Geopsychrobacter electrodiphilus'

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Classification

Bacteria; Thermodesulfobacteria; Desulfuromonadia; Disulfuromonadales; Geopsychrobacteraceae

Description and Significance

Name Geo "from surface", psychro "psychrotolerant", bacter "rod-shaped", electrodi "found on electrode", philus "loving" Found in the Boston Harbor, Massachusetts on an electrode of a sediment feul cell about 5 meters deep. Psychrotolerant because they are found in temperatures between 4 degrees and 30 degrees celsius. This species is especially interesting because they can transfer electrons from oxidizing organic compounds. They are rod shaped, gram negative, and nonmotile.

Genome Structure

The genome consists of one chromosome. They found that the 16S rRNA most similar to Malonomonas Rubra. When comparing sequences between recA, gyrB, fusA, rpoB, and nifD genes from known Geobacteraceae it was discovered that the recA, gyrB, and nifD genes from strains A1 and A2 are most similar to those of Desulfuromonas palmitatis, while the fusA and rpoB genes are most similar to those of Desulfuromusa succinoxidans. Their studies indicated that 65% of the 16S rRNA sequences associated with the current-harvesting electrodes in marine sediment fuel cellsare 90 to 97% similar to the 16S rRNA sequences of G. electrodiphilus.

Cell Structure, Metabolism and Life Cycle

In an anaerobic environment, in this case, the sediment feul cell, some microbes digest complex organic matter near a graphite electrode. On the surface of this graphite elctrode, G. electrodiphilus grows and oxidizes fermentation products like acetate. As oxidation processes are coupled with reduction reactions, those oxidation processes produce carbon dioxide, protons and electrons. Poorly crystallized iron(III) oxide (that would be reduced to magnetite) could be used as a terminal electron acceptor, but in a sediment fuel cell, G. electrodiphilus has direct contact to the electrode and can use it as a sole electron acceptor. The electrons flow from the anode to the cathode in the overlying aerobic water, where they reduce oxygen.

Ecology and Pathogenesis

G. electrodiphilus is found in sludge. In areas where sulfuphate reducers can thrive, G. electrodiphilus population decreased. In Blood Falls, Antarctica, an investigation of bacterial diversity of an iron oxide-tainted section of saltwater found that about 11% of microbes were G. electrodiphilus. The saltwater was identified as a subglacial ocean, where coupled biogeochemical processes below the glacier enable microbes to grow in extended isolation, accumulating iron(II) despite the presence of an active sulfur cycle.

References

Schoch CL, et al. NCBI Taxonomy: a comprehensive update on curation, resources and tools. Database (Oxford). 2020: baaa062. PubMed: 32761142 PMC: PMC7408187.

Holmes DE, Nicoll JS, Bond DR, Lovley DR (October 2004). "Potential role of a novel psychrotolerant member of the family Geobacteraceae, Geopsychrobacter electrodiphilus gen. nov., sp. nov., in electricity production by a marine sediment fuel cell". Applied and Environmental Microbiology. 70 (10): 6023–30. Bibcode:2004ApEnM..70.6023H. doi:10.1128/AEM.70.10.6023-6030.2004. PMC 522133. PMID 15466546.

Ow YP, Green DR, Hao Z, Mak TW. Cytochrome c: functions beyond respiration. Nat Rev Mol Cell Biol. 2008 Jul;9(7):532-42. doi: 10.1038/nrm2434. PMID: 18568041.

Author

Page authored by Michele Renard, student of Prof. Bradley Tolar at UNC Wilmington.