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Wu Y, Zhu X, Wang X, Lin Z, Reinfelder JR, Li F, Liu T. A New Electron Shuttling Pathway Mediated by Lipophilic Phenoxazine via the Interaction with Periplasmic and Inner Membrane Proteins of Shewanella oneidensis MR-1. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:2636-2646. [PMID: 36652548 DOI: 10.1021/acs.est.2c07862] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Although it has been established that electron mediators substantially promote extracellular electron transfer (EET), electron shuttling pathways are not fully understood. Here, a new electron shuttling pathway was found in the EET process by Shewanella oneidensis MR-1 with resazurin, a lipophilic electron mediator. With resazurin, the genes encoding outer-membrane cytochromes (mtrCBA and omcA) were downregulated. Although cytochrome deletion substantially reduced biocurrent generation to 1-12% of that of wild-type (WT) cells, the presence of resazurin restored biocurrent generation to 168 μA·cm-2 (ΔmtrA/omcA/mtrC), nearly equivalent to that of WT cells (194 μA·cm-2), indicating that resazurin-mediated electron transfer was not dependent on the Mtr pathway. Biocurrent generation by resazurin was much lower in ΔcymA and ΔmtrA/omcA/mtrC/fccA/cctA mutants (4 and 6 μA·cm-2) than in WT cells, indicating a key role of FccA, CctA, and CymA in this process. The effectiveness of resazurin in EET of Mtr cytochrome mutants is also supported by cyclic voltammetry, resazurin reduction kinetics, and in situ c-type cytochrome spectroscopy results. The findings demonstrated that low molecular weight, lipophilic electron acceptors, such as phenoxazine and phenazine, may facilitate electron transfer directly from periplasmic and inner membrane proteins, thus providing new insight into the roles of exogenous electron mediators in electron shuttling in natural and engineered biogeochemical systems.
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Affiliation(s)
- Yundang Wu
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
| | - Xiao Zhu
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
- Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Xinxin Wang
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
- College of Materials and Energy, South China Agricultural University, Guangzhou 510642, China
| | - Zhixin Lin
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
| | - John R Reinfelder
- Department of Environmental Sciences, Rutgers University, New Brunswick, New Jersey 08901, United States
| | - Fangbai Li
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
| | - Tongxu Liu
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
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Zhu X, Dou F, Long M, Wang X, Liu W, Li F, Liu T, Wu Y. Electron shuttle-dependent biofilm formation and biocurrent generation: Concentration effects and mechanistic insights. Front Microbiol 2023; 14:1070800. [PMID: 36937307 PMCID: PMC10016380 DOI: 10.3389/fmicb.2023.1070800] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2022] [Accepted: 01/31/2023] [Indexed: 03/05/2023] Open
Abstract
Introduction Electron shuttles (ESs) play a key role in extracellular electron transfer (EET) in Shewanella oneidensis MR-1. However, the quantification relationship between ES concentration, biofilm formation, and biocurrent generation has not been clarified. Methods In this study, 9,10-anthraquinone-2-sulfonic acid (AQS)-mediated EET and biofilm formation were evaluated at different AQS concentrations in bioelectrochemical systems (BESs) with S. oneidensis MR-1. Results and discussion Both the biofilm biomass (9- to 17-fold) and biocurrent (21- to 80-fold) were substantially enhanced by exogenous AQS, suggesting the dual ability of AQS to promote both biofilm formation and electron shuttling. Nevertheless, biofilms barely grew without the addition of exogenous AQS, revealing that biofilm formation by S. oneidensis MR-1 is highly dependent on electron shuttling. The biofilm growth was delayed in a BES of 2,000 μM AQS, which is probably because the redundant AQS in the bulk solution acted as a soluble electron acceptor and delayed biofilm formation. In addition, the maximum biocurrent density in BESs with different concentrations of AQS was fitted to the Michaelis-Menten equation (R 2 = 0.97), demonstrating that microbial-catalyzed ES bio-reduction is the key limiting factor of the maximum biocurrent density in BESs. This study provided a fundamental understanding of ES-mediated EET, which could be beneficial for the enrichment of electroactive biofilms, the rapid start-up of microbial fuel cells (MFCs), and the design of BESs for wastewater treatment.
