1
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Yan X, Su H, Liao C, Zhao Q, Qian X, Tian L, Li N, Wang X. Metabolic allocation strategies of Geobacter in electroactive biofilms to adapt to varying acetate supply concentrations. WATER RESEARCH 2025; 283:123890. [PMID: 40424924 DOI: 10.1016/j.watres.2025.123890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2025] [Revised: 05/21/2025] [Accepted: 05/22/2025] [Indexed: 05/29/2025]
Abstract
Geobacter species play a key role in acetate-fed electroactive biofilms (EABs), but their competitiveness varies with acetate supply concentration for unclear reasons. By continuously supplying different concentrations of acetate, we discovered an adaptive metabolic strategy of Geobacter biofilms, centered on regulating carbon allocation to protein synthesis, polysaccharide production, and the TCA cycle. Growth and reproduction were prioritized in response to acetate limitation under low supply concentrations, whereas catabolic efficiency was enhanced when acetate was sufficient. Excess acetate also induced the toxic effects of intracellular acetyl-CoA accumulation, triggering metabolic processes including stress responses, acetyl-CoA hydrolase synthesis, and carbon source storage. These metabolic adaptations ultimately determined the competitive niche of Geobacter in wastewater EABs, allowing for population dominance under acetate limitation and enhancing current production when acetate was abundant. Our findings give new insights into Geobacter's survival strategies in various environments with different acetate availability, and provide a theoretical basis for targeted regulation of the performance and stability of EABs to achieve environmental functions.
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Affiliation(s)
- Xuejun Yan
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, Academy for Advanced Interdisciplinary Studies, College of Environmental Science & Engineering, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, PR China; College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, PR China
| | - Huijuan Su
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, Academy for Advanced Interdisciplinary Studies, College of Environmental Science & Engineering, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, PR China
| | - Chengmei Liao
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, Academy for Advanced Interdisciplinary Studies, College of Environmental Science & Engineering, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, PR China
| | - Qian Zhao
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, Academy for Advanced Interdisciplinary Studies, College of Environmental Science & Engineering, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, PR China
| | - Xun Qian
- College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, PR China
| | - Lili Tian
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, Academy for Advanced Interdisciplinary Studies, College of Environmental Science & Engineering, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, PR China
| | - Nan Li
- School of Environmental Science and Engineering, Tianjin University, No. 92 Weijin Road, Nankai District, Tianjin 300072, PR China
| | - Xin Wang
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, Academy for Advanced Interdisciplinary Studies, College of Environmental Science & Engineering, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, PR China.
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2
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Wang H, Li C, Wang Y, Zhang H. Bacterial Species in Engineered Living Materials: Strategies and Future Directions. Microb Biotechnol 2025; 18:e70164. [PMID: 40407296 PMCID: PMC12100766 DOI: 10.1111/1751-7915.70164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2024] [Revised: 04/28/2025] [Accepted: 05/08/2025] [Indexed: 05/26/2025] Open
Abstract
In recent years, there has been a notable increase interest in engineered living materials (ELMs) owing to their considerable potential. One key area of research within this field is the utilisation of various species of bacteria to create innovative living materials. In order to accelerate the advancement of bacterial-based living materials, a systematic summary of bacterial species and their design strategies is essential. Yet, up to this point, no applicable reviews have been documented. This review offers a concise introduction to living materials derived from bacteria, delves into the strategies and applications of each bacterial species in this realm, and provides perspectives and future outlooks in this field.
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Affiliation(s)
- Hu Wang
- School of Statistics and Applied MathematicsAnhui University of Finance and EconomicsBengbuAnhuiChina
| | - Chunzhong Li
- School of Statistics and Applied MathematicsAnhui University of Finance and EconomicsBengbuAnhuiChina
| | - Yanmin Wang
- School of Statistics and Applied MathematicsAnhui University of Finance and EconomicsBengbuAnhuiChina
| | - Huanming Zhang
- School of Statistics and Applied MathematicsAnhui University of Finance and EconomicsBengbuAnhuiChina
- School of Mathematics and StatisticsHuaibei Normal UniversityHuaibeiAnhuiChina
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3
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Tabares M, Kashefi K, Reguera G. Adaptive responses of Trichlorobacter lovleyi to nitrite detoxification reveal overlooked contributions of Geobacterales to nitrate ammonification. THE ISME JOURNAL 2025; 19:wraf054. [PMID: 40101204 PMCID: PMC11972089 DOI: 10.1093/ismejo/wraf054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/01/2024] [Revised: 01/20/2025] [Accepted: 03/17/2025] [Indexed: 03/20/2025]
Abstract
Poorly understood microorganisms "short-circuit" the nitrogen cycle via the dissimilatory nitrate reduction to ammonium to retain the element in agricultural lands and stimulate crop productivity. The prevalence of Geobacterales closely related to Trichlorobacter lovleyi in nitrate ammonification hotspots motivated us to investigate adaptive responses contributing to ammonification rates in the laboratory type strain T. lovleyi SZ. Here, we describe the identification of tightly regulated pathways for efficient nitrate foraging and respiration with acetate, an important intermediate of organic matter degradation that Geobacterales efficiently assimilate and oxidize. Challenging the established dogma that high carbon/nitrate ratios stimulate the reduction of nitrate to ammonium, T. lovleyi doubled rapidly across a wide range of ratios provided nitrate concentrations were low enough to prevent the accumulation of the toxic nitrite intermediate. Yet, excess electrons during hydrogenotrophic growth alleviated nitrite toxicity and stimulated the reduction of nitrate to ammonium even under conditions of severe acetate limitation. These findings underscore the importance of nitrite toxicity in the ammonification of nitrate by Geobacterales and provide much needed mechanistic understanding of microbial adaptations contributing to soil nitrogen conservation. This information is critical to enhance the predictive value of genomic-based traits in environmental surveys and to guide strategies for sustainable management of nitrogen fertilization as well as mitigation of green-house emissions and agrochemical leaching from agricultural lands.
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Affiliation(s)
- Marcela Tabares
- Department of Microbiology, Genetics & Immunology, Michigan State University, East Lansing, MI 48824, United States
| | - Kazem Kashefi
- Department of Microbiology, Genetics & Immunology, Michigan State University, East Lansing, MI 48824, United States
| | - Gemma Reguera
- Department of Microbiology, Genetics & Immunology, Michigan State University, East Lansing, MI 48824, United States
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4
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Beretta G, Sangalli M, Sezenna E, Tofalos AE, Franzetti A, Saponaro S. Microbial electrochemical Cr(VI) reduction in a soil continuous flow system. INTEGRATED ENVIRONMENTAL ASSESSMENT AND MANAGEMENT 2024; 20:2033-2049. [PMID: 38953765 DOI: 10.1002/ieam.4972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 05/21/2024] [Accepted: 05/28/2024] [Indexed: 07/04/2024]
Abstract
Microbial electrochemical technologies represent innovative approaches to contaminated soil and groundwater remediation and provide a flexible framework for removing organic and inorganic contaminants by integrating electrochemical and biological techniques. To simulate in situ microbial electrochemical treatment of groundwater plumes, this study investigates Cr(VI) reduction within a bioelectrochemical continuous flow (BECF) system equipped with soil-buried electrodes, comparing it to abiotic and open-circuit controls. Continuous-flow systems were tested with two chromium-contaminated solutions (20-50 mg Cr(VI)/L). Additional nutrients, buffers, or organic substrates were introduced during the tests in the systems. With an initial Cr(VI) concentration of 20 mg/L, 1.00 mg Cr(VI)/(L day) bioelectrochemical removal rate in the BECF system was observed, corresponding to 99.5% removal within nine days. At the end of the test with 50 mg Cr(VI)/L (156 days), the residual Cr(VI) dissolved concentration was two orders of magnitude lower than that in the open circuit control, achieving 99.9% bioelectrochemical removal in the BECF. Bacteria belonging to the orders Solirubrobacteriales, Gaiellales, Bacillales, Gemmatimonadales, and Propionibacteriales characterized the bacterial communities identified in soil samples; differently, Burkholderiales, Mycobacteriales, Cytophagales, Rhizobiales, and Caulobacterales characterized the planktonic bacterial communities. The complexity of the microbial community structure suggests the involvement of different microorganisms and strategies in the bioelectrochemical removal of chromium. In the absence of organic carbon, microbial electrochemical removal of hexavalent chromium was found to be the most efficient way to remove Cr(VI), and it may represent an innovative and sustainable approach for soil and groundwater remediation. Integr Environ Assess Manag 2024;20:2033-2049. © 2024 The Author(s). Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).
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Affiliation(s)
- Gabriele Beretta
- Department of Civil and Environmental Engineering, Politecnico di Milano, Milano, Italy
| | - Michela Sangalli
- Department of Civil and Environmental Engineering, Politecnico di Milano, Milano, Italy
| | - Elena Sezenna
- Department of Civil and Environmental Engineering, Politecnico di Milano, Milano, Italy
| | - Anna Espinoza Tofalos
- Department of Earth and Environmental Sciences, University of Milano-Bicocca, Milano, Italy
- Environmental Research and Innovation (ERIN) Department, Institute of Science and Technology (LIST), Luxembourg, Luxembourg
| | - Andrea Franzetti
- Department of Earth and Environmental Sciences, University of Milano-Bicocca, Milano, Italy
| | - Sabrina Saponaro
- Department of Civil and Environmental Engineering, Politecnico di Milano, Milano, Italy
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5
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Anoy MMI, Hill EA, Garcia MR, Kim WJ, Beliaev AS, Beyenal H. A directional electrode separator improves anodic biofilm current density in a well-mixed single-chamber bioelectrochemical system. Enzyme Microb Technol 2024; 180:110502. [PMID: 39214043 PMCID: PMC11529205 DOI: 10.1016/j.enzmictec.2024.110502] [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: 04/12/2024] [Revised: 08/05/2024] [Accepted: 08/19/2024] [Indexed: 09/04/2024]
Abstract
In this study, a directional electrode separator (DES) was designed and incorporated into a single-chamber bioelectrochemical system (BES) to reduce migration and reoxidation of hydrogen. This issue arises when H2, generated at the cathode, travels to the anode where anodic biofilms use H2. To test the feasibility of our design, a 3D-printed BES reactor equipped with a DES was inoculated with anaerobic digestor granules and operated under fed-batch conditions using fermented corn stover effluent. The DES equipped reactor achieved significantly higher current densities (∼53 A/m²) compared to a conventional single-chamber BES without a separator (∼16 A/m²), showing a 3.3 times improvement. Control abiotic electrochemical experiments revealed that the DES exhibited significantly higher proton conductivity (456±127 µS/mm) compared to a proton exchange membrane (67±21 µS/mm) with a statistical significance of P=0.03. The DES also effectively reduced H2 migration to the anode by 21-fold relative to the control. Overall, incorporating a DES in a single-chamber BES enhanced anodic current density by reducing H2 migration to the anode.
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Affiliation(s)
- Md Monzurul Islam Anoy
- The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA, USA
| | - Eric Allen Hill
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, USA
| | - Marci Ranae Garcia
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, USA
| | - Won-Jun Kim
- The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA, USA
| | - Alexander S Beliaev
- Environmental Molecular Sciences Division, Pacific Northwest National Laboratory, Richland, WA, USA; Centre for Agriculture and the Bioeconomy, Faculty of Science, Queensland University of Technology, Brisbane, QLD 4000, Australia
| | - Haluk Beyenal
- The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA, USA.
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Fang Y, Yang G, Wu X, Lin C, Qin B, Zhuang L. A genetic engineering strategy to enhance outer membrane vesicle-mediated extracellular electron transfer of Geobacter sulfurreducens. Biosens Bioelectron 2024; 250:116068. [PMID: 38280298 DOI: 10.1016/j.bios.2024.116068] [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: 12/02/2023] [Revised: 01/21/2024] [Accepted: 01/22/2024] [Indexed: 01/29/2024]
Abstract
Bioelectrochemical systems (BESs) are unique devices that harness the metabolic activity of electroactive microorganisms (EAMs) to convert chemical energy stored in organic substrates into electrical energy. Enhancing electron transfer efficiency between EAMs and electrodes is the key to practical implementation of BESs. Considering the role of outer membrane vesicles (OMVs) in mediating electron transfer of EAMs, a genetic engineering strategy to achieve OMVs overproduction was explored to enhance electron transfer efficiency and the underlying mechanisms were investigated. This study constructed a mutant strain of Geobacter sulfurreducens that lacked the ompA gene encoding an outer membrane protein. Experimental results showed that the mutant strain produced more OMVs and possessed higher electron transfer efficiency in Fe(III) reduction, dye degradation and current generation in BESs than the wild-type strain. More cargoes such as c-type cytochromes, functional proteins, eDNA, polysaccharides and signaling molecules that might be favorable for electron transfer and biofilm formation were found in OMVs produced by ompA-deficient anodic biofilm, which possibly contributed to the improved electron transfer efficiency of ompA-deficient biofilm. The results indicate that overproduction of OMVs in EAMs might be a potential strategy to enhance BESs performance.
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Affiliation(s)
- Yanlun Fang
- Guangdong Key Laboratory of Environmental Pollution and Health, School of Environment, Jinan University, Guangzhou, 510632, China
| | - Guiqin Yang
- Guangdong Key Laboratory of Environmental Pollution and Health, School of Environment, Jinan University, Guangzhou, 510632, China.
| | - Xian Wu
- Guangdong Key Laboratory of Environmental Pollution and Health, School of Environment, Jinan University, Guangzhou, 510632, China
| | - Canfen Lin
- Guangdong Key Laboratory of Environmental Pollution and Health, School of Environment, Jinan University, Guangzhou, 510632, China
| | - Baoli Qin
- Guangdong Key Laboratory of Environmental Pollution and Health, School of Environment, Jinan University, Guangzhou, 510632, China
| | - Li Zhuang
- Guangdong Key Laboratory of Environmental Pollution and Health, School of Environment, Jinan University, Guangzhou, 510632, China.
