Unit of Environmental Biotechnology and GIS, Department of Advanced Zoology and Biotechnology/LIFE, Loyola College, Chennai 600 034, India.
Saudi J Biol Sci. 2011 Apr;18(2):157-67. doi: 10.1016/j.sjbs.2010.12.003. Epub 2010 Dec 17.
Detoxification of Cr(VI) under alkaline pH requires attention due to the alkaline nature of many effluents. An alkaliphilic gram-positive Bacillus subtilis isolated from tannery effluent contaminated soil was found to grow and reduce Cr(VI) up to 100% at an alkaline pH 9. Decrease in pH to acidic range with growth of the bacterium signified the role played by metabolites (organic acids) in chromium resistance and reduction mechanism. The XPS and FT-IR spectra confirmed the reduction of Cr(VI) by bacteria into +3 oxidation state. Chromate reductase assay indicated that the reduction was mediated by constitutive membrane bound enzymes. The kinetics of Cr(VI) reduction activity derived using the monod equation proved (K s = 0.00032) high affinity of the organism to the metal. This study thus helped to localize the reduction activity at subcellular level in a chromium resistant alkaliphilic Bacillus sp.
由于许多废水呈碱性,因此需要注意在碱性 pH 下对 Cr(VI) 进行解毒。从制革厂废水污染的土壤中分离出的一株嗜碱性革兰氏阳性枯草芽孢杆菌被发现能够在碱性 pH 9 下生长并将 Cr(VI)还原高达 100%。随着细菌的生长,pH 值下降到酸性范围表明代谢物(有机酸)在铬抗性和还原机制中发挥了作用。XPS 和 FT-IR 光谱证实了细菌将 Cr(VI)还原为+3 氧化态。铬酸盐还原酶测定表明,还原是由组成型膜结合酶介导的。使用 Monod 方程得出的 Cr(VI)还原活性动力学表明,该生物体对金属具有高亲和力(K s = 0.00032)。因此,这项研究有助于在耐铬嗜碱性芽孢杆菌中定位亚细胞水平的还原活性。