Expression Analysis of Geobacter sulfurreducens Current-Consuming Biofilm versus No-Current Biofilm
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ABSTRACT:
ORGANISM(S): Geobacter sulfurreducens
PROVIDER: GSE19149 | GEO | 2010/11/23
SECONDARY ACCESSION(S): PRJNA123751
REPOSITORIES: GEO
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Project description:There is a wide diversity of potential applications for direct electron transfer from electrodes to microorganisms, which might be better optimized if the mechanisms for this novel electrode-biofilm interaction were better understood. Geobacter sulfurreducens is one of the few microorganisms available in pure culture that is known to be capable of directly accepting electrons from a negatively poised electrode. A microarray comparison of cells accepting electrons from the electrode versus cells donating electrons to the electrode reveals that the genes previously observed to be upregulated in current-producing biofilms are not highly expressed in current-consuming biofilms.
2010-11-23 | GSE19150 | GEO
Project description:G. sulfurreducens can generate electricity from the oxidation of organic compounds. This is because it can take electrons from organic compounds and ship them out to the outer surface of the cell where they can then be deposited on various insoluble electron acceptors including electrodes. Cells attatched to the surface of an electrode oxidize acetate and and deposit the electrons derived from acetate onto the surface of the electrode after which they can travel through an electrical circuit, producing a current. Microbial fuel cells powered by acetate oxidation by Geobacter species are called Geobatteries. In this experiment we compared gene expression in a biofilm of the wild type strain growing on the surface of an electrode within a current-producing Geobattery to gene expression in a wild type biofilm that is not producing current, but is growing on the surface of an electrode. In both cases, the cells were growing in a flow-through two chambered H-cell Geobattery setup. This consists of two glass chambers, an anoxic anode chamber containing G. sulfurreducens, a graphite electrode, a reference electrode and growth medium and an oxic chamber containing the counter electrode. The two chambers are connected by a cation selective membrane and a wire connected to a potentionstat. A potentiostat is an instrument which maintains the redox potential of the anode at a fixed value relative to a reference electrode. Media continuously flowed through the anoxic anode chamber at a dilution rate of 0.15. In the experimental condition, the Geobattery was operational. The circuit was closed and G. sulfurreducens attached to the electrode generated current as it oxidized acetate. The redox potential at the anode was poised at 300 mV by the potentiostat. In the control condition, everything was the same, except that the medium in the anode chamber contained fumarate as electron acceptor, and the anode was not hooked up to the potentiostat i.e. the circuit was open. This prevented the anode from serving as an electron acceptor. Nevertheless a thick G. sulfurreducens biofilm grew on the surface of the electrode. The control and experimental geobatteries were harvested when current in the operational/experimental Geobatteries reached 10 mA. Keywords: two condition comparison
2009-06-03 | GSE8012 | GEO
Project description:The formation of electroactive biofilms is a crucial process for the generation of bioelectricity and bioremediation. G. sulfurreducens is a dissimilatory metal-reducing microorganism that can couple oxidation of organic matter with extracellular electron transfer to different insoluble electron acceptors. It has the capability to form biofilms in insoluble metal oxides and electroconductive biofilms in electrodes in bioelectrochemical systems. The formation of electroactive biofilms in this microorganism is a process that has been studied from a physiological, genetic, physical, and electrochemical approach. In G. sulfurreducens, we found that the transcriptional regulator GSU1771 participates in the gene expression of essential genes involved in electron transfer and biofilm formation. Strains deficient in GSU1771 increases Fe(III) reduction, produces more c-type cytochromes and exopolysaccharides. Furthermore, the biofilms produced are thicker and more electroactive than wild-type. In this work, we investigate the global gene expression profile performing RNA-seq comparing Δgsu1771 mutant biofilm grown in non-conductive support (glass) and respiring-graphite electrode. RNA-seq analysis of Δgsu1771 biofilm grown in glass support revealed a total of 467 (167 upregulated and 300 downregulated) differentially expressed genes versus the wild-type biofilm. Meanwhile, in Δgsu1771 biofilm developed in respiring-electrode graphite, we detect 119 (79 upregulated and 40 downregulated) differentially expressed genes with respect to wild-type biofilm. Moreover, transcriptional changes of 67 (56 with the same regulation and in 11 counterregulation) genes were shared in Δgsu1771 biofilm developed in glass and graphite electrodes. We locate upregulated in Δgsu1771 biofilms potential target genes, involved in exopolysaccharide synthesis (gsu1961-63, gsu1959, gsu1972-73, gsu1976-77). We confirmed the upregulation of gsu1979, gsu0972, gsu0783, pgcA, omcM, aroG, panC gnfK, gsu2507, and the downregulation of asnA, ato-1, gsu0810, pilA, csrA, ppcD, and gsu3356 genes by RT-qPCR. DNA-protein binding assay shows direct binding of the GSU1771 regulator to the promoter region of pgcA, pulF, relA, and gsu3356. Also, heme-staining and western blotting revealed an increase of c-type cytochromes in Δgsu1771 biofilms such as OmcS and OmcZ. In general, our data shows that GSU1771 is a global regulator involved in controlling the extracellular electron transfer and exopolysaccharide synthesis, processes required for electroconductive biofilm development.
