Geobacter genus

Bacteria included in Geobacter genus oxidize anaerobically organic compounds or inorganic compounds with ferric ion as a result ferric ion is reduced to ferrous ion. By the actions of the bacteria, various ores of iron, e.g., magnetite, are produced (Chaudhuri et al., 2001). 

A membrane-bound NADH-dependent ferric iron reductase has been obtained from Geobacter sulfurreducens (Magnuson et al., 2000). The enzyme contains a hemoprotein and FAD. the reduced hemoprotein in the enzyme is reoxidized on addition of ferric ion and NADH is a specific electron donor for the enzyme. The bacterium has a citric acid cycle (TCA cycle) (Galushko and Schink, 2000). Besides G. metallireducens and G. sulfurreducens, several bacteria of Geobacter genus have been isolated, namely G. bremensis, G. pelophilus (Straub and Buchholz-Cleven, 2001), G. hydrogenophilus, G. chapelli, and G. grbiciae (Coates et al., 2001). 

Multiheme cytochromes c play an important role in bacterial iron respiration. In this process, soluble Fe chelates or insoluble Fe oxides serve as terminal electron acceptors of the anaerobic respiratory chain. In Shewanella and Geobacter spp., the two most studied Fe -reducing organisms, a great increase in cellular multiheme c-type cytochromes is observed upon growth by iron respiration. In the case of the genus Shewanella, electron transport to Fe involves CymA in the cytoplasmic membrane, and several... 

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