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7
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Dzofou Ngoumelah D, Heggeset TMB, Haugen T, Sulheim S, Wentzel A, Harnisch F, Kretzschmar J. Effect of model methanogens on the electrochemical activity, stability, and microbial community structure of Geobacter spp. dominated biofilm anodes. NPJ Biofilms Microbiomes 2024; 10:17. [PMID: 38443373 PMCID: PMC10915144 DOI: 10.1038/s41522-024-00490-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: 03/09/2023] [Accepted: 02/20/2024] [Indexed: 03/07/2024] Open
Abstract
Combining anaerobic digestion (AD) and microbial electrochemical technologies (MET) in AD-MET holds great potential. Methanogens have been identified as one cause of decreased electrochemical activity and deterioration of Geobacter spp. biofilm anodes. A better understanding of the different interactions between methanogenic genera/species and Geobacter spp. biofilms is needed to shed light on the observed reduction in electrochemical activity and stability of Geobacter spp. dominated biofilms as well as observed changes in microbial communities of AD-MET. Here, we have analyzed electrochemical parameters and changes in the microbial community of Geobacter spp. biofilm anodes when exposed to three representative methanogens with different metabolic pathways, i.e., Methanosarcina barkeri, Methanobacterium formicicum, and Methanothrix soehngenii. M. barkeri negatively affected the performance and stability of Geobacter spp. biofilm anodes only in the initial batches. In contrast, M. formicicum did not affect the stability of Geobacter spp. biofilm anodes but caused a decrease in maximum current density of ~37%. M. soehngenii induced a coloration change of Geobacter spp. biofilm anodes and a decrease in the total transferred charge by ~40%. Characterization of biofilm samples after each experiment by 16S rRNA metabarcoding, whole metagenome nanopore sequencing, and shotgun sequencing showed a higher relative abundance of Geobacter spp. after exposure to M. barkeri as opposed to M. formicicum or M. soehngenii, despite the massive biofilm dispersal observed during initial exposure to M. barkeri.
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Affiliation(s)
- Daniel Dzofou Ngoumelah
- DBFZ Deutsches Biomasseforschungszentrum gemeinnützige GmbH (German Biomass Research Centre), Department of Biochemical Conversion, 04347, Leipzig, Germany
| | | | - Tone Haugen
- SINTEF Industry, Department of Biotechnology and Nanomedicine, 7034, Trondheim, Norway
| | - Snorre Sulheim
- SINTEF Industry, Department of Biotechnology and Nanomedicine, 7034, Trondheim, Norway
| | - Alexander Wentzel
- SINTEF Industry, Department of Biotechnology and Nanomedicine, 7034, Trondheim, Norway
| | - Falk Harnisch
- Helmholtz Centre for Environmental Research - UFZ, Department of Microbial Biotechnology, 04318, Leipzig, Germany
| | - Jörg Kretzschmar
- DBFZ Deutsches Biomasseforschungszentrum gemeinnützige GmbH (German Biomass Research Centre), Department of Biochemical Conversion, 04347, Leipzig, Germany.
- Zittau/Görlitz University of Applied Sciences, Faculty of Natural and Environmental Sciences, 02763, Zittau, Germany.
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8
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Jiang Y, Dong Y, Sui M, Yu J, Wu J, Fu D. Towards a new understanding of bioelectrochemical systems from the perspective of microecosystems: A critical review. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 908:168410. [PMID: 37939951 DOI: 10.1016/j.scitotenv.2023.168410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 11/04/2023] [Accepted: 11/05/2023] [Indexed: 11/10/2023]
Abstract
Bioelectrochemical system (BES) holds promise for sustainable energy generation and wastewater treatment. The microbial communities, as the core of BES, play a crucial role in its performance, thus needing to be systematically studied. However, researches considering microbial communities in BES from an ecological perspective are limited. This review provided a comprehensive summary of the BES with special emphasis on microecological principles, commencing with the dynamic formation and succession of the microbial communities. It also clarified the intricate interspecies relationships and quorum-sensing mechanisms regulated by dominant species. Furthermore, this review addressed the crucial themes in BES-related researches on ecological processes, including growth patterns, ecological structures, and defense strategies against external disturbances. By offering this novel perspective, it would contribute to enhancing the understanding of BES-centered technologies and facilitating future research in this field.
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Affiliation(s)
- Yiying Jiang
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes of Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China
| | - Yue Dong
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes of Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China
| | - Mingrui Sui
- College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing 210098, China.
| | - Jimeng Yu
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes of Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China
| | - Jiaxin Wu
- College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing 210098, China
| | - Daxuan Fu
- College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing 210098, China
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9
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Wang H, Zeng S, Luo L, Xu Y, Yasuo I, Luo F. Metatranscriptome revealed how carbon brush addition affected the fermentation of food wastewater in the low-temperature environment. ENVIRONMENTAL RESEARCH 2023; 239:117382. [PMID: 37832774 DOI: 10.1016/j.envres.2023.117382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2023] [Revised: 09/05/2023] [Accepted: 10/10/2023] [Indexed: 10/15/2023]
Abstract
Improving the anaerobic digestion (AD) performance in low-temperature environments has become a key factor in the development of waste treatment and resource recovery in cold regions. The utilization of external carriers to form a biofilm is the simplest and most practical way to enhance the psychrophilic AD performance in cold regions. In this study, the effect of carrier addition on the fermentation performance of low-temperature (15 ± 2 °C) food wastewater was investigated by forming biofilms with carbon brushes. The results showed that although the biofilm formation enhanced methane yields (15.24%), it also caused more accumulation of propionic acid (306.99-626.89 mg/L), and the concentration of acetic acid (86.78-254.71 mg/L) was relatively low. The microbial community revealed the highest abundance of the fermentative bacterium Firmicutes and the carbon brush carrier significantly increased its relative abundance (23.74%). Metatranscriptomic sequencing revealed that the abundance level of Clostridium, Bacteroides, Sedimentibacter and Pelotomaculum was the highest, reaching 80% in all groups. In addition, the abundance level of electroactive microorganisms in biofilms was higher, while the fermentation bacteria and methanogens were lower. This showed that biofilm can enrich more electroactive microorganisms, and granular sludge needs to enrich more fermentation bacteria and methanogens to ensure metabolic activity. Further studies have found that carbon metabolism had the highest activity (27.86%-30.39%) and H+-transporting ATPase (atp) was the most dominant functional enzyme (85.50%-86.65%) involved in electron transport in low-temperature fermentation of food wastewater. Interestingly, these expression levels of active granular sludge were higher than the biofilm formed by carbon brushes. Meanwhile, analysis of the methanogenic pathway found that active granular sludge tends to be directly metabolized to realize acetate to acetyl-CoA by acetyl-CoA synthetase (ACSS), while biofilms were not significantly different in the two metabolic pathways of acetate. These results deepen the understanding of treating low-temperature food wastewater.
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Affiliation(s)
- Hui Wang
- College of Resources and Environment, Southwest University, Chongqing, 400715, China
| | - Shufang Zeng
- College of Resources and Environment, Southwest University, Chongqing, 400715, China
| | - Lijun Luo
- College of Resources and Environment, Southwest University, Chongqing, 400715, China
| | - Yan Xu
- College of Resources and Environment, Southwest University, Chongqing, 400715, China
| | - Igarashi Yasuo
- College of Resources and Environment, Southwest University, Chongqing, 400715, China
| | - Feng Luo
- College of Resources and Environment, Southwest University, Chongqing, 400715, China.
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10
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Rabiço F, Pedrino M, Narcizo JP, de Andrade AR, Reginatto V, Guazzaroni ME. Synthetic Biology Toolkit for a New Species of Pseudomonas Promissory for Electricity Generation in Microbial Fuel Cells. Microorganisms 2023; 11:2044. [PMID: 37630604 PMCID: PMC10458277 DOI: 10.3390/microorganisms11082044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 08/04/2023] [Accepted: 08/07/2023] [Indexed: 08/27/2023] Open
Abstract
Microbial fuel cells (MFCs) offer sustainable solutions for various biotechnological applications and are a crucial area of research in biotechnology. MFCs can effectively treat various refuse, such as wastewater and biodiesel waste by decomposing organic matter and generating electricity. Certain Pseudomonas species possess extracellular electron transfer (EET) pathways, enabling them to transfer electrons from organic compounds to the MFC's anode. Moreover, Pseudomonas species can grow under low-oxygen conditions, which is advantageous considering that the electron transfer process in an MFC typically leads to reduced oxygen levels at the anode. This study focuses on evaluating MFCs inoculated with a new Pseudomonas species grown with 1 g.L-1 glycerol, a common byproduct of biodiesel production. Pseudomonas sp. BJa5 exhibited a maximum power density of 39 mW.m-2. Also, the observed voltammograms and genome analysis indicate the potential production of novel redox mediators by BJa5. Additionally, we investigated the bacterium's potential as a synthetic biology non-model chassis. Through testing various genetic parts, including constitutive promoters, replication origins and cargos using pSEVA vectors as a scaffold, we assessed the bacterium's suitability. Overall, our findings offer valuable insights into utilizing Pseudomonas spp. BJa5 as a novel chassis for MFCs. Synthetic biology approaches can further enhance the performance of this bacterium in MFCs, providing avenues for improvement.
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Affiliation(s)
- Franciene Rabiço
- Department of Biology, Faculty of Philosophy, Sciences and Letters of Ribeirão Preto, University of São Paulo, Ribeirão Preto 14040-901, Brazil; (F.R.); (M.P.)
| | - Matheus Pedrino
- Department of Biology, Faculty of Philosophy, Sciences and Letters of Ribeirão Preto, University of São Paulo, Ribeirão Preto 14040-901, Brazil; (F.R.); (M.P.)
| | - Julia Pereira Narcizo
- Department of Chemistry, Faculty of Philosophy, Sciences and Letters of Ribeirão Preto, University of São Paulo, Ribeirão Preto 14049-900, Brazil; (J.P.N.); (A.R.d.A.); (V.R.)
| | - Adalgisa Rodrigues de Andrade
- Department of Chemistry, Faculty of Philosophy, Sciences and Letters of Ribeirão Preto, University of São Paulo, Ribeirão Preto 14049-900, Brazil; (J.P.N.); (A.R.d.A.); (V.R.)
| | - Valeria Reginatto
- Department of Chemistry, Faculty of Philosophy, Sciences and Letters of Ribeirão Preto, University of São Paulo, Ribeirão Preto 14049-900, Brazil; (J.P.N.); (A.R.d.A.); (V.R.)
| | - María-Eugenia Guazzaroni
- Department of Biology, Faculty of Philosophy, Sciences and Letters of Ribeirão Preto, University of São Paulo, Ribeirão Preto 14040-901, Brazil; (F.R.); (M.P.)
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11
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Dzofou Ngoumelah D, Kuchenbuch A, Harnisch F, Kretzschmar J. Combining Geobacter spp. Dominated Biofilms and Anaerobic Digestion Effluents─The Effect of Effluent Composition and Electrode Potential on Biofilm Activity and Stability. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:2584-2594. [PMID: 36731122 DOI: 10.1021/acs.est.2c07574] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
The combination of anaerobic digestion (AD) and microbial electrochemical technologies (METs) offers different opportunities to increase the efficiency and sustainability of AD processes. However, methanogenic archaea and/or particles may partially hinder combining MET and AD processes. Furthermore, it is unclear if the applied anode potential affects the activity and efficiency of electroactive microorganisms in AD-MET combinations as it is described for more controlled experimental conditions. In this study, we confirm that 6-week-old Geobacter spp. dominated biofilms are by far more active and stable in AD-effluents than 3-week-old Geobacter spp. dominated biofilms. Furthermore, we show that the biofilms are twice as active at -0.2 V compared to 0.4 V, even under challenging conditions occurring in AD-MET systems. Paired-end amplicon sequencing at the DNA level using 16S-rRNA and mcrA gene shows that hydrogenotrophic methanogens incorporate into biofilms immersed in AD-effluent without any negative effect on biofilm stability and electrochemical activity.
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Affiliation(s)
- Daniel Dzofou Ngoumelah
- Department of Biochemical Conversion, DBFZ Deutsches Biomasseforschungszentrum gemeinnützige GmbH (German Biomass Research Centre), Leipzig04347, Saxony, Germany
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research - UFZ, Leipzig04318, Saxony, Germany
| | - Anne Kuchenbuch
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research - UFZ, Leipzig04318, Saxony, Germany
| | - Falk Harnisch
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research - UFZ, Leipzig04318, Saxony, Germany
| | - Jörg Kretzschmar
- Department of Biochemical Conversion, DBFZ Deutsches Biomasseforschungszentrum gemeinnützige GmbH (German Biomass Research Centre), Leipzig04347, Saxony, Germany
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12
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Frühauf‐Wyllie HM, Holtmann D. Geobacter sulfurreducens metabolism at different donor/acceptor ratios. Microbiologyopen 2022; 11:e1322. [PMID: 36314758 PMCID: PMC9494351 DOI: 10.1002/mbo3.1322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2022] [Revised: 09/12/2022] [Accepted: 09/12/2022] [Indexed: 11/11/2022] Open
Abstract
Geobacter species have great application potential in remediation processes and electrobiotechnology. In all applications, understanding the metabolism will enable target-oriented optimization of the processes. The typical electron donor and carbon source of the Geobacter species is acetate, while fumarate is the usual electron acceptor. Here, we could show that depending on the donor/acceptor ratio in batch cultivation of Geobacter sulfurreducens different product patterns occur. With a donor/acceptor ratio of 1:2.5 malate accumulated as an intermediate product but was metabolized to succinate subsequently. At the end of the cultivation, the ratio of fumarate consumed and succinate produced was approximately 1:1. When fumarate was added in excess, malate accumulated in the fermentation broth without further metabolization. After the addition of acetate to stationary cells, malate concentration decreased immediately and additional succinate was synthesized. Finally, it was shown that also resting cells of G. sulfurreducens could efficiently convert fumarate to malate without an additional electron donor. Overall, it was demonstrated that by altering the donor/acceptor ratio, targeted optimization of the metabolite conversion by G. sulfurreducens can be realized.
