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Updated: Aug 19, 2026

Single-cell Analysis of Bacillus subtilis Biofilms Using Fluorescence Microscopy and Flow Cytometry
Published on: February 15, 2012
Aerobic chromate reduction by Bacillus subtilis
C Garbisu1, I Alkorta, M J Llama
1Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias, Universidad del País Vasco, Bilbao, Spain.
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 microns 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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