Higher order taxa
Bacteria; Proteobacteria; Delta Proteobacteria; Desulferomonadales; Geobacteraceae
Description and significance
Geobacter metallireducens is a rod shaped, gram negative, anaerobic bacteria and can be seen to have flagella and pili. The first G. metallireducens (initially known as strain GS-15) was first isolated from freshwater sediment, and was able to gain energy through dissimilatory reduction of iron, manganese, uranium and other metals. This organism was the first organism found to oxidize organic compounds to carbon dioxide with iron oxides as the electron acceptor (Lovely and Phillips 1988). G. metallireducens can also oxidize short chain fatty acids, alcohols, and monoaromatic compounds such as toluene and phenol using iron as its electron acceptor (Lovely et al 1993).
G. metallireducens contains genes for flagella synthesis. G. metallireducens was orginally thought to be immotile because they were grown in labs under ideal conditions where the bacteria had plenty of soluble metals. Synthesis for flagella do not initiate unless nutrient conditions are poor. Under conditions where soluble metals were replaced with iron oxide, G. metallireducens was seen to grow flagella and swim (Genome News Network 2002). G. metallireducens also contains genes that allow the bacteria the ability of chemotaxis. Together with the ability to perform chemotaxis and produce and use flagella, G. metallireducens has the ability to move towards metallic compounds or favorable environments where nutrient supply is favorable.
Cell structure and metabolism
G. metallireducens is chemotactic towards Fe(II) and Mn(II) and expresses flagella and pili only when grown on insoluble Fe(III) or Mn(IV) oxide (Childers et al 2002). These results suggest that G. metallireducens senses when soluble electron acceptors are depleted which then triggers the synthesis of the appropriate appendages allowing it to search for, and establish contact with, insoluble Fe(III) or Mn(IV) oxide.
G. metallireducens has been known to take part in bioremediation. In addition to using iron, the G. metallireducens uses metals such as plutonium and uranium to metabolize food. G. metallireducens consumes these radioactive elements and breaks down the contaminants. In the case of uranium, it changes the metal from a soluble to an insoluble form. The insoluble uranium drops out of the groundwater, thus decontaminating streams and drinking water. It remains in the soil and could then be extracted (Childer 2002). The use of an insoluble electron acceptor may explain why Geobacter species predominate over other Fe(III) oxide-reducing microorganisms in a wide variety of sedimentary environments.
Describe any interactions with other organisms (included eukaryotes), contributions to the environment, effect on environment, etc.
How does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.
Application to Biotechnology
Does this organism produce any useful compounds or enzymes? What are they and how are they used?
Enter summaries of the most recent research here--at least three required
Lovley DR and Phillips EJ. "Novel Mode of Microbial Energy Metabolism: Organic Carbon Oxidation Coupled to Dissimilatory Reduction of Iron or Manganese". Applied and Environmental Microbiology. 1988. Volume 54, No. 6, p. 1472-1480.
Lovley DR, Giovannoni SJ, White DC, Champine JE, Phillips EJ, Gorby YA,Goodwin S. "Geobacter metallireducens gen. nov. sp. nov., a microorganism capable of coupling the complete oxidation of organic compounds to the reduction of iron and other metals." Arch Microbiol. 1993. Volume 159. No.4. p. 336-344.
Edited by Christine Tang student of Rachel Larsen and Kit Pogliano