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Affiliation(s)
- Hanna Marianne Frühauf‐Wyllie
- Department of Chemical TechnologyDECHEMA ForschungsinstitutFrankfurt am MainGermany
- Technische Hochschule Mittelhessen, Institut für Bioverfahrenstechnik und Pharmazeutische TechnologieGießenGermany
| | - Dirk Holtmann
- Technische Hochschule Mittelhessen, Institut für Bioverfahrenstechnik und Pharmazeutische TechnologieGießenGermany
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13
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A new angle to control concentration profiles at electroactive biofilm interfaces: investigating a microfluidic perpendicular flow approach. Electrochim Acta 2022. [DOI: 10.1016/j.electacta.2022.141071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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14
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Shi XC, Tremblay PL, Xue M, Song X, Zhang T. Fumarate disproportionation by Geobacter sulfurreducens and its involvement in biocorrosion and interspecies electron transfer. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 827:154251. [PMID: 35245554 DOI: 10.1016/j.scitotenv.2022.154251] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 02/14/2022] [Accepted: 02/26/2022] [Indexed: 06/14/2023]
Abstract
The model electroactive bacterium Geobacter sulfurreducens can acquire electrons directly from solid donors including metals and other species. Reports on this physiology concluding that solid donors are the only electron sources were conducted with fumarate believed to serve exclusively as the terminal electron acceptor (TEA). Here, G. sulfurreducens was repeatedly transferred for adaptation within a growth medium containing only fumarate and no other solid or soluble substrate. The resulting evolved strain grew efficiently with either the C4-dicarboxylate fumarate or malate acting simultaneously as electron donor, carbon source, and electron acceptor via disproportionation. Whole-genome sequencing identified 38 mutations including one in the regulator PilR known to repress the expression of the C4-dicarboxylate antiporter DcuB essential to G. sulfurreducens when growing with fumarate. Futhermore, the PilR mutation was identical to the sole mutation previously reported in an evolved G. sulfurreducens grown in a co-culture assumed to derive energy solely from direct interspecies electron transfer, but cultivated with fumarate as the TEA. When cultivating the fumarate-adapted strain in the presence of stainless steel and fumarate, biocorrosion was observed and bacterial growth was accelerated 2.3 times. These results suggest that G. sulfurreducens can conserve energy concomitantly from C4-dicarboxylate disproportionation and the oxidation of a solid electron donor. This co-metabolic capacity confers an advantage to Geobacter for survival and colonization and explains in part why these microbes are omnipresent in different anaerobic ecosystems.
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Affiliation(s)
- Xiao-Chen Shi
- School of Chemistry, Chemical Engineering, and Life Science, Wuhan University of Technology, Wuhan 430070, PR China; School of Resources and Environmental Engineering, Wuhan University of Technology, Wuhan 430070, PR China; Wuhan University of Technology Advanced Engineering Technology Research Institute of Zhongshan City, Zhongshan 528437, PR China
| | - Pier-Luc Tremblay
- School of Chemistry, Chemical Engineering, and Life Science, Wuhan University of Technology, Wuhan 430070, PR China; State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070, PR China; Sanya Science and Education Innovation Park, Wuhan University of Technology, Sanya 572024, PR China
| | - Miao Xue
- Institut WUT-AMU, Wuhan University of Technology, Wuhan 430070, PR China
| | - Xinyi Song
- Institut WUT-AMU, Wuhan University of Technology, Wuhan 430070, PR China
| | - Tian Zhang
- School of Chemistry, Chemical Engineering, and Life Science, Wuhan University of Technology, Wuhan 430070, PR China; School of Resources and Environmental Engineering, Wuhan University of Technology, Wuhan 430070, PR China; Institut WUT-AMU, Wuhan University of Technology, Wuhan 430070, PR China; State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070, PR China; Sanya Science and Education Innovation Park, Wuhan University of Technology, Sanya 572024, PR China.
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15
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Antunes JMA, Silva MA, Salgueiro CA, Morgado L. Electron Flow From the Inner Membrane Towards the Cell Exterior in Geobacter sulfurreducens: Biochemical Characterization of Cytochrome CbcL. Front Microbiol 2022; 13:898015. [PMID: 35620088 PMCID: PMC9129911 DOI: 10.3389/fmicb.2022.898015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 04/04/2022] [Indexed: 11/25/2022] Open
Abstract
Exoelectrogenic microorganisms are in the spotlight due to their unique respiratory mechanisms and potential applications in distinct biotechnological fields, including bioremediation, bioenergy production and microbial electrosynthesis. These applications rely on the capability of these microorganisms to perform extracellular electron transfer, a mechanism that allows the bacteria to transfer electrons to the cell’s exterior by establishing functional interfaces between different multiheme cytochromes at the inner membrane, periplasmic space, and outer membrane. The multiheme cytochrome CbcL from Geobacter sulfurreducens is associated to the inner membrane and plays an essential role in the transfer of electrons to final electron acceptors with a low redox potential, as Fe(III) oxides and electrodes poised at −100 mV. CbcL has a transmembranar di-heme b-type cytochrome domain with six helices, linked to a periplasmic cytochrome domain with nine c-type heme groups. The complementary usage of ultraviolet-visible, circular dichroism and nuclear magnetic resonance permitted the structural and functional characterization of CbcL’s periplasmic domain. The protein was found to have a high percentage of disordered regions and its nine hemes are low-spin and all coordinated by two histidine residues. The apparent midpoint reduction potential of the CbcL periplasmic domain was determined, suggesting a thermodynamically favorable transfer of electrons to the putative redox partner in the periplasm − the triheme cytochrome PpcA. The establishment of a redox complex between the two proteins was confirmed by probing the electron transfer reaction and the molecular interactions between CbcL and PpcA. The results obtained show for the first time how electrons are injected into the periplasm of Geobacter sulfurreducens for subsequent transfer to the cell’s exterior.
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Affiliation(s)
- Jorge M A Antunes
- Associate Laboratory i4HB - Institute for Health and Bioeconomy, NOVA School of Science and Technology, NOVA University Lisbon, Caparica, Portugal.,UCIBIO - Applied Molecular Biosciences Unit, Chemistry Department, NOVA School of Science and Technology, NOVA University Lisbon, Caparica, Portugal
| | - Marta A Silva
- Associate Laboratory i4HB - Institute for Health and Bioeconomy, NOVA School of Science and Technology, NOVA University Lisbon, Caparica, Portugal.,UCIBIO - Applied Molecular Biosciences Unit, Chemistry Department, NOVA School of Science and Technology, NOVA University Lisbon, Caparica, Portugal
| | - Carlos A Salgueiro
- Associate Laboratory i4HB - Institute for Health and Bioeconomy, NOVA School of Science and Technology, NOVA University Lisbon, Caparica, Portugal.,UCIBIO - Applied Molecular Biosciences Unit, Chemistry Department, NOVA School of Science and Technology, NOVA University Lisbon, Caparica, Portugal
| | - Leonor Morgado
- Associate Laboratory i4HB - Institute for Health and Bioeconomy, NOVA School of Science and Technology, NOVA University Lisbon, Caparica, Portugal.,UCIBIO - Applied Molecular Biosciences Unit, Chemistry Department, NOVA School of Science and Technology, NOVA University Lisbon, Caparica, Portugal
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16
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Li C, Feng Y, Liang D, Zhang L, Tian Y, Yadav RS, He W. Spatial-type skeleton induced Geobacter enrichment and tailored bio-capacitance of electroactive bioanode for efficient electron transfer in microbial fuel cells. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 821:153123. [PMID: 35051486 DOI: 10.1016/j.scitotenv.2022.153123] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2021] [Revised: 01/08/2022] [Accepted: 01/10/2022] [Indexed: 06/14/2023]
Abstract
Microbial fuel cell (MFC) is a promising alternative to energy-intensive conventional wastewater technology. However, poor electron transfer efficiency, low coulombic recovery (CR), and high capital cost highly restricted its practical application. In this work, spatial electroactive biofilm is successfully developed on the carbonaceous skeleton derived from phenolic foam, which highly improved the bio-capacitance and Geobacter abundance of bioanode. Compared with carbon cloth (CC) anode, the optimal spatial electroactive biofilm (3DP_900) enriched the Geobacter abundance up to 56.8% from 17.2%, and obtained an extraordinary electroactive biomass loading of about 339 ± 63 μg cm-2 and a remarkable bio-capacitance of about 3.4 F. In general, spatial biofilm highly reduces the barriers to electron transfer (Rct) and mass transfer (Rd) in anodic substrate oxidation reaction and obtains the lowest Rct of 2.0 ± 0.2 Ω and Rd of 35 ± 3.3 Ω in 3DP_900, which also supports the highest power density at 0.347 ± 0.027 W m-2 and the highest CR at 69.2%. More importantly, due to its mature preparation technology, carbonized phenolic foam (2 cm thick pieces) reduces the capital cost of electrode preparation by three orders of magnitude from 1157.3 USD m-2 of CC to 5.2 USD m-2. Overall, this work offers an effective and scalable electrode to achieve high substrate utilization rate and energy recovery efficiency, and considers the economic cost of electrode fabrication for the further construction of pilot-scale MFCs equipment.
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Affiliation(s)
- Chao Li
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, No. 73 Huanghe Road, Nangang District, Harbin 150090, China
| | - Yujie Feng
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, No. 73 Huanghe Road, Nangang District, Harbin 150090, China
| | - Dandan Liang
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, No. 73 Huanghe Road, Nangang District, Harbin 150090, China
| | - Lijuan Zhang
- School of Environmental and Energy, Guangdong Provincial Key Laboratory of Solid Wastes Pollution Control and Recycling, South China University of Technology, Guangzhou, Guangdong 510006, China
| | - Yan Tian
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, No. 73 Huanghe Road, Nangang District, Harbin 150090, China
| | - Ravi Shankar Yadav
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, No. 73 Huanghe Road, Nangang District, Harbin 150090, China
| | - Weihua He
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, No. 73 Huanghe Road, Nangang District, Harbin 150090, China.
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17
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Kuchenbuch A, Frank R, Ramos JV, Jahnke HG, Harnisch F. Electrochemical Microwell Plate to Study Electroactive Microorganisms in Parallel and Real-Time. Front Bioeng Biotechnol 2022; 9:821734. [PMID: 35242754 PMCID: PMC8887713 DOI: 10.3389/fbioe.2021.821734] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 12/28/2021] [Indexed: 11/26/2022] Open
Abstract
Microbial resource mining of electroactive microorganism (EAM) is currently methodically hampered due to unavailable electrochemical screening tools. Here, we introduce an electrochemical microwell plate (ec-MP) composed of a 96 electrochemical deepwell plate and a recently developed 96-channel multipotentiostat. Using the ec-MP we investigated the electrochemical and metabolic properties of the EAM models Shewanella oneidensis and Geobacter sulfurreducens with acetate and lactate as electron donor combined with an individual genetic analysis of each well. Electrochemical cultivation of pure cultures achieved maximum current densities (j max) and coulombic efficiencies (CE) that were well in line with literature data. The co-cultivation of S. oneidensis and G. sulfurreducens led to an increased current density of j max of 88.57 ± 14.04 µA cm-2 (lactate) and j max of 99.36 ± 19.12 µA cm-2 (lactate and acetate). Further, a decreased time period of reaching j max and biphasic current production was revealed and the microbial electrochemical performance could be linked to the shift in the relative abundance.
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Affiliation(s)
- Anne Kuchenbuch
- Department of Environmental Microbiology, UFZ—Helmholtz-Centre for Environmental Research GmbH, Leipzig, Germany
| | - Ronny Frank
- Centre for Biotechnology and Biomedicine, Molecular Biological-Biochemical Processing Technology, Leipzig University, Leipzig, Germany
| | - José Vazquez Ramos
- Centre for Biotechnology and Biomedicine, Molecular Biological-Biochemical Processing Technology, Leipzig University, Leipzig, Germany
| | - Heinz-Georg Jahnke
- Centre for Biotechnology and Biomedicine, Molecular Biological-Biochemical Processing Technology, Leipzig University, Leipzig, Germany
| | - Falk Harnisch
- Department of Environmental Microbiology, UFZ—Helmholtz-Centre for Environmental Research GmbH, Leipzig, Germany
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18
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Aiken DC, Curtis TP, Heidrich ES. The Rational Design of a Financially Viable Microbial Electrolysis Cell for Domestic Wastewater Treatment. FRONTIERS IN CHEMICAL ENGINEERING 2022. [DOI: 10.3389/fceng.2021.796805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Microbial electrolysis cells (MECs) are yet to achieve commercial viability. Organic removal rates (ORR) and capital costs dictate an MEC’s financial competitiveness against activated sludge treatments. We used numerical methods to investigate the impact of acetate concentration and the distance between opposing anodes’ surfaces (anode interstices width) on MEC cost-performance. Numerical predictions were calibrated against laboratory observations using an evolutionary algorithm. Anode interstices width had a non-linear impact on ORR and therefore allowable cost. MECs could be financially competitive if anode interstices widths are carefully controlled (2.5 mm), material costs kept low (£5–10/m2-anode), and wastewater pre-treated, using hydrolysis to consistently achieve influent acetate concentrations >100 mg-COD/l.
