Toxicity of hexavalent chromium and its reduction by bacteria isolated from soil contaminated with tannery waste.
An Arthrobacter sp. and a Bacillus sp., isolated from a long-term tannery waste contaminated soil, were examined for their tolerance to hexavalent chromium [Cr(VI)] and their ability to reduce Cr(VI) to Cr(III), a detoxification process in cell suspensions and cell extracts. Both bacteria tolerated Cr(VI) at 100 mg/ml on a minimal salts agar medium supplemented with 0.5% glucose, but only Arthrobacter could grow in liquid medium at this concentration. Arthrobacter sp. could reduce Cr(VI) up to 50 microg/ml, while Bacillus sp. was not able to reduce Cr(VI) beyond 20 microg/ml. Arthrobacter sp. was distinctly superior to the Bacillus sp. in terms of their Cr(VI)-reducing ability and resistance to Cr(VI). Assays with permeabilized (treated with toluene or Triton X 100) cells and crude extracts demonstrated that the Cr(VI) reduction was mainly associated with the soluble protein fraction of the cell. Arthrobacter sp. has a great potential for bioremediation of Cr(VI)-containing waste.
Megharaj
M
M
CSIRO Land and Water, PMB 2, Glen Osmond, SA 5064, Australia.
Avudainayagam
S
S
Naidu
R
R
D001173:Arthrobacter / Q000187:drug effects / Q000254:growth & development / Q000302:isolation & purification / Q000378:metabolism*; D001407:Bacillus / Q000187:drug effects / Q000254:growth & development / Q000302:isolation & purification / Q000378:metabolism*; D001673:Biodegradation, Environmental; D002857:Chromium / Q000032:analysis / Q000378:metabolism* / Q000494:pharmacology*; D003470:Culture Media; D024881:Drug Resistance, Bacterial; D007220:Industrial Waste; D008826:Microbial Sensitivity Tests; D010084:Oxidation-Reduction; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000032:analysis / Q000378:metabolism / Q000494:pharmacology; D013633:Tanning
D003470:Culture Media; D007220:Industrial Waste; D012989:Soil Pollutants; D002857:Chromium; C074702:chromium hexavalent ion