Bacterial Reduction of Ferric Compounds

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). 

Around the hydrothermal vents in the deep sea, extremely thermophilic bacteria reside which have the optimal growth temperature at 100°C which participate in the reduction of several metals. For example, Pyrobaculum islandicum (Kashefi 

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