China
Africa
Explore chapters and articles related to this topic
Electrochemically Assisted Artificial Wetlands, Generating Electricity From Wastewater Treatment
Published in María del Carmen Durán-Domínguez-de-Bazúa, Amado Enrique Navarro-Frómeta, Josep M. Bayona, Artificial or Constructed Wetlands, 2018
María Guadalupe Salinas-Juárez
Among the microorganisms found in MFC are: Shewanella putrefaciens, Geobacteraceae sulfurreducens, Geobacter multireducens, pseudomonas, acidobacteria, proteobacteria a, p, and 8, as well as firmicutes (Kim et al. 2008; Logan and Regan 2006). The species considered as electrochemically active belong to the Geobacter and Shewanella species, being both iron-reducing bacteria; the family Geobacteraceae, especially, can transfer electrons directly to the anode. However, distinct microbial consortium participation, just like the respective metabolic pathways, are necessary to efficiently convert the stored energy from organic matter into electricity (Kim et al. 2008; Logan et al. 2006; Lu et al. 2015). Hence, the results are more promising when using a mixed culture for the inoculum than a pure culture due to the synergistic interactions among microorganisms which benefit power generation, despite the microorganisms involved be unknown.
*
Published in Ozcan Konur, Bioenergy and Biofuels, 2017
Microbial communities developed in the bioanode utilizing biomass-derived substrates are expected to contain fermentative as well as exoelectrogenic microbes at a minimum. In addition, degraders of specific substrates such as furanic and phenolic compounds are likely to be present. The microbial community reported by Lewis et al. (2015) is shown in Figure 16.12 a and b. It included Proteobacteria as the dominant phylum, and Geobacteraceae, Clostridiaceae, Rhodocyclaceae, Enterococcaceae, and Sphingobacteriaceae, plus a few other unique families are in the consortia. The primary role of the Geobacteraceae can be predicted to be exoelectrogenesis; however, the function of most other members is difficult to predict without further investigations. Several other members have known exoelectrogens in the family as well, including Enterococcaceae, Rhodocyclaeceae, and Comamonadaceae; however, these members could also play fermentative or other roles in the community. The community developed using model furanic and phenolic substrates as reported by Zeng et al. (2015) is shown in Figure 16.12c. This community is slightly different than the one reported using BOAP as substrate at the phylum level; however, there were differences at the family and genus level. The 16S rRNA-based identification has limitations and deeper genomic information is needed to distinguish between the functional capacities of the communities.
Advances in electrochemically active bacteria: Physiology and ecology
Published in Maximilian Lackner, Philipp Stadler, Wilhelm Grabow, Handbook of Online and Near-real-time Methods in Microbiology, 2017
A.C. Marques, L. Santos, J.M. Dantas, A. Gonçalves, S. Casaleiro, R. Martins, C.A. Salgueiro, E. Fortunato
Geobacteraceae are among the few well-studied, pure-culture, metalreducing that are able to transfer electrons to electrode surfaces (Bond et al. 2002, Bond and Lovley 2003, Lovley 2008). Most of what is mechanistically known about Geobacter, EET processes is derived from pure-culture studies with the model representative, G. sulfurreducens. This was the first Geobacter species for which methods for genetic manipulation were developed, making it the choice for functional genomic studies designed to understand Geobacter metabolism, gene regulation and EET (Lovley et al. 2011). Gene knock-out studies on strains of G. sulfurreducens carrying deletions in genes encoding outer membrane c-type cytochromes (e.g., OmcB, OmcS and OmcE), known to be required for optimal electron transfer to metal oxides, did not show a direct correspondence with current production (Borole et al. 2011). Cytochome OmcS was proposed to be involved in a direct contact mechanism based on the partial defect in current production of an OmcS-OmcT double mutant. Cell monolayers of G. sulfurreducens were immobilized on electrode surfaces and characterized electrochemically to demonstrate a direct-contact mechanism (Marsili et al. 2008, Srikanth et al. 2008). Despite repeated washes to remove the loosely-bound outer membrane c-type cytochromes, such as OmcS, the cells were still able to interface electronically with the electrode surface (Srikanth et al. 2008). Thus, a minimum set of redox-active molecules was present in the cells that enabled direct and immediate transfer of electrons from the cell to the electrode. The abundancy of the outer membrane c-type cytochromes in this microorganism suggests that the pathway may not be specific. Hence, the quantity and diversity of cytochromes, rather than the presence of specific types, may enable cells to attach to the electrode surface and strategically position the redox centers in close proximity to the electrode surface for promoting optimal tunneling rates (Borole et al. 2011).
A review of design, operational conditions and applications of microbial fuel cells
Published in Biofuels, 2018
Rachna Goswami, Vijay Kumar Mishra
Geobacter is a genus of proteobacteria. Geobacter are anaerobic respiration bacterial species and found to be the first organism with the skill to oxidize organic compounds and metals, including iron, radioactive metals and petroleum compounds, into environmentally benign carbon dioxide while using iron oxide or other available metals as electron acceptor [82]. Bond and Lovley [69] used Geobacter sulfurreducens in MFC chambers, graphite electrode as the sole electron acceptor, and acetate or hydrogen as the electron donor. Holmes et al. [52] studied the potential role of Geobacteraceae, Geopsychrobacter electrodiphilus gen. nov., sp. nov., in electricity generation through a marine sediment fuel cell. Two unique marine isolates were found, strains A1T and A2. They are gram-negative, non-motile rods with copious c-type cytochromes. Phylogenetic assessment of the 16S rRNA, recA, gyrB, fusA, rpoB and nifD genes inferred that strains A1T and A2 represented a distinctive phylogenetic cluster in the Geobacteraceae. Both strains were capable to grow with an electrode providing the sole electron acceptor. These organisms were the first psychrotolerant members of Geobacteraceae reported and grown at temperatures of 4–30◦C, with an optimal temperature of 22◦C. Marine sediment microorganisms were evaluated by Bond et al. to harvest energy [1]. A specific enrichment of microorganisms of the family Geobacteraceae on an energy harvesting anode displayed that these microorganisms conserved energy to sustain their growth by oxidizing organic compounds with an electrode helping as the sole electron acceptor. This was valuable in encouraging the bioremediation of organic contaminants in subsurface environments.