期刊
JOURNAL OF HAZARDOUS MATERIALS
卷 367, 期 -, 页码 215-223出版社
ELSEVIER
DOI: 10.1016/j.jhazmat.2018.12.038
关键词
Chromium; Coalmine; Stress response; Reduction mechanism; Bioremediation
资金
- CSIR, Government of India [38(1410)/15/EMR-II]
- WB-DST, Government of West-Bengal, India [ST/P/ST/5G-18/2017]
- CSIR [38(1410)/15/EMR-II]
Microbial reduction of Cr(VI) to Cr(III) can mitigate environmental chromium toxicity. A chromium, cadmium and nickel tolerating strain TCL with 97% 16S rRNA gene sequence homology to Bacillus cereus was isolated from a derelict open-cast, Tasra Coalmine Lake of Jharia, India. It could tolerate up to Cr-2000 [2,000 mg L-1 Cr(VI)] and completely reduce Cr-200 within 16 h under heterotrophic condition. TCL grown in >= Cr-500 exhibited multifarious stress responses particularly in its prolonged lag-phase, like cell aggregation, up to two-fold elongation, increased exopolysaccharide production, and stress enzyme activities. These were relieved by increasing inoculum size or nutrient content. Chromium reduction was constitutive, with maximum activities detected in loosely-bound exopolysaccharides and membrane fractions, followed by cytoplasm and spent media. Cr(VI) was efficiently reduced to Cr(III) and > 90% was released in spent media. Cells also expressed Cr-induced active efflux pumps. Growing cells or its crude enzyme extracts could efficiently reduce Cr(VI) in diverse temperatures (15-45 degrees C), pH (5-9); and in presence of other metals (Cd, Cu, Mo, Ni, Pb), oxyanions (SO4-2, NO2-), and metabolic inhibitors (phenol, NaN3, EDTA). Growth and reduction were also detected in nutrient-limited minimal salt media, and contaminated leather industry effluent thereby making TCL a potential candidate for bioremediation.
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