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19
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Massazza D, Robledo AJ, Rodriguez Simón CN, Busalmen JP, Bonanni S. Energetics, electron uptake mechanisms and limitations of electroautotrophs growing on biocathodes - A review. BIORESOURCE TECHNOLOGY 2021; 342:125893. [PMID: 34537530 DOI: 10.1016/j.biortech.2021.125893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2021] [Revised: 08/31/2021] [Accepted: 09/03/2021] [Indexed: 06/13/2023]
Abstract
Electroautotrophs are microorganisms that can take the electrons needed for energy generation, CO2 fixation and other metabolic reactions from a polarized electrode. They have been the focus of intense research for its application in wastewater treatment, bioelectrosynthetic processes and hydrogen generation. As a general trend, current densities produced by the electron uptake of these microorganisms are low, limiting their applicability at large scale. In this work, the electron uptake mechanisms that may operate in electroautotrophs are reviewed, aiming at finding possible causes for this low performance. Biomass yields, growth rates and electron uptake rates observed when these microorganisms use chemical electron donors are compared with those typically obtained with electrodes, to explore limitations and advantages inherent to the electroautotrophic metabolism. Also, the factors affecting biofilm development are analysed to show how interfacial interactions condition bacterial adhesion, biofilm growth and electrons uptake. Finally, possible strategies to overcome these limitations are described.
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Affiliation(s)
- Diego Massazza
- División Ingeniería de Interfases y Bioprocesos, INTEMA (Conicet, Universidad Nacional de Mar del Plata), Av. Colón 10850, Mar del Plata 7600, Argentina
| | - Alejandro Javier Robledo
- División Ingeniería de Interfases y Bioprocesos, INTEMA (Conicet, Universidad Nacional de Mar del Plata), Av. Colón 10850, Mar del Plata 7600, Argentina
| | - Carlos Norberto Rodriguez Simón
- División Ingeniería de Interfases y Bioprocesos, INTEMA (Conicet, Universidad Nacional de Mar del Plata), Av. Colón 10850, Mar del Plata 7600, Argentina
| | - Juan Pablo Busalmen
- División Ingeniería de Interfases y Bioprocesos, INTEMA (Conicet, Universidad Nacional de Mar del Plata), Av. Colón 10850, Mar del Plata 7600, Argentina
| | - Sebastián Bonanni
- División Ingeniería de Interfases y Bioprocesos, INTEMA (Conicet, Universidad Nacional de Mar del Plata), Av. Colón 10850, Mar del Plata 7600, Argentina.
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20
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Clark MM, Paxhia MD, Young JM, Manzella MP, Reguera G. Adaptive Synthesis of a Rough Lipopolysaccharide in Geobacter sulfurreducens for Metal Reduction and Detoxification. Appl Environ Microbiol 2021; 87:e0096421. [PMID: 34347518 PMCID: PMC8478458 DOI: 10.1128/aem.00964-21] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2021] [Accepted: 07/31/2021] [Indexed: 11/20/2022] Open
Abstract
The ability of some metal-reducing bacteria to produce a rough (no O-antigen) lipopolysaccharide (LPS) could facilitate surface interactions with minerals and metal reduction. Consistent with this, the laboratory model metal reducer Geobacter sulfurreducens PCA produced two rough LPS isoforms (with or without a terminal methyl-quinovosamine sugar) when growing with the soluble electron acceptor fumarate but expressed only the shorter and more hydrophilic variant when reducing iron oxides. We reconstructed from genomic data conserved pathways for the synthesis of the rough LPS and generated heptosyltransferase mutants with partial (ΔrfaQ) or complete (ΔrfaC) truncations in the core oligosaccharide. The stepwise removal of the LPS core sugars reduced the hydrophilicity of the cell and increased outer membrane vesiculation. These changes in surface charge and remodeling did not substantially impact planktonic growth but disrupted the developmental stages and structure of electroactive biofilms. Furthermore, the mutants assembled conductive pili for extracellular mineralization of the toxic uranyl cation but were unable to prevent permeation and mineralization of the radionuclide in the cell envelope. Hence, not only does the rough LPS promote cell-cell and cell-mineral interactions critical to biofilm formation and metal respiration but it also functions as a permeability barrier to toxic metal cations. In doing so, the rough LPS maximizes the extracellular reduction of soluble and insoluble metals and preserves cell envelope functions critical to the environmental survival of Geobacter bacteria in metal-rich environments and their performance in bioremediation and bioenergy applications. IMPORTANCE Some metal-reducing bacteria produce an LPS without the repeating sugars (O-antigen) that decorate the surface of most Gram-negative bacteria, but the biological significance of this adaptive feature was not previously investigated. Using the model representative Geobacter sulfurreducens strain PCA and mutants carrying stepwise truncations in the LPS core sugars, we demonstrate the importance of the rough LPS in the control of cell surface chemistry during the respiration of iron minerals and the formation of electroactive biofilms. Importantly, we describe hitherto overlooked roles for the rough LPS in metal sequestration and outer membrane vesiculation that are critical for the extracellular reduction and detoxification of toxic metals and radionuclides. These results are of interest for the optimization of bioremediation schemes and electricity-harvesting platforms using these bacteria.
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Affiliation(s)
- Morgen M. Clark
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA
| | - Michael D. Paxhia
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA
| | - Jenna M. Young
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA
| | - Michael P. Manzella
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA
| | - Gemma Reguera
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA
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21
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Berger S, Shaw DR, Berben T, Ouboter HT, In 't Zandt MH, Frank J, Reimann J, Jetten MSM, Welte CU. Current production by non-methanotrophic bacteria enriched from an anaerobic methane-oxidizing microbial community. Biofilm 2021; 3:100054. [PMID: 34308332 PMCID: PMC8258643 DOI: 10.1016/j.bioflm.2021.100054] [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: 01/29/2021] [Revised: 04/12/2021] [Accepted: 05/19/2021] [Indexed: 12/21/2022] Open
Abstract
In recent years, the externalization of electrons as part of respiratory metabolic processes has been discovered in many different bacteria and some archaea. Microbial extracellular electron transfer (EET) plays an important role in many anoxic natural or engineered ecosystems. In this study, an anaerobic methane-converting microbial community was investigated with regard to its potential to perform EET. At this point, it is not well-known if or how EET confers a competitive advantage to certain species in methane-converting communities. EET was investigated in a two-chamber electrochemical system, sparged with methane and with an applied potential of +400 mV versus standard hydrogen electrode. A biofilm developed on the working electrode and stable low-density current was produced, confirming that EET indeed did occur. The appearance and presence of redox centers at −140 to −160 mV and at −230 mV in the biofilm was confirmed by cyclic voltammetry scans. Metagenomic analysis and fluorescence in situ hybridization of the biofilm showed that the anaerobic methanotroph ‘Candidatus Methanoperedens BLZ2’ was a significant member of the biofilm community, but its relative abundance did not increase compared to the inoculum. On the contrary, the relative abundance of other members of the microbial community significantly increased (up to 720-fold, 7.2% of mapped reads), placing these microorganisms among the dominant species in the bioanode community. This group included Zoogloea sp., Dechloromonas sp., two members of the Bacteroidetes phylum, and the spirochete Leptonema sp. Genes encoding proteins putatively involved in EET were identified in Zoogloea sp., Dechloromonas sp. and one member of the Bacteroidetes phylum. We suggest that instead of methane, alternative carbon sources such as acetate were the substrate for EET. Hence, EET in a methane-driven chemolithoautotrophic microbial community seems a complex process in which interactions within the microbial community are driving extracellular electron transfer to the electrode.
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Affiliation(s)
- S Berger
- Institute for Water and Wetland Research, Department of Microbiology, Radboud University, Nijmegen, the Netherlands
| | - D R Shaw
- Biological and Environmental Science and Engineering Division, Water Desalination and Reuse Research Center, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia.,Soehngen Institute of Anaerobic Microbiology, Radboud University, Nijmegen, the Netherlands
| | - T Berben
- Institute for Water and Wetland Research, Department of Microbiology, Radboud University, Nijmegen, the Netherlands
| | - H T Ouboter
- Institute for Water and Wetland Research, Department of Microbiology, Radboud University, Nijmegen, the Netherlands.,Soehngen Institute of Anaerobic Microbiology, Radboud University, Nijmegen, the Netherlands
| | - M H In 't Zandt
- Institute for Water and Wetland Research, Department of Microbiology, Radboud University, Nijmegen, the Netherlands.,Netherlands Earth System Science Center, Utrecht University, Utrecht, the Netherlands
| | - J Frank
- Institute for Water and Wetland Research, Department of Microbiology, Radboud University, Nijmegen, the Netherlands.,Soehngen Institute of Anaerobic Microbiology, Radboud University, Nijmegen, the Netherlands
| | - J Reimann
- Institute for Water and Wetland Research, Department of Microbiology, Radboud University, Nijmegen, the Netherlands
| | - M S M Jetten
- Institute for Water and Wetland Research, Department of Microbiology, Radboud University, Nijmegen, the Netherlands.,Netherlands Earth System Science Center, Utrecht University, Utrecht, the Netherlands.,Soehngen Institute of Anaerobic Microbiology, Radboud University, Nijmegen, the Netherlands
| | - C U Welte
- Institute for Water and Wetland Research, Department of Microbiology, Radboud University, Nijmegen, the Netherlands.,Soehngen Institute of Anaerobic Microbiology, Radboud University, Nijmegen, the Netherlands
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22
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Speers AM, Reguera G. Competitive advantage of oxygen-tolerant bioanodes of Geobacter sulfurreducens in bioelectrochemical systems. Biofilm 2021; 3:100052. [PMID: 34222855 PMCID: PMC8242959 DOI: 10.1016/j.bioflm.2021.100052] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 05/18/2021] [Accepted: 05/19/2021] [Indexed: 10/31/2022] Open
Abstract
Oxidative stress greatly limits current harvesting from anode biofilms in bioelectrochemical systems yet insufficient knowledge of the antioxidant responses of electricigens prevents optimization. Using Geobacter sulfurreducens PCA as a model electricigen, we demonstrated enhanced oxygen tolerance and reduced electron losses as the biofilms grew in height on the anode. To investigate the molecular basis of biofilm tolerance, we developed a genetic screening and isolated 11 oxygen-tolerant (oxt) strains from a library of transposon-insertion mutants. The aggregative properties of the oxt mutants promoted biofilm formation and oxygen tolerance. Yet, unlike the wild type, none of the mutants diverted respiratory electrons to oxygen. Most of the oxt mutations inactivated pathways for the detoxification of reactive oxygen species that could have triggered compensatory chronic responses to oxidative stress and inhibit aerobic respiration. One of the mutants (oxt10) also had a growth advantage with Fe(III) oxides and during the colonization of the anode electrode. The enhanced antioxidant response in this mutant reduced the system's start-up and promoted current harvesting from bioanodes even in the presence of oxygen. These results highlight a hitherto unknown role of oxidative stress responses in the stability and performance of current-harvesting biofilms of G. sulfurreducens and identify biological and engineering approaches to grow electroactive biofilms with the resilience needed for practical applications.
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Affiliation(s)
- Allison M Speers
- Department of Microbiology and Molecular Genetics, Michigan State University, USA
| | - Gemma Reguera
- Department of Microbiology and Molecular Genetics, Michigan State University, USA
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23
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Sapireddy V, Katuri KP, Muhammad A, Saikaly PE. Competition of two highly specialized and efficient acetoclastic electroactive bacteria for acetate in biofilm anode of microbial electrolysis cell. NPJ Biofilms Microbiomes 2021; 7:47. [PMID: 34059681 PMCID: PMC8166840 DOI: 10.1038/s41522-021-00218-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 04/07/2021] [Indexed: 02/04/2023] Open
Abstract
Maintaining functional stability of microbial electrolysis cell (MEC) treating wastewater depends on maintaining functional redundancy of efficient electroactive bacteria (EAB) on the anode biofilm. Therefore, investigating whether efficient EAB competing for the same resources (electron donor and acceptor) co-exist at the anode biofilm is key for the successful application of MEC for wastewater treatment. Here, we compare the electrochemical and kinetic properties of two efficient acetoclastic EAB, Geobacter sulfurreducens (GS) and Desulfuromonas acetexigens (DA), grown as monoculture in MECs fed with acetate. Additionally, we monitor the evolution of DA and GS in co-culture MECs fed with acetate or domestic wastewater using fluorescent in situ hybridization. The apparent Monod kinetic parameters reveal that DA possesses higher jmax (10.7 ± 0.4 A/m2) and lower KS, app (2 ± 0.15 mM) compared to GS biofilms (jmax: 9.6 ± 0.2 A/m2 and KS, app: 2.9 ± 0.2 mM). Further, more donor electrons are diverted to the anode for respiration in DA compared to GS. In acetate-fed co-culture MECs, DA (98% abundance) outcompete GS for anode-dependent growth. In contrast, both EAB co-exist (DA: 55 ± 2%; GS: 24 ± 1.1%) in wastewater-fed co-culture MECs despite the advantage of DA over GS based on kinetic parameters alone. The co-existence of efficient acetoclastic EAB with high current density in MECs fed with wastewater is significant in the context of functional redundancy to maintain stable performance. Our findings also provide insight to future studies on bioaugmentation of wastewater-fed MECs with efficient EAB to enhance performance.
