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Final Edit of- "Geobacter"
History (Unchanged)
[edit]Geobacter metallireducens was first isolated by Derek Lovley in 1987 in sand sediment from the Potomac River in Washington D.C. The first strain was deemed strain GS-15.[1]
Metabolic Mechanisms (Newly Added)
[edit]For quite some time, it was thought that Geobacter species lacked c-cytochromes that can be utilized to reduce metal ions, hence it was assumed that they required direct physical contact in order to use metal ions as terminal electron acceptors (TEAs).[2] The discovery of the highly conductive pili in Geobacter species, and the proposal of using them as biological nano-wires further strengthened this view.[2] Nevertheless, recent discoveries have revealed that many Geobacter species, such as G. uraniireducens, not only do not possess highly conductive pili, but also do not need direct physical contact in order to utilize the metal ions as TEAs, suggesting that there is a great variety of extracellular electron transport mechanisms among the Geobacter species.[3] For example, one other way of transporting electrons is via a quinone-mediated electron shuttle, which is observed in Geobacter sulfurreducens.[4]
Another observed metabolic phenomenon is the cooperation between Geobacter species, in which several species cooperate in metabolizing a mixture of chemicals that neither could process alone. Provided with ethanol and sodium fumarate, G. metallireducens broke down the ethanol, generating an excess of electrons that were passed to G. sulfurreducens via "nanowires" grown between them, enabling G. sulfurreducens to break down the fumarate ions.[5] The nanowires are made of proteins with metal-like conductivity.[6]
Applications (Edited)
[edit]Biodegradation and bioremediation
[edit]Geobacter's ability to consume oil-based pollutants and radioactive material with carbon dioxide as waste byproduct has been used in environmental clean-up for underground petroleum spills and for the precipitation of uranium out of groundwater.[7][8] Geobacter degrade the material by creating electrically conductive pili between itself and the pollutant material, using it as an electron source.[9]
Microbial biodegradation of recalcitrant organic pollutants is of great environmental significance and involves intriguing novel biochemical reactions. In particular, hydrocarbons and halogenated compounds have long been doubted to be anaerobically degradable, but the isolation of hitherto unknown anaerobic hydrocarbon-degrading and reductively dehalogenating bacteria documented these processes in nature. Novel biochemical reactions were discovered, enabling the respective metabolic pathways, but progress in the molecular understanding of these bacteria was slowed by the absence of genetic systems for most of them. However, several complete genome sequences later became available for such bacteria. The genome of the hydrocarbon degrading and iron-reducing species G. metallireducens (accession nr. NC_007517) was determined in 2008. The genome revealed the presence of genes for reductive dehalogenases, suggesting a wide dehalogenating spectrum. Moreover, genome sequences provided insights into the evolution of reductive dehalogenation and differing strategies for niche adaptation.[10]
Vengeanceknight (talk) 22:34, 13 November 2017 (UTC)
- ^ Lovley DR, Stolz JF, Nord GL, Phillips, EJP (1987). "Anaerobic Production of Magnetite by a Dissimilatory Iron-Reducing Microorganism" (PDF). Nature. 350 (6145): 252–254. doi:10.1038/330252a0.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ a b Reguera, Gemma; McCarthy, Kevin D.; Mehta, Teena; Nicoll, Julie S.; Tuominen, Mark T.; Lovley, Derek R. (2005-06-23). "Extracellular electron transfer via microbial nanowires". Nature. 435 (7045): 1098–1101. doi:10.1038/nature03661. ISSN 1476-4687. PMID 15973408.
- ^ Tan, Yang; Adhikari, Ramesh Y.; Malvankar, Nikhil S.; Ward, Joy E.; Nevin, Kelly P.; Woodard, Trevor L.; Smith, Jessica A.; Snoeyenbos-West, Oona L.; Franks, Ashley E. (2016-06-28). "The Low Conductivity of Geobacter uraniireducens Pili Suggests a Diversity of Extracellular Electron Transfer Mechanisms in the Genus Geobacter". Frontiers in Microbiology. 7. doi:10.3389/fmicb.2016.00980. ISSN 1664-302X. PMC 4923279. PMID 27446021.
{{cite journal}}: CS1 maint: PMC format (link) CS1 maint: unflagged free DOI (link) - ^ Pat-Espadas, Aurora M.; Razo-Flores, Elías; Rangel-Mendez, J. Rene; Cervantes, Francisco J. "Direct and Quinone-Mediated Palladium Reduction byGeobacter sulfurreducens:Mechanisms and Modeling". Environmental Science & Technology. 48 (5): 2910–2919. doi:10.1021/es403968e.
- ^ Williams, Caroline (2011). "Who are you calling simple?". New Scientist. 211 (2821): 38–41. doi:10.1016/S0262-4079(11)61709-0.
- ^ Malvankar, Nikhil; Vargas, Madeline; Nevin, Kelly; Tremblay, Pier-Luc; Evans-Lutterodt, Kenneth; Nykypanchuk, Dmytro; Martz, Eric; Tuominen, Mark T; Lovley, Derek R (2015). "Structural Basis for Metallic-Like Conductivity in Microbial Nanowires". mBio. 6 (2).
- ^ "Stimulating the in situ activity of Geobacter species to remove uranium from the groundwater of a uranium-contaminated aquifer". Applied and Environmental Microbiology. 69 (10): 5884–91. 2003. doi:10.1128/aem.69.10.5884-5891.2003. PMC 201226. PMID 14532040.
{{cite journal}}: Unknown parameter|authors=ignored (help) - ^ Cologgi, Dena (2014). "Enhanced uranium immobilization and reduction by Geobacter sulfurreducens biofilms". Applied and Environmental Microbiology. 80 (21): 6638–6646. doi:10.1128/AEM.02289-14. PMC 4249037. PMID 25128347.
- ^ "Experiment and theory unite at last in debate over microbial nanowires". Phys.org. Retrieved 5 January 2016.
- ^ Heider J, Rabus R (2008). "Genomic Insights in the Anaerobic Biodegradation of Organic Pollutants". Microbial Biodegradation: Genomics and Molecular Biology. Caister Academic Press. ISBN 978-1-904455-17-2.
{{cite book}}: External link in|chapterurl=|chapterurl=ignored (|chapter-url=suggested) (help)