Domain: Bacteria; Phylum: Unknown; Class: Unknown; Order: Unknown; Family: Thermodesulfobacteriaceae
Genus species: Geothermobacterium ferrireducens
Description and Significance
G. ferrireducens is a novel species, and not much is known about the organism. There are many limitations to infer in physiology and likely biogeochemical reactions in hydrothermal vents. It's habitat is the obsidian pools in Yellowstone National Park where the bacterium was first isolated from. It's a hyperthermophile and an anaerobe.
The bacterium is gram negative and is rod shaped. It's 1.0-1.2µm in length and 0.5µm in diameter as shown in figure 1 . It's motile by means of monotrichous flagellation. The number of chromosomes is unknown. An interesting feature is it's optimal temperature is between 85-90ºC, which is the highest temperature of any bacterial organism .
Cell Structure, Metabolism and Life Cycle
The cells are seen as single cells or in pairs of cells. G. ferrireducens does not use organic carbon as an energy source. The cell surface can have poor crystalline iron oxide, which is a dense material, attached to it. It gains energy by reducing Fe (III).
The ability to use Fe(III) as a terminal electron acceptor is a highly conserved characteristic in hyperthermophilic microorganisms. Further studies that use Fe(III) as an electron acceptor in pure cultures may be able to recover other uncultured hyperthermophiles. Ultimately, there is still some physiological and biochemical data that is unknown about G. ferrireducens and therefore a great deal of research must be further conducted.
Ecology and Pathogenesis
There is no symbiosis found thus far. Studies have elucidated 16S rDNA sequences from hydrothermal vents to be more closely related to the 16S rDNA sequence of strain FW-1a, rather than T. commune or T.hveragerdense . This relationship is important, because findings that once suggested microorganisms to be capable of sulfate reduction. However, microorganisms may not have the capacity for sulfate reduction or heterotrophic metabolism, but rather autotrophic hydrogen oxidizing Fe(III)-reducing microorganisms, with a physiology more similar to that of strain FW-1a. These results illustrate there are still limitations to inferring physiology as well as biogeochemical reactions in hydrothermal environments based on the analysis of 16S rDNA sequence .
There is no evidence of this bacterium causing any forms of disease.
 Kashefi, Kazem, Holmes, Dawn E., Reysenbach, Anna-Louise, and Lovley, Derek R.. “Use of Fe(III) as an Electron Acceptor To Recover Previously Uncultured Hyperthermophiles: Isolation and Characterization of Geothermobacterium ferrireducens gen. nov., sp. nov.” Applied and Environmental Microbiology 68.4 (2002): 1735-1742. PubMed Central. Web. 13 Apr. 2014.
Page authored by Katy Matson and Janessa Esquible, student of Prof. Edward Walker and Kazem Kashefi at Michigan State University.