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Affiliation(s)
- Veerraghavulu Sapireddy
- Biological and Environmental Science and Engineering Division, Water Desalination and Reuse Center, King Abdullah University of Science and Technology, Thuwal, 23955-6900, Saudi Arabia
| | - Krishna P Katuri
- Biological and Environmental Science and Engineering Division, Water Desalination and Reuse Center, King Abdullah University of Science and Technology, Thuwal, 23955-6900, Saudi Arabia.
| | - Ali Muhammad
- Biological and Environmental Science and Engineering Division, Water Desalination and Reuse Center, King Abdullah University of Science and Technology, Thuwal, 23955-6900, Saudi Arabia
| | - Pascal E Saikaly
- Biological and Environmental Science and Engineering Division, Water Desalination and Reuse Center, King Abdullah University of Science and Technology, Thuwal, 23955-6900, Saudi Arabia.
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24
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Cologgi DL, Otwell AE, Speers AM, Rotondo JA, Reguera G. Genetic analysis of electroactive biofilms. Int Microbiol 2021; 24:631-648. [PMID: 33907940 DOI: 10.1007/s10123-021-00176-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 04/01/2021] [Accepted: 04/08/2021] [Indexed: 12/17/2022]
Abstract
Geobacter biofilms synthesize an electroactive exopolysaccharide matrix with conductive pili and c-cytochromes that spatially organizes cells optimally for growth and electron transport to iron oxide substrates, soluble metal contaminants, and current-harvesting electrodes. Despite its relevance to bioremediation and bioenergy applications, little is known about the developmental stages leading to the formation of mature (>20 μm thick) electroactive biofilms. Thus, we developed a transposon mutagenesis method and a high-throughput screening assay and identified mutants of Geobacter sulfurreducens PCA interrupted in the initial stages of surface colonization (attachment and monolayer formation) and the vertical growth and maturation of multilayered biofilms. The molecular dissection of biofilm formation demonstrated that cells undergo a regulated developmental program to first colonize the surface to saturation and then synthesize an electroactive matrix to support optimal cell growth within structured communities. Transitioning from a monolayer to a multilayered, mature biofilm required the expression of conductive pili, consistent with the essential role of these extracellular protein appendages as electronic conduits across all layers of the biofilms. The genetic screening also identified cell envelope processes, regulatory pathways, and electron transport components not previously linked to biofilm formation. These genes provide much-needed understanding of the cellular reprogramming needed to build electroactive biofilms. Importantly, they serve as predictive markers of the physiology and reductive capacity of Geobacter biofilms during the bioremediation of toxic metals and radionuclides and current harvesting in bioelectrochemical systems.
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Affiliation(s)
- Dena L Cologgi
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, 48824, USA
| | - Anne E Otwell
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, 48824, USA.,Present address: Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, 98195, USA
| | - Allison M Speers
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, 48824, USA
| | - John A Rotondo
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, 48824, USA
| | - Gemma Reguera
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, 48824, USA.
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25
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Ndayisenga F, Yu Z, Yan G, Phulpoto IA, Li Q, Kumar H, Fu L, Zhou D. Using easy-to-biodegrade co-substrate to eliminate microcystin toxic on electrochemically active bacteria and enhance bioelectricity generation from cyanobacteria biomass. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 751:142292. [PMID: 33182012 DOI: 10.1016/j.scitotenv.2020.142292] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 09/06/2020] [Accepted: 09/07/2020] [Indexed: 06/11/2023]
Abstract
Cyanobacterial biomass is a promising natural resource for power generation, through the reactions bio-catalyzed by electrochemically active bacteria (EAB). However, the major limitation is the involvement of Microcystin-LR (MC-LR) in inhibiting EAB activation. In this work, toxic M. aeruginosa biomass was employed as analyte of a microbial fuel cell (MFC), and sodium acetate was applied as easy-to-biodegrade co-substrate to alleviate the MC-LR stress on EAB survival. The running stability was continuously enhanced with the increment of co-substrate concentration. The sufficient co-substrate supply (6.0 mM) eliminated the negative effects of MC-LR on the cyanobacteria biomass fed-MFC performance; it contributed 12.7% extension on the electric cyclic terms and caused the productions of the power density which was comparable and even 3.8% higher than its corresponding control (MFC treated with acetate alone). The co-substrate addition also increased coulombic efficiency by 60.1%, microcystin-LR removal efficiency increased by 64.7%, and diversified the microbial community with more species able to biodegrade the MC-LR, bio-transforming the metabolites and EAB. Microcystin-degrading bacteria, such as Sphingopyxis sp., Burkholderia-Paraburkholderia, and Bacillus sp., were remarkably increased, and EAB, including Shewanella sp., Desulfovibrio desulfuricans, Aeromonas hydrophila, were also much more enriched in co-substrate use protocol. Therefore, this study verified a co-substrate strategy for simultaneously eliminating MC-LR toxin and enhancing bioelectricity generation from cyanobacterial biomass via an MFC.
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Affiliation(s)
- Fabrice Ndayisenga
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China; Engineering Lab for Water Pollution Control and Resources Recovery of Jilin Province, School of Environment, Northeast Normal University, Changchun 130117, China
| | - Zhisheng Yu
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Ge Yan
- Engineering Lab for Water Pollution Control and Resources Recovery of Jilin Province, School of Environment, Northeast Normal University, Changchun 130117, China
| | - Irfan Ali Phulpoto
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qingcheng Li
- Engineering Lab for Water Pollution Control and Resources Recovery of Jilin Province, School of Environment, Northeast Normal University, Changchun 130117, China; State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, PR China
| | - Haresh Kumar
- Engineering Lab for Water Pollution Control and Resources Recovery of Jilin Province, School of Environment, Northeast Normal University, Changchun 130117, China
| | - Liang Fu
- Engineering Lab for Water Pollution Control and Resources Recovery of Jilin Province, School of Environment, Northeast Normal University, Changchun 130117, China
| | - Dandan Zhou
- Engineering Lab for Water Pollution Control and Resources Recovery of Jilin Province, School of Environment, Northeast Normal University, Changchun 130117, China.
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26
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Key Enzymes for Anaerobic Lactate Metabolism in Geobacter sulfurreducens. Appl Environ Microbiol 2021; 87:AEM.01968-20. [PMID: 33158892 DOI: 10.1128/aem.01968-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 09/22/2020] [Indexed: 11/20/2022] Open
Abstract
Growth of Geobacter sulfurreducens PCA on lactate was enhanced by laboratory adaptive evolution. The enhanced growth was considered to be attributed to increased expression of the sucCD genes, encoding a succinyl-coenzyme A (CoA) synthetase. To further investigate the function of the succinyl-CoA synthetase, the sucCD genes were deleted from G. sulfurreducens The mutant showed defective growth on lactate but not on acetate. Introduction of the sucCD genes into the mutant restored the full potential to grow on lactate. These results verify the importance of the succinyl-CoA synthetase in growth on lactate. Genome analysis of Geobacter species identified candidate genes, GSU1623, GSU1624, and GSU1620, for lactate dehydrogenase. Deletion mutants of the identified genes for d-lactate dehydrogenase (ΔGSU1623 ΔGSU1624 mutant) or l-lactate dehydrogenase (ΔGSU1620 mutant) could not grow on d-lactate or l-lactate but could grow on acetate and l- or d-lactate, respectively. Introduction of the respective genes into the mutants allowed growth on the corresponding lactate stereoisomer. These results suggest that the identified genes were essential for d- or l-lactate utilization. The lacZ reporter assay demonstrated that the putative promoter regions were more active during growth on lactate than during growth on acetate, indicating that the genes for the lactate dehydrogenases were expressed more during growth on lactate than during growth on acetate. The gene deletion phenotypes and the expression profiles indicate that there are metabolic switches between lactate and acetate. This study advances the understanding of anaerobic lactate utilization in G. sulfurreducens IMPORTANCE Lactate is a microbial fermentation product as well as a source of carbon and electrons for microorganisms in the environment. Furthermore, lactate is a common amendment for stimulation of microbial growth in environmental biotechnology applications. However, anaerobic metabolism of lactate has been poorly studied for environmentally relevant microorganisms. Geobacter species are found in various environments and environmental biotechnology applications. By employing genomic and genetic approaches, succinyl-CoA synthetase and lactate dehydrogenase were identified as key enzymes in anaerobic metabolism of lactate in Geobacter sulfurreducens, a representative Geobacter species. Differential gene expression during growth on lactate and acetate was observed, demonstrating that G. sulfurreducens could metabolically switch to adapt to available substrates in the environment. The findings provide new insights into basic physiology in lactate metabolism as well as cellular responses to growth conditions in the environment and can be informative for the application of lactate in environmental biotechnology.
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27
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Dulay H, Tabares M, Kashefi K, Reguera G. Cobalt Resistance via Detoxification and Mineralization in the Iron-Reducing Bacterium Geobacter sulfurreducens. Front Microbiol 2020; 11:600463. [PMID: 33324382 PMCID: PMC7726332 DOI: 10.3389/fmicb.2020.600463] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Accepted: 11/03/2020] [Indexed: 12/18/2022] Open
Abstract
Bacteria in the genus Geobacter thrive in iron- and manganese-rich environments where the divalent cobalt cation (CoII) accumulates to potentially toxic concentrations. Consistent with selective pressure from environmental exposure, the model laboratory representative Geobacter sulfurreducens grew with CoCl2 concentrations (1 mM) typically used to enrich for metal-resistant bacteria from contaminated sites. We reconstructed from genomic data canonical pathways for CoII import and assimilation into cofactors (cobamides) that support the growth of numerous syntrophic partners. We also identified several metal efflux pumps, including one that was specifically upregulated by CoII. Cells acclimated to metal stress by downregulating non-essential proteins with metals and thiol groups that CoII preferentially targets. They also activated sensory and regulatory proteins involved in detoxification as well as pathways for protein and DNA repair. In addition, G. sulfurreducens upregulated respiratory chains that could have contributed to the reductive mineralization of the metal on the cell surface. Transcriptomic evidence also revealed pathways for cell envelope modification that increased metal resistance and promoted cell-cell aggregation and biofilm formation in stationary phase. These complex adaptive responses confer on Geobacter a competitive advantage for growth in metal-rich environments that are essential to the sustainability of cobamide-dependent microbiomes and the sequestration of the metal in hitherto unknown biomineralization reactions.
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Affiliation(s)
- Hunter Dulay
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, United States
| | - Marcela Tabares
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, United States
| | - Kazem Kashefi
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, United States
| | - Gemma Reguera
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, United States
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28
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Mollaei M, Timmers PHA, Suarez-Diez M, Boeren S, van Gelder AH, Stams AJM, Plugge CM. Comparative proteomics of Geobacter sulfurreducens PCA T in response to acetate, formate and/or hydrogen as electron donor. Environ Microbiol 2020; 23:299-315. [PMID: 33185968 PMCID: PMC7894505 DOI: 10.1111/1462-2920.15311] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 10/19/2020] [Accepted: 11/06/2020] [Indexed: 12/11/2022]
Abstract
Geobacter sulfurreducens is a model bacterium to study the degradation of organic compounds coupled to the reduction of Fe(III). The response of G. sulfurreducens to the electron donors acetate, formate, hydrogen and a mixture of all three with Fe(III) citrate as electron acceptor was studied using comparative physiological and proteomic approaches. Variations in the supplied electron donors resulted in differential abundance of proteins involved in the citric acid cycle (CAC), gluconeogenesis, electron transport, and hydrogenases and formate dehydrogenase. Our results provided new insights into the electron donor metabolism of G. sulfurreducens. Remarkably, formate was the preferred electron donor compared to acetate, hydrogen, or acetate plus hydrogen. When hydrogen was the electron donor, formate was formed, which was associated with a high abundance of formate dehydrogenase. Notably, abundant proteins of two CO2 fixation pathways (acetyl-CoA pathway and the reversed oxidative CAC) corroborated chemolithoautotrophic growth of G. sulfurreducens with formate or hydrogen and CO2 , and provided novel insight into chemolithoautotrophic growth of G. sulfurreducens.