2023-06-19 | GSE223184 | GEO
Project description:Anode-associated multi-species exoelectrogenic biofilms are essential to the function of bioelectrochemical systems (BESs). The investigation of electrode-associated biofilms is critical to advance understanding of the function of individual members within communities that thrive using an electrode as the terminal electron acceptor. This study focusses on the analysis of a model biofilm community consisting of Shewanella oneidensis, Geobacter sulfurreducens and Geobacter metallireducens. The conducted experiments revealed that the organisms can build a stable biofilm on an electrode surface that is rather resilient to changes in the redox potential of the anode surface. The community operated at maximum electron transfer rates with electrode potentials of 0.04 V versus normal hydrogen electrode. Current densities decreased gradually with lower potentials and reached half-maximal values at -0.08 V. A positive interaction of the individual strains could be observed in our experiments. At least S. oneidensis and G. sulfurreducens show an upregulation of their central metabolism as a response to cultivation under mixed-species conditions. Interestingly, G. sulfurreducens was detected in the planktonic phase of the bioelectrochemical reactors only in mixed-culture experiments but not when it was grown in the absence of the other two organisms. It is possible that G. sulfurreducens cells used flavins which were released by S. oneidensis cells as electron shuttles. This would allow the organism to broaden its environmental niche. To the best of our knowledge, this is the first study describing the dynamics of biofilm formation of a model exoelectrogenic community, the resilience of the biofilm, and the molecular responses towards mixed-species conditions.
2017-01-18 | GSE79750 | GEO
Project description:Geobacter sulfurreducens is a dissimilatory metal-reducing bacterium capable of forming thick electron-conducting biofilms on solid electrodes in the absence of alternative electron acceptors. The remarkable ability of such biofilms to transfer electrons, liberated from soluble organic electron donors, over long distances has attracted scientific interest as to the mechanism for this process, and technological interest for application to microbial fuel and electrolysis cells and sensors. Here, we employ comparative proteomics to identify key metabolic pathways involved in G. sulfurreducens respiration by planktonic cells versus electron-conducting biofilms, in an effort to elucidate long-range electron transfer mechanisms.
2018-02-16 | PXD002667 | Pride
Project description:Bioelectrochemical systems employing mixed microbial communities as biocatalysts are gaining importance as potential renewable energy, bioremediation, or biosensing devices. While we are beginning to understand how individual microorganism species interact with an electrode as electron donor, not much is known about the interactions between different microbial species in a community. Here, we compare the bioelectrochemical performance of Shewanella oneidensis in a pure-culture and in a co-culture with the homolactic acid fermenter Lactococcus lactis. While S. oneidensis alone can only use lactate as electron donor for current production, the co-culture is able to convert glucose into current with a similar coulombic efficiency of approximately 17%, respectively. With (electro)-chemical analysis and transcription profiling, we found that the BES performance and S. oneidensis physiology were not significantly different whether grown as a pure- or co-culture. These co-culture experiments represent a first step in understanding microbial interactions in BES communities with the goal to design complex microbial communities, which specifically convert target substrates into electricity. Further, for the first time, we elucidated S. oneidensis gene expression with an electrode as the only electron acceptor. The expression pattern confirms many previous studies regarding the enzymatic requirements for electrode respiration, and it generates new hypotheses on the functions of proteins, which are so far not known to be involved in electrode respiration. The BES was either operated with S. oneidensis alone, fed with lactate, or it was operated with S. oneidensis and L. lactis with glucose as primary substrate. The basic medium was a modified M4 medium containing 0.5 g/L yeast extract, 0.5 g/L trypton and 5 g/L glycerol phosphate, besides the commen M4 incredients. S. oneidensis oxidizes lactate to acetate and electrons in a BES - the latter generate a current at a graphite anode. The anode biofilm was harvested after about 4 weeks of continuous BES operation and subjected to total RNA extraction.
