Abstract
We have studied the reduction of hexavalent chromium (chromate) to the less toxic trivalent form by using cell suspensions and cell-free extracts from the common soil bacterium, Bacillus subtilis. B. subtilis was able to grow and reduce chromate at concentrations ranging from 0.1 to 1 mM K2CrO4. Chromate reduction was not affected by a 20-fold excess of nitrate-compound that serves as alternate electron acceptor and antagonizes chromate reduction by anaerobic bacteria. Metabolic poisons including sodium azide and sodium cyanide inhibited chromate reduction. Reduction was effected by a constitutive system associated with the soluble protein fraction and not with the membrane fraction. The reducing activity was heat labile and showed a Km of 188 μm CrO4 2-. The reductase can mediate the transfer of electrons from NAD(P)H to chromate. The results suggest that chromate is reduced via a detoxification system rather than dissimilatory electron transport.
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Garbisu, C., Alkorta, I., Llama, M.J. et al. Aerobic chromate reduction by Bacillus subtilis. Biodegradation 9, 133–141 (1998). https://doi.org/10.1023/A:1008358816529
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DOI: https://doi.org/10.1023/A:1008358816529