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Affiliation(s)
- Monir Mollaei
- Wetsus, European Centre of Excellence for Sustainable Water Technology, Leeuwarden, The Netherlands.,Laboratory of Microbiology, Wageningen University & Research, Wageningen, The Netherlands
| | - Peer H A Timmers
- Wetsus, European Centre of Excellence for Sustainable Water Technology, Leeuwarden, The Netherlands.,Laboratory of Microbiology, Wageningen University & Research, Wageningen, The Netherlands
| | - Maria Suarez-Diez
- Laboratory of Systems and Synthetic Biology, Wageningen University & Research, Wageningen, The Netherlands
| | - Sjef Boeren
- Laboratory of Biochemistry, Wageningen University & Research, Wageningen, The Netherlands
| | - Antonie H van Gelder
- Laboratory of Microbiology, Wageningen University & Research, Wageningen, The Netherlands
| | - Alfons J M Stams
- Laboratory of Microbiology, Wageningen University & Research, Wageningen, The Netherlands.,Centre of Biological Engineering, University of Minho, Braga, Portugal
| | - Caroline M Plugge
- Wetsus, European Centre of Excellence for Sustainable Water Technology, Leeuwarden, The Netherlands.,Laboratory of Microbiology, Wageningen University & Research, Wageningen, The Netherlands
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29
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Chen H, Simoska O, Lim K, Grattieri M, Yuan M, Dong F, Lee YS, Beaver K, Weliwatte S, Gaffney EM, Minteer SD. Fundamentals, Applications, and Future Directions of Bioelectrocatalysis. Chem Rev 2020; 120:12903-12993. [DOI: 10.1021/acs.chemrev.0c00472] [Citation(s) in RCA: 118] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Hui Chen
- Department of Chemistry, University of Utah, 315 South 1400 East, RM 2020, Salt Lake City, Utah 84112, United States
| | - Olja Simoska
- Department of Chemistry, University of Utah, 315 South 1400 East, RM 2020, Salt Lake City, Utah 84112, United States
| | - Koun Lim
- Department of Chemistry, University of Utah, 315 South 1400 East, RM 2020, Salt Lake City, Utah 84112, United States
| | - Matteo Grattieri
- Department of Chemistry, University of Utah, 315 South 1400 East, RM 2020, Salt Lake City, Utah 84112, United States
| | - Mengwei Yuan
- Department of Chemistry, University of Utah, 315 South 1400 East, RM 2020, Salt Lake City, Utah 84112, United States
| | - 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
| | - Kevin Beaver
- Department of Chemistry, University of Utah, 315 South 1400 East, RM 2020, Salt Lake City, Utah 84112, United States
| | - Samali Weliwatte
- 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
| | - Shelley D. Minteer
- Department of Chemistry, University of Utah, 315 South 1400 East, RM 2020, Salt Lake City, Utah 84112, United States
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30
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Clark MM, Reguera G. Biology and biotechnology of microbial pilus nanowires. J Ind Microbiol Biotechnol 2020; 47:897-907. [PMID: 33009965 DOI: 10.1007/s10295-020-02312-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 09/08/2020] [Indexed: 12/11/2022]
Abstract
Type IV pili (T4P) are bacterial appendages used for cell adhesion and surface motility. In metal-reducing bacteria in the genus Geobacter, they have the unique property of being conductive and essential to wire cells to extracellular electron acceptors and other cells within biofilms. These electroactive bacteria use a conserved pathway for biological assembly and disassembly of a short and aromatic dense peptide subunit (pilin). The polymerization of the pilins clusters aromatic residues optimally for charge transport and exposes ligands for metal immobilization and reduction. The simple design yet unique functionalities of conductive T4P afford opportunities for the scaled-up production of recombinant pilins and their in vitro assembly into electronic biomaterials of biotechnological interest. This review summarizes current knowledge of conductive T4P biogenesis and functions critical to actualize applications in bioelectronics, bioremediation, and nanotechnology.
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Affiliation(s)
- Morgen M Clark
- Department of Microbiology and Molecular Genetics, Michigan State University, 567 Wilson Rd, Rm 6190, Biomedical and Physical Science Building, East Lansing, MI, 48823, USA
| | - Gemma Reguera
- Department of Microbiology and Molecular Genetics, Michigan State University, 567 Wilson Rd, Rm 6190, Biomedical and Physical Science Building, East Lansing, MI, 48823, USA.
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31
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Korth B, Kretzschmar J, Bartz M, Kuchenbuch A, Harnisch F. Determining incremental coulombic efficiency and physiological parameters of early stage Geobacter spp. enrichment biofilms. PLoS One 2020; 15:e0234077. [PMID: 32559199 PMCID: PMC7304624 DOI: 10.1371/journal.pone.0234077] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Accepted: 05/18/2020] [Indexed: 01/06/2023] Open
Abstract
Geobacter spp. enrichment biofilms were cultivated in batch using one-chamber and two-chamber bioelectrochemical reactors. Time-resolved substrate quantification was performed to derive physiological parameters as well as incremental coulombic efficiency (i.e., coulombic efficiency during one batch cycle, here every 6h) during early stage biofilm development. The results of one-chamber reactors revealed an intermediate acetate increase putatively due to the presence of acetogens. Total coulombic efficiencies of two-chamber reactors were considerable lower (19.6±8.3% and 49.3±13.2% for 1st and 2nd batch cycle, respectively) compared to usually reported values of mature Geobacter spp. enrichment biofilms presumably reflecting energetic requirements for biomass production (i.e., cells and extracellular polymeric substances) during early stages of biofilm development. The incremental coulombic efficiency exhibits considerable changes during batch cycles indicating shifts between phases of maximizing metabolic rates and maximizing biomass yield. Analysis based on Michaelis-Menten kinetics yielded maximum substrate uptake rates (vmax,Ac, vmax,I) and half-saturation concentration coefficients (KM,Ac,KM,I) based on acetate uptake or current production, respectively. The latter is usually reported in literature but neglects energy demands for biofilm growth and maintenance as well as acetate and electron storage. From 1st to 2nd batch cycle, vmax,Ac and KM,Ac, decreased from 0.0042-0.0051 mmol Ac- h-1 cm-2 to 0.0031-0.0037 mmol Ac- h-1 cm-2 and 1.02-2.61 mM Ac- to 0.28-0.42 mM Ac-, respectively. Furthermore, differences between KM,Ac/KM,I and vmax,Ac/vmax,I were observed providing insights into the physiology of Geobacter spp. enrichment biofilms. Notably, KM,I considerably scattered while vmax,Ac/vmax,I and KM,Ac remained rather stable indicating that acetate transport within biofilm only marginally affects reaction rates. The observed data variation mandates the requirement of a more detailed analysis with an improved experimental system, e.g., using flow conditions and a comparison with Geobacter spp. pure cultures.
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Affiliation(s)
- Benjamin Korth
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research—UFZ, Leipzig, Saxony, Germany
| | - Jörg Kretzschmar
- Biochemical Conversion Department, DBFZ Deutsches Biomasseforschungszentrum gemeinnützige GmbH, Leipzig, Saxony, Germany
| | - Manuel Bartz
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research—UFZ, Leipzig, Saxony, Germany
| | - Anne Kuchenbuch
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research—UFZ, Leipzig, Saxony, Germany
| | - Falk Harnisch
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research—UFZ, Leipzig, Saxony, Germany
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32
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Zhang T, Shi XC, Ding R, Xu K, Tremblay PL. The hidden chemolithoautotrophic metabolism of Geobacter sulfurreducens uncovered by adaptation to formate. ISME JOURNAL 2020; 14:2078-2089. [PMID: 32398660 DOI: 10.1038/s41396-020-0673-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 04/24/2020] [Accepted: 04/29/2020] [Indexed: 02/01/2023]
Abstract
Multiple Fe(III)-reducing Geobacter species including the model Geobacter sulfurreducens are thought to be incapable of carbon dioxide fixation. The discovery of the reversed oxidative tricarboxylic acid cycle (roTCA) for CO2 reduction with citrate synthase as key enzyme raises the possibility that G. sulfurreducens harbors the metabolic potential for chemolithoautotrophic growth. We investigate this hypothesis by transferring G. sulfurreducens PCA serially with Fe(III) as electron acceptor and formate as electron donor and carbon source. The evolved strain T17-3 grew chemolithoautotrophically with a 2.7-fold population increase over 48 h and a Fe(III) reduction rate of 417.5 μM h-1. T17-3 also grew with CO2 as carbon source. Mutations in T17-3 and enzymatic assays point to an adaptation process where the succinyl-CoA synthetase, which is inactive in the wild-type, became active to complete the roTCA cycle. Deletion of the genes coding for the succinyl-CoA synthetase in T17-3 prevented growth with formate as substrate. Enzymatic assays also showed that the citrate synthase can perform the necessary cleavage of citrate for the functional roTCA cycle. These results demonstrate that G. sulfurreducens after adaptation reduced CO2 via the roTCA cycle. This previously hidden metabolism can be harnessed for biotechnological applications and suggests hidden ecological functions for Geobacter.
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Affiliation(s)
- Tian Zhang
- State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan, 430070, PR China. .,School of Materials Science and Engineering, Wuhan University of Technology, Wuhan, 430070, PR China. .,School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan, 430070, PR China.
| | - Xiao-Chen Shi
- State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan, 430070, PR China.,School of Materials Science and Engineering, Wuhan University of Technology, Wuhan, 430070, PR China.,School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan, 430070, PR China
| | - Ran Ding
- State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan, 430070, PR China.,School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan, 430070, PR China
| | - Kai Xu
- Center for Material Research and Analysis, Wuhan University of Technology, Wuhan, 430070, PR China
| | - Pier-Luc Tremblay
- State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan, 430070, PR China. .,School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan, 430070, PR China.
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33
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Kubannek F, Thiel S, Bunk B, Huber K, Overmann J, Krewer U, Biedendieck R, Jahn D. Performance Modelling of the Bioelectrochemical Glycerol Oxidation by a Co‐Culture of
Geobacter Sulfurreducens
and
Raoultella Electrica. ChemElectroChem 2020. [DOI: 10.1002/celc.202000027] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Fabian Kubannek
- Institute of Energy and Process Systems EngineeringTechnische Universität Braunschweig Franz-Liszt-Straße 35 38106 Braunschweig Germany
| | - Simone Thiel
- Institute of Microbiology Braunschweig Integrated Centre of Systems Biology (BRICS)Technische Universität Braunschweig Rebenring 56 38106 Braunschweig Germany
| | - Boyke Bunk
- Leibniz Institute DSMZ-German Collection of MicroorganismsCell Cultures GmbH Inhoffenstraße 7B 38124 Braunschweig Germany
| | - Katharina Huber
- Leibniz Institute DSMZ-German Collection of MicroorganismsCell Cultures GmbH Inhoffenstraße 7B 38124 Braunschweig Germany
| | - Jörg Overmann
- Leibniz Institute DSMZ-German Collection of MicroorganismsCell Cultures GmbH Inhoffenstraße 7B 38124 Braunschweig Germany
| | - Ulrike Krewer
- Institute of Energy and Process Systems EngineeringTechnische Universität Braunschweig Franz-Liszt-Straße 35 38106 Braunschweig Germany
| | - Rebekka Biedendieck
- Institute of Microbiology Braunschweig Integrated Centre of Systems Biology (BRICS)Technische Universität Braunschweig Rebenring 56 38106 Braunschweig Germany
| | - Dieter Jahn
- Institute of Microbiology Braunschweig Integrated Centre of Systems Biology (BRICS)Technische Universität Braunschweig Rebenring 56 38106 Braunschweig Germany
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34
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Zhao F, Heidrich ES, Curtis TP, Dolfing J. The effect of anode potential on current production from complex substrates in bioelectrochemical systems: a case study with glucose. Appl Microbiol Biotechnol 2020; 104:5133-5143. [PMID: 32248443 PMCID: PMC7228986 DOI: 10.1007/s00253-020-10547-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 02/07/2020] [Accepted: 03/15/2020] [Indexed: 11/28/2022]
Abstract
Anode potential can affect the degradation pathway of complex substrates in bioelectrochemical systems (BESs), thereby influencing current production and coulombic efficiency. However, the intricacies behind this interplay are poorly understood. This study used glucose as a model substrate to comprehensively investigate the effect of different anode potentials (− 150 mV, 0 mV and + 200 mV) on the relationship between current production, the electrogenic pathway and the abundance of the electrogenic microorganisms involved in batch mode fed BESs. Current production in glucose-acclimatized reactors was a function of the abundance of Geobacteraceae and of the availability of acetate and formate produced by glucose degradation. Current production was increased by high anode potentials during acclimation (0 mV and + 200 mV), likely due to more Geobacteraceae developing. However, this effect was much weaker than a stimulus from an artificial high acetate supply: acetate was the rate-limiting intermediate in these systems. The supply of acetate could not be influenced by anode potential; altering the flow regime, batch time and management of the upstream fermentation processes may be a greater engineering tool in BES. However, these findings suggest that if high current production is the focus, it will be extremely difficult to achieve success with complex waste streams such as domestic wastewater.
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Affiliation(s)
- Fei Zhao
- School of Engineering, Newcastle University, Newcastle-upon-Tyne, England, NE1 7RU, UK
| | - Elizabeth S Heidrich
- School of Engineering, Newcastle University, Newcastle-upon-Tyne, England, NE1 7RU, UK
| | - Thomas P Curtis
- School of Engineering, Newcastle University, Newcastle-upon-Tyne, England, NE1 7RU, UK
| | - Jan Dolfing
- School of Engineering, Newcastle University, Newcastle-upon-Tyne, England, NE1 7RU, UK.
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35
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Yang W, Chen S. Biomass-Derived Carbon for Electrode Fabrication in Microbial Fuel Cells: A Review. Ind Eng Chem Res 2020. [DOI: 10.1021/acs.iecr.0c00041] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Wei Yang
- State Key Laboratory of Hydraulics and Mountain River Engineering, College of Water Resource & Hydropower, Sichuan University, Chengdu 610065, China
| | - Shaowei Chen
- Department of Chemistry and Biochemistry, University of California, 1156 High Street, Santa Cruz, California 95064, United States
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Flores-Rodriguez C, Min B. Enrichment of specific microbial communities by optimum applied voltages for enhanced methane production by microbial electrosynthesis in anaerobic digestion. BIORESOURCE TECHNOLOGY 2020; 300:122624. [PMID: 31918296 DOI: 10.1016/j.biortech.2019.122624] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 12/10/2019] [Accepted: 12/12/2019] [Indexed: 06/10/2023]
Abstract
This study investigates the distribution of microbiome in microbial electrosynthesis systems at different applied voltages (0.5, 1.0, and 1.5 V) for methane production. Results revealed that more favorable conditions for methane production were observed with 1.0 V applied voltage. In Venn plots, the bioelectrodes at 1.0 V had higher numbers of unique operational taxonomic units compared to those at 0.5 and 1.5 V. Hierarchical cluster, non-metric multidimensional scaling, and principal component ordinate analyses revealed that the biocathode at 1.0 V clustered separately from the rest of the biofilms mainly because of the quantitative differences in the microbial distribution. Taxonomically, exoelectrogens (Geobacter spp.) dominated the bioanode at 1.0 V, while the syntrophic assemblages of hydrogen-producing bacteria (i.e., Bacteroidetes and Firmicutes) and hydrogen-consuming methanogens (i.e., Methanobacterium sp.) existed in the biocathode. These results suggest that the optimum applied voltage enriched specific microbial communities on the anode and cathode for enhanced methane production.