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Affiliation(s)
- Xiao Zhu
- Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangzhou, China
- Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Fei Dou
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangzhou, China
- Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou, China
| | - Mingliang Long
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangzhou, China
- Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou, China
- College of Materials and Energy, South China Agricultural University, Guangzhou, China
| | - Xinxin Wang
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangzhou, China
- Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou, China
- College of Materials and Energy, South China Agricultural University, Guangzhou, China
| | - Wei Liu
- College of Materials and Energy, South China Agricultural University, Guangzhou, China
| | - Fangbai Li
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangzhou, China
- Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou, China
| | - Tongxu Liu
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangzhou, China
- Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou, China
| | - Yundang Wu
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangzhou, China
- Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou, China
- *Correspondence: Yundang Wu
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Wang H, Qi X, Zhang L, Zhang X, Xu P, Wang X. Efficient bioelectricity generation and carbazole biodegradation using an electrochemically active bacterium Sphingobium yanoikuyae XLDN2-5. CHEMOSPHERE 2022; 307:135986. [PMID: 35970217 DOI: 10.1016/j.chemosphere.2022.135986] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 07/04/2022] [Accepted: 08/06/2022] [Indexed: 06/15/2023]
Abstract
Carbazole and its derivatives are polycyclic aromatic heterocycles with unusual toxicity and mutagenicity. However, disposal of these polycyclic aromatic heterocycles remains a significant challenge. This study focused on efficient resource recovery from carbazole using an obligate aerobe, Sphingobium yanoikuyae XLDN2-5, in microbial fuel cells (MFCs). S. yanoikuyae XLDN2-5 successfully achieved carbazole degradation and simultaneously electricity generation in MFCs with a maximum power density of 496.8 mW m-2 and carbazole degradation rate of 100%. It is the first time that S. yanoikuyae XLDN2-5 was discovered as an electrochemically active bacterium with high extracellular electron transfer (EET) capability. Redox mediator analysis indicated that no self-produced redox mediators were found for S. yanoikuyae XLDN2-5 under analysis conditions, and the exogenous redox mediators used in this study did not promote its EET. The nanowires produced by S. yanoikuyae XLDN2-5 cells were found in the biofilm by morphology characterization and the growth process of the nanowires was consistent with the discharge process of the MFC. Conductivity determination further verified that the nanowires produced by S. yanoikuyae XLDN2-5 cells were electrically conductive. Based on these results, it is speculated that S. yanoikuyae XLDN2-5 may mainly utilize conductive nanowires produced by itself rather than redox mediators to meet the requirements of normal energy metabolism when it grows in the low dissolved oxygen zone of the anodic biofilm. These novel findings on the EET mechanism of S. yanoikuyae XLDN2-5 lay a foundation for further exploration of polycyclic aromatic heterocyclic pollutants treatment in electrochemical devices, which may create new biotechnology processes for these pollutants control.
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Affiliation(s)
- Huimin Wang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, 266237, PR China; Department of Microbiology, College of Life Science, Key Laboratory for Agriculture Microbiology, Shandong Agricultural University, Taian, 271018, PR China
| | - Xiaoyan Qi
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, 266237, PR China
| | - Lei Zhang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, 266237, PR China
| | - Xueli Zhang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, 266237, PR China
| | - Ping Xu
- State Key Laboratory of Microbial Metabolism and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, PR China
| | - Xia Wang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, 266237, PR China.
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Lin Z, Long M, Liu W, Liu T, Li F, Wu Y. Distinct biofilm formation regulated by different culture media: Implications to electricity generation. Bioelectrochemistry 2021; 140:107826. [PMID: 33984692 DOI: 10.1016/j.bioelechem.2021.107826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 04/03/2021] [Accepted: 04/14/2021] [Indexed: 10/21/2022]
Abstract
Biofilm of Shewanella oneidensis MR-1 is extensively studied as it can transform organic compounds directly into electricity. Although revealing the biofilm regulation mechanism is crucial for enhancing bio-current, studies regarding the mechanism by which the culture condition affects biofilm formation are still lacking. The biofilm formation of S. oneidensis MR-1 in two typical media with same electron donor was investigated in this study. Bio-electricity increased 1.8 times in medium with phosphate-buffered saline (PBS) than in piperazine-1,4-bisethanesulfonic acid (PIPES). Biofilm total protein has 1.5-fold of difference between two media at day 3, and biofilm structures also differed; a fluffy biofilm with curled cells was formed in medium with PBS, whereas a compact, ordered, and closely attached biofilm was formed in medium with PIPES. Transcriptome studies clarified that the expression of genes beneficial for cell aggregation [e.g., aggA (2.3 fold), bpfA (2.8 fold) and csgB (3.9 fold)] in medium with PIPES was significantly upregulated, thus provided an explanation for the specific biofilm structure. Buffer concentration was proved to be a critical factor impacted cell morphology and current generation. The maximum current density in 30 mM of PBS and PIPES is 165 and 159 μA·cm-2 respectively, but it increased to 327 and 274 μA·cm-2 in 200 mM of PBS and PIPES. This study provides new insights into the mechanism of medium-dependent biofilm regulation, which will be beneficial for developing simple and efficient strategies to enhance bio-electricity generation.
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Affiliation(s)
- Zhixin Lin
- College of Materials and Energy, South China Agricultural University, Guangzhou 510642, China; Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
| | - Mingliang Long
- College of Materials and Energy, South China Agricultural University, Guangzhou 510642, China; Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
| | - Wei Liu
- College of Materials and Energy, South China Agricultural University, Guangzhou 510642, China.
| | - Tongxu Liu
- Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
| | - Fangbai Li
- Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China; National-Regional Joint Engineering ResearchCenter for Soil Pollution Control and Remediation in South China,Guangzhou 510650, China
| | - Yundang Wu
- Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China.
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