[Microbial reduction ability of various iron oxides in pure culture experiment]

The microbial reduction of ferrihydrite, lepidocrocite, hematite, goethite and aluminum-substituted iron oxides were examined by iron-reducer GS-15 under anaerobic pure culture condition. The results indicated that the ferrihydrite and lepidocrocite can be rapidly reduced by iron-reducer, and the percentage of microbial reduction are respectively 95.4% and 95.8% after 4 days incubation at 25 degrees C. The other iron oxides like hematite, Al-hematite, goethite and Al-goethite are very difficult to reduce during short-term incubation. The amounts of Fe(III)-reducing, Fe(II)-producing and Fe-reducing calculated by acetate consumption are identical under the conditions of lower concentration iron oxides addition.