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Affiliation(s)
- Carla Flores-Rodriguez
- Department of Environmental Science and Engineering, Kyung Hee University, Seocheon-dong, Yongin-si, Gyeonggi-do 446-701, Republic of Korea
| | - Booki Min
- Department of Environmental Science and Engineering, Kyung Hee University, Seocheon-dong, Yongin-si, Gyeonggi-do 446-701, Republic of Korea.
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A three-dimensional hybrid electrode with electroactive microbes for efficient electrogenesis and chemical synthesis. Proc Natl Acad Sci U S A 2020; 117:5074-5080. [PMID: 32051251 PMCID: PMC7060665 DOI: 10.1073/pnas.1913463117] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Addressing the global challenge of sustainability calls for cost-effective and eco-friendly pathways to go beyond the existing energy-intense synthetic routes. Biohybrid electrochemical systems integrate electroactive bacteria with synthetic electrodes to leverage the power of biocatalysis for energy conversion and chemical synthesis. This work presents a three-dimensional electrode scaffold to couple the intracellular metabolism with extracellular redox transformations by means of electrochemistry. The large population of bacteria actively metabolizing within the electrode scaffold produces a benchmark current density. The biohybrid electrode can also carry out synthetic reactions within or beyond biochemical pathways driven by solar light. This hierarchical electrode provides a robust and versatile platform to wire bacteria’s intrinsic physiological functionalities with artificial electronics for sustainable energy conversion and chemical production. Integration of electroactive bacteria into electrodes combines strengths of intracellular biochemistry with electrochemistry for energy conversion and chemical synthesis. However, such biohybrid systems are often plagued with suboptimal electrodes, which limits the incorporation and productivity of the bacterial colony. Here, we show that an inverse opal-indium tin oxide electrode hosts a large population of current-producing Geobacter and attains a current density of 3 mA cm−2 stemming from bacterial respiration. Differential gene expression analysis revealed Geobacter’s transcriptional regulations to express more electron-relaying proteins when interfaced with electrodes. The electrode also allows coculturing with Shewanella for syntrophic electrogenesis, which grants the system additional flexibility in converting electron donors. The biohybrid electrode containing Geobacter can also catalyze the reduction of soluble fumarate and heterogenous graphene oxide, with electrons from an external power source or an irradiated photoanode. This biohybrid electrode represents a platform to employ live cells for sustainable power generation and biosynthesis.
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Li J, Liu F, Yang C, Zheng S, Xiao L, Li J, Tu C, Luo Y. Inhibition effect of polyvinyl chloride on ferrihydrite reduction and electrochemical activities of Geobacter metallireducens. J Basic Microbiol 2019; 60:37-46. [DOI: 10.1002/jobm.201900415] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2019] [Revised: 10/10/2019] [Accepted: 10/18/2019] [Indexed: 11/10/2022]
Affiliation(s)
- Jiajia Li
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research; Chinese Academy of Sciences; Yantai China
- Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research; Chinese Academy of Sciences; Yantai China
- University of Chinese Academy of Sciences; Beijing China
| | - Fanghua Liu
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research; Chinese Academy of Sciences; Yantai China
- Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research; Chinese Academy of Sciences; Yantai China
| | - Cuiyun Yang
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research; Chinese Academy of Sciences; Yantai China
| | - Shiling Zheng
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research; Chinese Academy of Sciences; Yantai China
| | - Leilei Xiao
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research; Chinese Academy of Sciences; Yantai China
| | - Jinhua Li
- Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Institutions of Earth Science; Chinese Academy of Sciences; Beijing China
| | - Chen Tu
- Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research; Chinese Academy of Sciences; Yantai China
| | - Yongming Luo
- Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research; Chinese Academy of Sciences; Yantai China
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Semenec L, Vergara IA, Laloo AE, Mathews ER, Bond PL, Franks AE. Enhanced Growth of Pilin-Deficient Geobacter sulfurreducens Mutants in Carbon Poor and Electron Donor Limiting Conditions. MICROBIAL ECOLOGY 2019; 78:618-630. [PMID: 30759269 DOI: 10.1007/s00248-019-01316-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 01/01/2019] [Indexed: 06/09/2023]
Abstract
Geobacter sulfurreducens pili enable extracellular electron transfer and play a role in secretion of c-type cytochromes such as OmcZ. PilA-deficient mutants of G. sulfurreducens have previously been shown to accumulate cytochromes within their membranes. This cytochrome retaining phenotype allowed for enhanced growth of PilA-deficient mutants in electron donor and carbon-limited conditions where formate and fumarate are provided as the sole electron donor and acceptor with no supplementary carbon source. Conversely, wild-type G. sulfurreducens, which has normal secretion of cytochromes, has comparative limited growth in these conditions. This growth is further impeded for OmcZ-deficient and OmcS-deficient mutants. A PilB-deficient mutant which prevents pilin production but allows for secretion of OmcZ had moderate growth in these conditions, indicating a role for cytochrome localization to enabling survival in the electron donor and carbon-limited conditions. To determine which pathways enhanced growth using formate, Sequential Window Acquisition of all Theoretical Mass Spectra mass spectrometry (SWATH-MS) proteomics of formate adapted PilA-deficient mutants and acetate grown wild type was performed. PilA-deficient mutants had an overall decrease in tricarboxylic acid (TCA) cycle enzymes and significant upregulation of electron transport chain associated proteins including many c-type cytochromes and [NiFe]-hydrogenases. Whole genome sequencing of the mutants shows strong convergent evolution and emergence of genetic subpopulations during adaptation to growth on formate. The results described here suggest a role for membrane constrained c-type cytochromes to the enhancement of survival and growth in electron donor and carbon-limited conditions.
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Affiliation(s)
- Lucie Semenec
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Melbourne, Victoria, Australia
| | - Ismael A Vergara
- Bioinformatics and Cancer Genomics, Research Division, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - Andrew E Laloo
- Advanced Water Management Centre, The University of Queensland, Brisbane, Queensland, Australia
| | - Elizabeth R Mathews
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Melbourne, Victoria, Australia
| | - Philip L Bond
- Advanced Water Management Centre, The University of Queensland, Brisbane, Queensland, Australia
| | - Ashley E Franks
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Melbourne, Victoria, Australia.
- Centre for Future Landscapes, La Trobe University, Melbourne, Australia.
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Abstract
The family Geobacteraceae, with its only valid genus Geobacter, comprises deltaproteobacteria ubiquitous in soil, sediments, and subsurface environments where metal reduction is an active process. Research for almost three decades has provided novel insights into environmental processes and biogeochemical reactions not previously known to be carried out by microorganisms. At the heart of the environmental roles played by Geobacter bacteria is their ability to integrate redox pathways and regulatory checkpoints that maximize growth efficiency with electron donors derived from the decomposition of organic matter while respiring metal oxides, particularly the often abundant oxides of ferric iron. This metabolic specialization is complemented by versatile metabolic reactions, respiratory chains, and sensory networks that allow specific members to adaptively respond to environmental cues to integrate organic and inorganic contaminants in their oxidative and reductive metabolism, respectively. Thus, Geobacteraceae are important members of the microbial communities that degrade hydrocarbon contaminants under iron-reducing conditions and that contribute, directly or indirectly, to the reduction of radionuclides, toxic metals, and oxidized species of nitrogen. Their ability to produce conductive pili as nanowires for discharging respiratory electrons to solid-phase electron acceptors and radionuclides, or for wiring cells in current-harvesting biofilms highlights the unique physiological traits that make these organisms attractive biological platforms for bioremediation, bioenergy, and bioelectronics application. Here we review some of the most notable physiological features described in Geobacter species since the first model representatives were recovered in pure culture. We provide a historical account of the environmental research that has set the foundation for numerous physiological studies and the laboratory tools that had provided novel insights into the role of Geobacter in the functioning of microbial communities from pristine and contaminated environments. We pay particular attention to latest research, both basic and applied, that has served to expand the field into new directions and to advance interdisciplinary knowledge. The electrifying physiology of Geobacter, it seems, is alive and well 30 years on.
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41
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Reguera G. Microbial nanowires and electroactive biofilms. FEMS Microbiol Ecol 2019; 94:5000162. [PMID: 29931163 DOI: 10.1093/femsec/fiy086] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 05/11/2018] [Indexed: 12/14/2022] Open
Abstract
Geobacter bacteria are the only microorganisms known to produce conductive appendages or pili to electronically connect cells to extracellular electron acceptors such as iron oxide minerals and uranium. The conductive pili also promote cell-cell aggregation and the formation of electroactive biofilms. The hallmark of these electroactive biofilms is electronic heterogeneity, mediated by coordinated interactions between the conductive pili and matrix-associated cytochromes. Collectively, the matrix-associated electron carriers discharge respiratory electrons from cells in multilayered biofilms to electron-accepting surfaces such as iron oxide coatings and electrodes poised at a metabolically oxidizable potential. The presence of pilus nanowires in the electroactive biofilms also promotes the immobilization and reduction of soluble metals, even when present at toxic concentrations. This review summarizes current knowledge about the composition of the electroactive biofilm matrix and the mechanisms that allow the wired Geobacter biofilms to generate electrical currents and participate in metal redox transformations.
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Affiliation(s)
- Gemma Reguera
- Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA
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42
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Dantas JM, Portela PC, Fernandes AP, Londer YY, Yang X, Duke NEC, Schiffer M, Pokkuluri PR, Salgueiro CA. Structural and Functional Relevance of the Conserved Residue V13 in the Triheme Cytochrome PpcA from Geobacter sulfurreducens. J Phys Chem B 2019; 123:3050-3060. [PMID: 30875222 DOI: 10.1021/acs.jpcb.9b01214] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The triheme cytochrome PpcA from Geobacter sulfurreducens is highly abundant under several growth conditions and is important for extracellular electron transfer. PpcA plays a central role in transferring electrons resulting from the cytoplasmic oxidation of carbon compounds to the cell exterior. This cytochrome is designed to couple electron and proton transfer at physiological pH, a process achieved via the selection of dominant microstates during the redox cycle of the protein, which are ultimately regulated by a well-established order of oxidation of the heme groups. The three hemes are covered only by a polypeptide chain of 71 residues and are located in the small hydrophobic core of the protein. In this work, we used NMR and X-ray crystallography to investigate the structural and functional role of a conserved valine residue (V13) located within van der Waals contact of hemes III and IV. The residue was replaced by alanine (V13A), isoleucine (V13I), serine (V13S), and threonine (V13T) to probe the effects of the side chain volume and polarity. All mutants were found to be as equally thermally stable as the native protein. The V13A and V13T mutants produced crystals and their structures were determined. The side chain of the threonine residue introduced in V13T showed two conformations, but otherwise the two structures did not show significant changes from the native structure. Analysis of the redox behavior of the four mutants showed that for the hydrophobic replacements (V13A and V13I) the redox properties, and hence the order of oxidation of the hemes, were unaffected in spite of the larger side chain, isoleucine, showing two conformations with minor changes of the protein in the heme core. On the other hand, the polar replacements (V13S and V13T) showed the presence of two more distinctive conformations, and the oxidation order of the hemes was altered. Overall, it is striking that a single residue with proper size and polarity, V13, was naturally selected to ensure a unique conformation of the protein and the order of oxidation of the hemes, endowing the cytochrome PpcA with the optimal functional properties necessary to ensure effectiveness in the extracellular electron transfer respiratory pathways of G. sulfurreducens.
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Affiliation(s)
- Joana M Dantas
- UCIBIO-Requimte, Departamento de Química , Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa , Campus Caparica, 2829-516 Caparica , Portugal
| | - Pilar C Portela
- UCIBIO-Requimte, Departamento de Química , Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa , Campus Caparica, 2829-516 Caparica , Portugal
| | - Ana P Fernandes
- UCIBIO-Requimte, Departamento de Química , Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa , Campus Caparica, 2829-516 Caparica , Portugal
| | - Yuri Y Londer
- Biosciences Division , Argonne National Laboratory , 9700 South Cass Avenue , Argonne , Illinois 60439 , United States
| | - Xiaojing Yang
- Biosciences Division , Argonne National Laboratory , 9700 South Cass Avenue , Argonne , Illinois 60439 , United States
| | - Norma E C Duke
- Biosciences Division , Argonne National Laboratory , 9700 South Cass Avenue , Argonne , Illinois 60439 , United States
| | - Marianne Schiffer
- Biosciences Division , Argonne National Laboratory , 9700 South Cass Avenue , Argonne , Illinois 60439 , United States
| | - P Raj Pokkuluri
- Biosciences Division , Argonne National Laboratory , 9700 South Cass Avenue , Argonne , Illinois 60439 , United States
| | - Carlos A Salgueiro
- UCIBIO-Requimte, Departamento de Química , Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa , Campus Caparica, 2829-516 Caparica , Portugal
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Engel C, Schattenberg F, Dohnt K, Schröder U, Müller S, Krull R. Long-Term Behavior of Defined Mixed Cultures of Geobacter sulfurreducens and Shewanella oneidensis in Bioelectrochemical Systems. Front Bioeng Biotechnol 2019; 7:60. [PMID: 30972336 PMCID: PMC6445848 DOI: 10.3389/fbioe.2019.00060] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Accepted: 03/05/2019] [Indexed: 11/24/2022] Open
Abstract
This work aims to investigate the long-term behavior of interactions of electrochemically active bacteria in bioelectrochemical systems. The electrochemical performance and biofilm characteristics of pure cultures of Geobacter sulfurreducens and Shewanella oneidensis are being compared to a defined mixed culture of both organisms. While S. oneidensis pure cultures did not form cohesive and stable biofilms on graphite anodes and only yielded 0.034 ± 0.011 mA/cm2 as maximum current density by feeding of each 5 mM lactate and acetate, G. sulfurreducens pure cultures formed 69 μm thick, area-wide biofilms with 10 mM acetate as initial substrate concentration and yielded a current of 0.39 ± 0.09 mA/cm2. Compared to the latter, a defined mixed culture of both species was able to yield 38% higher maximum current densities of 0.54 ± 0.07 mA/cm2 with each 5 mM lactate and acetate. This increase in current density was associated with a likewise increased thickness of the anodic biofilm to approximately 93 μm. It was further investigated whether a sessile incorporation of S. oneidensis into the mixed culture biofilm, which has been reported previously for short-term experiments, is long-term stable. The results demonstrate that S. oneidensis was not stably incorporated into the biofilm; rather, the planktonic presence of S. oneidensis has a positive effect on the biofilm growth of G. sulfurreducens and thus on current production.
