GSU1771 regulates extracellular electron transfer and electroactive biofilm formation in Geobacter sulfurreducens: Genetic and electrochemical characterization

Hernández-Eligio, Alberto; Huerta-Miranda, G.A.; Martínez-Bahena, Sergio; Castrejón-López, Dulce; Miranda-Hernández, M.; Juárez, Katy

doi:10.1016/j.bioelechem.2022.108101

Cited by 10 publications

(31 citation statements)

References 65 publications

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“…Given that the midpoint potentials of OmcZ and OmcS are −0.42 V (vs. Ag/AgCl) and − 0.41 V (vs. Ag/AgCl) respectively (Fricke et al, 2008 ; Inoue et al, 2010 ; Qian et al, 2011 ), GNW2 and GNW3 were expected to have midpoint potentials lower than that of the control strain, which was inconsistent with the present results. Therefore, these findings indicated a complex regulation of redox components in G. sulfurreducens as suggested in previous studies (Hernández‐Eligio et al, 2022 ; Park & Kim, 2011 ). In addition, reversible peaks near the top of the CV curves at approximately −0.30 V (vs. Ag/AgCl) were resolved in all the biofilms of the constructed strains.…”

Section: Resultssupporting

confidence: 86%

“…Up to date, several genetic strategies have been developed to engineer G. sulfurreducens for improving its EET efficiency and current production (Dantas et al, 2015 ; Hernández‐Eligio et al, 2022 ; Leang et al, 2013 ; Tan et al, 2017 ). All these studies indicated the importance of protein nanowires for the formation of thick conductive biofilms as emphasized in this study.…”

Section: Resultsmentioning

confidence: 99%

“…The EET efficiency of G. sulfurreducens could not be improved by replacing the endogenous e‐pili with the more conductive one from G. metallireducens (Tan et al, 2017 ). On the contrary, the G. sulfurreducens variants with greater abundance of e‐pili and c ‐type cytochromes have stronger capacity for current production in MFCs than the wild type (Hernández‐Eligio et al, 2022 ; Leang et al, 2013 ; Yi et al, 2009 ). These findings indicated that the abundance of nanowires may be critical for enhancing EET efficiency of G. sulfurreducens .…”

Section: Introductionmentioning

confidence: 99%

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Enhancing electrical outputs of the fuel cells with Geobacter sulferreducens by overexpressing nanowire proteins

Wang

Dong

et al. 2022

Microbial Biotechnology

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Protein nanowires are critical electroactive components for electron transfer of Geobacter sulfurreducens biofilm. To determine the applicability of the nanowire proteins in improving bioelectricity production, their genes including pilA, omcZ, omcS and omcT were overexpressed in G. sulfurreducens.The voltage outputs of the constructed strains were higher than that of the control strain with the empty vector (0.470-0.578 vs. 0.355 V) in microbial fuel cells (MFCs). As a result, the power density of the constructed strains (i.e. 1.39-1.58 W m −2 ) also increased by 2.62-to 2.97-fold as compared to that of the control strain. Overexpression of nanowire proteins also improved biofilm formation on electrodes with increased protein amount and thickness of biofilms. The normalized power outputs of the constructed strains were 0.18-0.20 W g −1 that increased by 74% to 93% from that of the control strain.Bioelectrochemical analyses further revealed that the biofilms and MFCs with the constructed strains had stronger electroactivity and smaller internal resistance, respectively. Collectively, these results demonstrate for the first time that overexpression of nanowire proteins increases the biomass and electroactivity of anode-attached microbial biofilms. Moreover, this study provides a new way for enhancing the electrical outputs of MFCs. TA B L E 1 Bacterial strains and plasmids used in this study Strains or plasmids Relevant genotype or uses Source or reference Bacterial strains G. sulferreducens PCA Wild-type G. sulferreducens Liu et al. (2015) Control strain G. sulferreducens PCA containing empty pAWP78 vector This study GNW1 G. sulferreducens PCA containing pOEpilA This study GNW2 G. sulferreducens PCA containing pOEomcZ This study GNW3 G. sulferreducens PCA containing pOEomcS This study GNW4 G. sulferreducens PCA containing pOEomcT This study

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Section: Resultssupporting

confidence: 86%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Enhancing electrical outputs of the fuel cells with Geobacter sulferreducens by overexpressing nanowire proteins

Wang

Dong

et al. 2022

Microbial Biotechnology

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“…Moreover, efforts to understand the regulatory mechanisms governing electron transfer in Geobacter are needed. A recent study found that the Δgsu1771 mutant strain overexpresses pilA, c-type cytochromes, and develops thicker biofilms (Hernández-Eligio et al, 2022 ). This led to more efficient Fe(III) oxide reduction and approximately 100-fold higher current production in electrochemical reactors with fluorine-doped tin oxide electrodes.…”