2010-12-01 | E-GEOD-20343 | biostudies-arrayexpress
Project description:Lysinibacillus varians GY32 is a filamentous bacteria that can generate electricity in microbial fuel cells. To find potential genes participating in the electron transfer to electrode of Lysinibacillus varians GY32, we compared the gene expression profiles of this bacteria with yeast extract as electron donor and two electron acceptors, i.e. oxygen and electrode in microbial fuel cells. The results showed that several cytochrome c genes might play specific roles in the extracellular electron transfer to electrode in this strain.
2021-01-29 | GSE165754 | GEO
Project description:Lysinibacillus varians GY32 is a filamentous bacteria that can generate electricity in microbial fuel cells. To find potential genes participating in the electron transfer to electrode of Lysinibacillus varians GY32, we compared the gene expression profiles of this bacteria with acetate as electron donor and two electron acceptors, i.e. oxygen and electrode in microbial fuel cells. The results showed that several cytochrome c genes might play specific roles in the extracellular electron transfer to electrode in this strain.
2021-01-29 | GSE165753 | GEO
Project description:G. sulfurreducens (ATCC #51573) was obtained from the laboratory culture collection of Dr. Derek Lovley. Cells were grown under strict anaerobic conditions at 23 °C in batch culture. Both control and experimental populations were grown with 10mM acetate as the electron donor while Fe(III) as 55 mM ferric citrate served as the electron acceptor for the control populations and graphite anodes as the electron acceptor for the experimental populations. Controls populations were harvested at a concentration of 30 mM Fe(II). Fuel cell power output was monitored by measuring the voltage across a known resistance in the fuel cell and experimental populations were harvested when current production reached a steady state of 0.6 milliamperes. Cells were harvested at log phase by centrifugation at 4 °C and the cell pellet was flash-frozen in liquid nitrogen and then stored at -80 °C prior to RNA extraction. Three cultures of control and experimental populations were collected. Each culture vessel was harvested and extracted for total RNA separately to produce three biological replicates for this experiment. Additional information regarding the fuel cell experimental set up and culture conditions for this experiment can be found in both the current reference and the following reference: Bond DR and Lovley DR. Electricity production by Geobacter sulfurreducens attached to electrodes. 2003. Applied and Environmental Microbiology 69: 1548-1555.
2007-07-02 | E-TIGR-5001 | biostudies-arrayexpress
Project description:G. sulfurreducens (ATCC #51573) was obtained from the laboratory culture collection of Dr. Derek Lovley. Cells were grown under strict anaerobic conditions at 23 �Â�°C in batch culture. Both control and experimental populations were grown with 10mM acetate as the electron donor while Fe(III) as 55 mM ferric citrate served as the electron acceptor for the control populations and graphite anodes as the electron acceptor for the experimental populations. Controls populations were harvested at a concentration of 30 mM Fe(II). Fuel cell power output was monitored by measuring the voltage across a known resistance in the fuel cell and experimental populations were harvested when current production reached a steady state of 0.6 milliamperes. Cells were harvested at log phase by centrifugation at 4 �Â�°C and the cell pellet was flash-frozen in liquid nitrogen and then stored at -80 �Â�°C prior to RNA extraction. Three cultures of control and experimental populations were collected. Each culture vessel was harvested and extracted for total RNA separately to produce three biological replicates for this experiment. Additional information regarding the fuel cell experimental set up and culture conditions for this experiment can be found in both the current reference and the following reference: Bond DR and Lovley DR. Electricity production by Geobacter sulfurreducens attached to electrodes. 2003. Applied and Environmental Microbiology 69: 1548-1555.
2006-01-26 | E-TIGR-83 | biostudies-arrayexpress