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Affiliation(s)
- Christina Engel
- Institute of Biochemical Engineering, Technische Universität Braunschweig, Braunschweig, Germany.,Braunschweig Centre of Systems Biology (BRICS), Technische Universität Braunschweig, Braunschweig, Germany
| | - Florian Schattenberg
- Working Group Flow Cytometry, Department of Environmental Microbiology, Centre for Environmental Research - UFZ, Leipzig, Germany
| | - Katrin Dohnt
- Institute of Biochemical Engineering, Technische Universität Braunschweig, Braunschweig, Germany.,Braunschweig Centre of Systems Biology (BRICS), Technische Universität Braunschweig, Braunschweig, Germany
| | - Uwe Schröder
- Braunschweig Centre of Systems Biology (BRICS), Technische Universität Braunschweig, Braunschweig, Germany.,Institute of Environmental and Sustainable Chemistry, Technische Universität Braunschweig, Braunschweig, Germany
| | - Susann Müller
- Working Group Flow Cytometry, Department of Environmental Microbiology, Centre for Environmental Research - UFZ, Leipzig, Germany
| | - Rainer Krull
- Institute of Biochemical Engineering, Technische Universität Braunschweig, Braunschweig, Germany.,Braunschweig Centre of Systems Biology (BRICS), Technische Universität Braunschweig, Braunschweig, Germany
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Zhang X, Prévoteau A, Louro RO, Paquete CM, Rabaey K. Periodic polarization of electroactive biofilms increases current density and charge carriers concentration while modifying biofilm structure. Biosens Bioelectron 2018; 121:183-191. [DOI: 10.1016/j.bios.2018.08.045] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 08/19/2018] [Accepted: 08/20/2018] [Indexed: 10/28/2022]
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Microbial anodic consortia fed with fermentable substrates in microbial electrolysis cells: Significance of microbial structures. Bioelectrochemistry 2018; 123:219-226. [DOI: 10.1016/j.bioelechem.2018.05.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Revised: 05/16/2018] [Accepted: 05/19/2018] [Indexed: 11/22/2022]
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46
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Cai X, Huang L, Yang G, Yu Z, Wen J, Zhou S. Transcriptomic, Proteomic, and Bioelectrochemical Characterization of an Exoelectrogen Geobacter soli Grown With Different Electron Acceptors. Front Microbiol 2018; 9:1075. [PMID: 29963016 PMCID: PMC6013743 DOI: 10.3389/fmicb.2018.01075] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Accepted: 05/07/2018] [Indexed: 01/10/2023] Open
Abstract
The ability of Geobacter species to transfer electrons outside cells enables them to play an important role in biogeochemical and bioenergy processes. Our knowledge of the extracellular electron transfer (EET) process in the genus Geobacter is mainly from the study of G. sulfurreducens, and in order to fully investigate the EET mechanisms in the genus Geobacter, other Geobacter species should also be considered. This study focused on the EET of Geobacter soli GSS01, which exhibited a capability of reducing insoluble Fe(III) oxides and generating electrical current comparable with G. sulfurreducens PCA. Electrochemical characterization, including cyclic voltammetry, differential pulse voltammetry, and electrochemical in situ FTIR spectra, revealed that different redox proteins contributed to the electrochemical behaviors of G. soli and G. sulfurreducens. Based on comparative transcriptomic and proteomic analyses, OmcS was the most upregulated protein in both G. soli and G. sulfurreducens cells grown with insoluble Fe(III) oxides vs. soluble electron acceptor. However, the proteins including OmcE and PilA that were previously reported as being important for EET in G. sulfurreducens were downregulated or unchanged in G. soli cells grown with insoluble electron acceptors vs. soluble electron acceptor, and many proteins that were upregulated in G. soli cells grown with insoluble electron acceptors vs. soluble electron acceptor, such as OmcN, are not important for EET in G. sulfurreducens. We also identified 30 differentially expressed small RNAs (sRNAs) in G. soli cells grown with different acceptors. Taken together, these findings help to understand the versatile EET mechanisms that exist in the genus Geobacter and point to the possibility of sRNA in modulating EET gene expression.
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Affiliation(s)
- Xixi Cai
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Lingyan Huang
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Guiqin Yang
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Zhen Yu
- Guangdong Key Laboratory of Integrated Agro-Environmental Pollution Control and Management, Guangdong Institute of Eco-Environmental Science and Technology, Guangzhou, China
| | - Junlin Wen
- Guangdong Key Laboratory of Integrated Agro-Environmental Pollution Control and Management, Guangdong Institute of Eco-Environmental Science and Technology, Guangzhou, China
| | - Shungui Zhou
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
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Kiamco MM, Mohamed A, Reardon PN, Marean-Reardon CL, Aframehr WM, Call DR, Beyenal H, Renslow RS. Structural and metabolic responses of Staphylococcus aureus biofilms to hyperosmotic and antibiotic stress. Biotechnol Bioeng 2018; 115:1594-1603. [PMID: 29460278 PMCID: PMC5959008 DOI: 10.1002/bit.26572] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 01/10/2018] [Accepted: 02/08/2018] [Indexed: 01/26/2023]
Abstract
Biofilms alter their metabolism in response to environmental stress. This study explores the effect of a hyperosmotic agent-antibiotic treatment on the metabolism of Staphylococcus aureus biofilms through the use of nuclear magnetic resonance (NMR) techniques. To determine the metabolic activity of S. aureus, we quantified the concentrations of metabolites in spent medium using high-resolution NMR spectroscopy. Biofilm porosity, thickness, biovolume, and relative diffusion coefficient depth profiles were obtained using NMR microimaging. Dissolved oxygen concentration was measured to determine the availability of oxygen within the biofilm. Under vancomycin-only treatment, the biofilm communities switched to fermentation under anaerobic condition, as evidenced by high concentrations of formate (7.4 ± 2.7 mM), acetate (13.1 ± 0.9 mM), and lactate (3.0 ± 0.8 mM), and there was no detectable dissolved oxygen in the biofilm. In addition, we observed the highest consumption of pyruvate (0.19 mM remaining from an initial 40 mM concentration), the sole carbon source, under the vancomycin-only treatment. On the other hand, relative effective diffusion coefficients increased from 0.73 ± 0.08 to 0.88 ± 0.08 under vancomycin-only treatment but decreased from 0.71 ± 0.04 to 0.60 ± 0.07 under maltodextrin-only and from 0.73 ± 0.06 to 0.56 ± 0.08 under combined treatments. There was an increase in biovolume, from 2.5 ± 1 mm3 to 7 ± 1 mm3 , under the vancomycin-only treatment, while the maltodextrin-only and combined treatments showed no significant change in biovolume over time. This indicated that physical biofilm growth was halted during maltodextrin-only and combined treatments.
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Affiliation(s)
- Mia M Kiamco
- The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, Washington
| | - Abdelrhman Mohamed
- The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, Washington
| | - Patrick N Reardon
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington
| | - Carrie L Marean-Reardon
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington
| | - Wrya M Aframehr
- The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, Washington
| | - Douglas R Call
- Paul G. Allen School for Global Animal Health, Washington State University, Pullman, Washington
| | - Haluk Beyenal
- The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, Washington
| | - Ryan S Renslow
- The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, Washington
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington
- Earth and Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington
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Reguera G. Harnessing the power of microbial nanowires. Microb Biotechnol 2018; 11:979-994. [PMID: 29806247 PMCID: PMC6201914 DOI: 10.1111/1751-7915.13280] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Revised: 04/13/2018] [Accepted: 04/22/2018] [Indexed: 12/13/2022] Open
Abstract
The reduction of iron oxide minerals and uranium in model metal reducers in the genus Geobacter is mediated by conductive pili composed primarily of a structurally divergent pilin peptide that is otherwise recognized, processed and assembled in the inner membrane by a conserved Type IVa pilus apparatus. Electronic coupling among the peptides is promoted upon assembly, allowing the discharge of respiratory electrons at rates that greatly exceed the rates of cellular respiration. Harnessing the unique properties of these conductive appendages and their peptide building blocks in metal bioremediation will require understanding of how the pilins assemble to form a protein nanowire with specialized sites for metal immobilization. Also important are insights into how cells assemble the pili to make an electroactive matrix and grow on electrodes as biofilms that harvest electrical currents from the oxidation of waste organic substrates. Genetic engineering shows promise to modulate the properties of the peptide building blocks, protein nanowires and current‐harvesting biofilms for various applications. This minireview discusses what is known about the pilus material properties and reactions they catalyse and how this information can be harnessed in nanotechnology, bioremediation and bioenergy applications.
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Affiliation(s)
- Gemma Reguera
- Department of Microbiology and Molecular Genetics, Michigan State University, 567 Wilson Rd., Rm. 6190, East Lansing, MI, 48824, USA
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Tejedor-Sanz S, Fernández-Labrador P, Hart S, Torres CI, Esteve-Núñez A. Geobacter Dominates the Inner Layers of a Stratified Biofilm on a Fluidized Anode During Brewery Wastewater Treatment. Front Microbiol 2018; 9:378. [PMID: 29568284 PMCID: PMC5853052 DOI: 10.3389/fmicb.2018.00378] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 02/20/2018] [Indexed: 12/14/2022] Open
Abstract
In this study, we designed a microbial electrochemical fluidized bed reactor (ME-FBR), with an electroconductive anodic bed made of activated carbon particles for treating a brewery wastewater. Under a batch operating mode, acetate and propionate consumption rates were 13-fold and 2.4-fold higher, respectively, when the fluidized anode was polarized (0.2 V) with respect to open circuit conditions. Operating in a continuous mode, this system could effectively treat the brewery effluent at organic loading rates (OLR) over 1.7 kg m-3NRV d-1 and with removal efficiencies of 95 ± 1.4% (hydraulic retention time of 1 day and an influent of 1.7 g-COD L-1). The coulombic efficiency values highly depended upon the OLR applied, and varied from a 56 ± 15% to 10 ± 1%. Fluorescence in situ hybridization (FISH) analysis revealed a relative high abundance of Geobacter species (ca. 20%), and clearly showed a natural microbial stratification. Interestingly, the Geobacter cluster was highly enriched in the innermost layers of the biofilm (thickness of 10 μm), which were in contact with the electroconductive particles of bed, whereas the rest of bacteria were located in the outermost layers. To our knowledge, this is the first time that such a clear microbial stratification has been observed on an anode-respiring biofilm. Our results revealed the relevant role of Geobacter in switching between the electrode and other microbial communities performing metabolic reactions in the outermost environment of the biofilm.
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Affiliation(s)
- Sara Tejedor-Sanz
- Department of Chemical Engineering, University of Alcalá, Alcalá de Henares, Spain.,IMDEA Water Institute, Alcalá de Henares, Spain
| | - Patricia Fernández-Labrador
- Department of Chemical Engineering, University of Alcalá, Alcalá de Henares, Spain.,Mahou San Miguel, Madrid, Spain
| | - Steven Hart
- Biodesign Swette Center for Environmental Biotechnology, Arizona State University, Tempe, AZ, United States
| | - Cesar I Torres
- Biodesign Swette Center for Environmental Biotechnology, Arizona State University, Tempe, AZ, United States.,School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ, United States
| | - Abraham Esteve-Núñez
- Department of Chemical Engineering, University of Alcalá, Alcalá de Henares, Spain.,IMDEA Water Institute, Alcalá de Henares, Spain
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Kretzschmar J, Böhme P, Liebetrau J, Mertig M, Harnisch F. Microbial Electrochemical Sensors for Anaerobic Digestion Process Control - Performance of Electroactive Biofilms under Real Conditions. Chem Eng Technol 2018. [DOI: 10.1002/ceat.201700539] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Jörg Kretzschmar
- DBFZ Deutsches Biomasseforschungszentrum gemeinnützige GmbH; Biochemical Conversion Department; Torgauer Strasse 116 04347 Leipzig Germany
| | - Paul Böhme
- DBFZ Deutsches Biomasseforschungszentrum gemeinnützige GmbH; Biochemical Conversion Department; Torgauer Strasse 116 04347 Leipzig Germany
| | - Jan Liebetrau
- DBFZ Deutsches Biomasseforschungszentrum gemeinnützige GmbH; Biochemical Conversion Department; Torgauer Strasse 116 04347 Leipzig Germany
| | - Michael Mertig
- Kurt-Schwabe-Institut für Mess- und Sensortechnik e.V. Meinsberg (KSI); Kurt-Schwabe-Strasse 4 04720 Waldheim Germany
- Technical University Dresden; Physical Chemistry, Measurement and Sensor Technology; Eisenstuckstrasse 5 01069 Dresden Germany
| | - Falk Harnisch
- Helmholtz-Centre for Environmental Research GmbH - UFZ; Department Environmental Microbiology; Permoserstrasse 15 04318 Leipzig Germany
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