Section: Electron Transfer Mechanisms Between Microbes and Surfacesmentioning

confidence: 99%

Electroactive biofilms: how microbial electron transfer enables bioelectrochemical applications

Conners

Karthikeyan

Bose

2022

Journal of Industrial Microbiology and Biotechnology

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Microbial biofilms are ubiquitous. In marine and freshwater ecosystems, microbe-mineral interactions sustain biogeochemical cycles, while biofilms found on plants and animals can range from pathogens to commensals. Moreover, biofouling and biocorrosion represent significant challenges to industry. Bioprocessing is an opportunity to take advantage of biofilms and harness their utility as chassis for biocommodity production. Electrochemical bioreactors have numerous potential applications, including wastewater treatment and commodity production. The literature examining these applications has demonstrated that the cell-surface interface is vital to facilitating these processes. Therefore, it is necessary to understand the state of knowledge regarding biofilms’ role in bioprocessing. This mini-review discusses bacterial biofilm formation, cell-surface redox interactions, and the role of microbial electron transfer in bioprocesses. It also highlights some current goals and challenges with respect to microbe-mediated bioprocessing and future perspectives.

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“…The resulting Δgsu1771 strain not only exhibited higher rates of soluble and insoluble Fe(III) reduction than the wild-type strain but also overexpresses pilA and the c-type cytochromes omcB, omcE, omcS, and omcZ. Additionally, the Δgsu1771 strain produces a thicker biofilm with higher exopolysaccharide production than the wild-type strain (Hernández-Eligio et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

Global transcriptional analysis ofGeobacter sulfurreducens gsu1771mutant biofilm grown on two different support structures

Jaramillo-Rodríguez

Vega‐Alvarado²,

Rodríguez-Torres

et al. 2023

Preprint

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Electroactive biofilms formation by the metal-reducing bacteriumGeobacter sulfurreducensis a crucial for bioelectricity generation and bioremediation. The transcriptional regulator GSU1771 controls the expression of essential genes involved in electron transfer and biofilm formation inG. sulfurreducens, with GSU1771-deficient producing thicker and more electroactive biofilms. Here, RNA-seq analyses were conducted to compare the global gene expression patterns of wild-type and Δgsu1771mutant biofilms grown on non-conductive (glass) and conductive (graphite electrode) materials. The Δgsu1771biofilm grown on the glass surface exhibited 467 differentially expressed (DE) genes (167 upregulated and 300 downregulated) versus the wild-type biofilm. In contrast, the Δgsu1771biofilm grown on the graphite electrode exhibited 119 DE genes (79 upregulated and 40 downregulated) versus the wild-type biofilm. Among these DE genes, 67 were also differentially expressed in the Δgsu1771biofilm grown on glass (56 with the same regulation and 11 exhibiting counter-regulation). Among the upregulated genes in the Δgsu1771biofilms, we identified potential target genes involved in exopolysaccharide synthesis (gsu1961-63,gsu1959,gsu1972-73,gsu1976-77). RT-qPCR analyses were then conducted to confirm the differential expression of a selection of genes of interest. DNA-protein binding assays demonstrated the direct binding of the GSU1771 regulator to the promoter region ofpgcA,pulF,relA, andgsu3356. Furthermore, heme-staining and western blotting revealed an increase inc-type cytochromes including OmcS and OmcZ in Δgsu1771biofilms. Collectively, our findings demonstrated that GSU1771 is a global regulator that controls extracellular electron transfer and exopolysaccharide synthesis inG. sulfurreducens, which is crucial for electroconductive biofilm development.ImportanceBiofilm formation is a multi-stage process that is finely coordinated by signal transduction and complex gene regulation mechanisms. Given the importance of biofilms and their biotechnological applications, understanding these processes inG. sulfurreducensis of great significance. Here, we studied the transcriptional profile of the Δgsu1771strain biofilms formed on two different supporting materials: (1) glass, a non-conductive surface and (2) a graphite electrode-based microbial fuel cell (MFC), which enabled us to assess the transcriptional responses of this strain during current production. By analyzing these two conditions, our study elucidated genes of interest that could be essential for biofilm production and extracellular electron transfer (EET) and provides new insights into the mechanisms that control these complex processes inG. sulfurreducens.

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GSU1771 regulates extracellular electron transfer and electroactive biofilm formation in Geobacter sulfurreducens: Genetic and electrochemical characterization

Cited by 10 publications

References 65 publications

Enhancing electrical outputs of the fuel cells with Geobacter sulferreducens by overexpressing nanowire proteins

Enhancing electrical outputs of the fuel cells with Geobacter sulferreducens by overexpressing nanowire proteins

Electroactive biofilms: how microbial electron transfer enables bioelectrochemical applications

Global transcriptional analysis ofGeobacter sulfurreducens gsu1771mutant biofilm grown on two different support structures

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