins and humic substances. A growing body of research emphasizes their broad phylogenetic diversity and shows that these microorganisms have key roles in multiple biogeochemical cycles, as well as the microbiome of the gut, anaerobic waste digesters and metal corrosion. Diverse bacteria and archaea have independently evolved cytochrome-based strategies for electron exchange between the outer cell surface and the cell interior, but cytochrome-free mechanisms are also prevalent. Electrically conductive protein filaments, soluble electron shuttles and non-biological conductive materials can substantially extend the electronic reach of microorganisms beyond the surface of the cell. The growing appreciation of the diversity of electroactive microorganisms and their unique electronic capabilities is leading to a broad range of applications.
Collapse
Affiliation(s)
- Derek R Lovley
- Electrobiomaterials Institute, Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang, China. .,Department of Microbiology, University of Massachusetts, Amherst, MA, USA. .,Institute for Applied Life Sciences (IALS), University of Massachusetts, Amherst, MA, USA.
| | - Dawn E Holmes
- Department of Microbiology, University of Massachusetts, Amherst, MA, USA.,Institute for Applied Life Sciences (IALS), University of Massachusetts, Amherst, MA, USA.,Department of Physical and Biological Sciences, Western New England University, Springfield, MA, USA
| |
Collapse
|
21
|
Evidence for Horizontal and Vertical Transmission of Mtr-Mediated Extracellular Electron Transfer among the Bacteria. mBio 2021; 13:e0290421. [PMID: 35100867 PMCID: PMC8805035 DOI: 10.1128/mbio.02904-21] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Some bacteria and archaea have evolved the means to use extracellular electron donors and acceptors for energy metabolism, a phenomenon broadly known as extracellular electron transfer (EET). One such EET mechanism is the transmembrane electron conduit MtrCAB, which has been shown to transfer electrons derived from metabolic substrates to electron acceptors, like Fe(III) and Mn(IV) oxides, outside the cell. Although most studies of MtrCAB-mediated EET have been conducted in Shewanella oneidensis MR-1, recent investigations in Vibrio and Aeromonas species have revealed that the electron-donating proteins that support MtrCAB in Shewanella are not as representative as previously thought. This begs the question of how widespread the capacity for MtrCAB-mediated EET is, the changes it has accrued in different lineages, and where these lineages persist today. Here, we employed a phylogenetic and comparative genomics approach to identify the MtrCAB system across all domains of life. We found mtrCAB in the genomes of numerous diverse Bacteria from a wide range of environments, and the patterns therein strongly suggest that mtrCAB was distributed through both horizontal and subsequent vertical transmission, and with some cases indicating downstream modular diversification of both its core and accessory components. Our data point to an emerging evolutionary story about metal-oxidizing and -reducing metabolism, demonstrates that this capacity for EET has broad relevance to a diversity of taxa and the biogeochemical cycles they drive, and lays the foundation for further studies to shed light on how this mechanism may have coevolved with Earth's redox landscape. IMPORTANCE While many metabolisms make use of soluble, cell-permeable substrates like oxygen or hydrogen, there are other substrates, like iron or manganese, that cannot be brought into the cell. Some bacteria and archaea have evolved the means to directly "plug in" to such environmental electron reservoirs in a process known as extracellular electron transfer (EET), making them powerful agents of biogeochemical change and promising vehicles for bioremediation and alternative energy. Yet the diversity, distribution, and evolution of EET mechanisms are poorly constrained. Here, we present findings showing that the genes encoding one such EET system (mtrCAB) are present in a broad diversity of bacteria found in a wide range of environments, emphasizing the ubiquity and potential impact of EET in our biosphere. Our results suggest that these genes have been disseminated largely through horizontal transfer, and the changes they have accrued in these lineages potentially reflect adaptations to changing environments.
Collapse
|
22
|
Rotaru AE, Yee MO, Musat F. Microbes trading electricity in consortia of environmental and biotechnological significance. Curr Opin Biotechnol 2021; 67:119-129. [PMID: 33540362 DOI: 10.1016/j.copbio.2021.01.014] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 01/15/2021] [Accepted: 01/19/2021] [Indexed: 02/08/2023]
Abstract
Favorable interspecies associations prevail in natural microbial assemblages. Some of these favorable associations are co-metabolic dependent partnerships in which extracellular electrons are exchanged between species. For such electron exchange to occur, the cells must exhibit electroactive interfaces and get involved in direct cell-to-cell contact (Direct Interspecies Electron Transfer/DIET) or use available conductive mineral grains from their environment (Conductive-particle-mediated Interspecies Electron Transfer/CIET). This review will highlight recent discoveries and knowledge gaps regarding DIET and CIET interspecies associations in artificial co-cultures and consortia from natural and man-made environments and emphasize approaches to validate DIET and CIET. Additionally, we acknowledge the initiation of a movement towards applying electric syntrophies in biotechnology, bioremediation and geoengineering for natural attenuation of toxic compounds. Next, we have highlighted the urgent research needs that must be met to develop such technologies.
Collapse
Affiliation(s)
| | - Mon Oo Yee
- Lawrence Berkley National Laboratories, Cyclotron Rd. 1, Berkeley, CA, United States
| | - Florin Musat
- Helmholtz Center for Environmental Research, Permoserstraße 15, Leipzig, Germany
| |
Collapse
|
23
|
Baltz RH, Kao K, Link AJ, Marsili E, Reguera G, Shao Z, Vandamme EJ, Jeffries TW, Gonzalez R. Introduction to Special Issue on "Frontiers in Industrial Microbiology and Biotechnology 2020". J Ind Microbiol Biotechnol 2020; 47:621-622. [PMID: 33123834 DOI: 10.1007/s10295-020-02322-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
| | - Katy Kao
- Department of Chemical and Materials Engineering, San Jose State University, San Jose, CA, USA
| | - A James Link
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ, USA
| | - Enrico Marsili
- Department of Chemical and Materials Engineering, Nazarbayev University, Nur-Sultan, Kazakhstan
| | - Gemma Reguera
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA
| | - Zengyi Shao
- Department of Chemical and Biological Engineering, Iowa State University, Ames, IA, USA
| | | | | | - Ramon Gonzalez
- Department of Chemical and Biomedical Engineering, University of South Florida, Tampa, FL, USA.
| |
Collapse
|