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A low‐GC Gram‐positive Thermoanaerobacter ‐like bacterium isolated from an Indian hot spring contains Cr(VI) reduction activity both in the membrane and cytoplasm
Author(s) -
Bhowmick D.C.,
Bal B.,
Chatterjee N.S.,
Ghosh A.N.,
Pal S.
Publication year - 2009
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1111/j.1365-2672.2009.04159.x
Subject(s) - thermophile , bioremediation , bacteria , cytoplasm , biology , biochemistry , 16s ribosomal rna , microbiology and biotechnology , cell fractionation , hot spring , chemistry , membrane , gene , genetics , paleontology
Aim: Characterization of an anaerobic thermophilic bacterium and subcellular localization of its Cr(VI)‐reducing activity for potential bioremediation applications. Methods and Results: 16S rRNA gene sequence‐based analyses of bacterial strains isolated from sediment samples of a Bakreshwar (India) hot spring, enriched anaerobically in iron‐reducing medium, found them to be 86–96% similar to reported Thermoanaerobacter strains. The most efficient iron reducer among these, BSB‐33, could also reduce Cr(VI) at an optimum temperature of 60°C and pH 6·5. Filtered culture medium could reduce Cr(VI) but not Fe(III). Cell‐free extracts reduced Cr(VI) inefficiently under aerobic conditions but efficiently anaerobically. Fractionation of the cell‐free extracts showed that chromium reduction activity was present in both the cytoplasm and membrane. Conclusions: BSB‐33 reduced Fe(III) and Cr(VI) anaerobically at 60°C optimally. After fractionation, the reducing activity of Cr(VI) was found in both cytoplasmic and membrane fractions. Significance and Impact of the Study: To the best of our knowledge, this is the first systematic study of anaerobic Cr(VI) reduction by a gram‐positive thermophilic micro‐organism and, in contrast to our results, none of the earlier reports has mentioned Cr(VI)‐reducing activity to be present both in the cytoplasm and membrane of an organism. The strain may offer itself as a potential candidate for bioremediation.