M Oves, MS Khan, E Ahmad, A Zaidi
Department of Agricultural Microbiology, Aligarh Muslim University, Aligarh, India.


A bacterial strain OS4 with high Cr(VI)-reducing ability under alkaline and acidic conditions was isolated from a polluted soil irrigated from Hindon river and identified as Stenotrophomonas maltophilia on the basis of 16S rRNA gene sequence analysis. The bacteria were rod shaped, Gram-negative and motile. The physiological and biochemical characteristics, and Cr(VI)-reduction of the strain were also studied. The results showed that the Stenotrophomonas maltophilia strain OS-4 was tolerant to very high concentration of Cr(VI) (1200 mg/L) and capable of reducing different forms of Cr(VI) (chromate and dichromate), under a wide range of temperatures (20-45◦C) and pH (5-11) with optimum at 35 ◦C and initial pH 9. Higher rates of Cr(VI)-reduction were observed with higher initial cell and Cr(VI) concentrations. Strain OS4 could reduce Cr(VI) very efficiently over a wide range of Cr(VI) concentrations (50-1000 mg/L). The addition of glucose caused a dramatic increase in Cr(VI)-reduction by Stenotrophomonas maltophilia strain OS-4. The presence of other metals, such as Cu, Co, Mn, etc., significantly stimulated Cr(VI)-reduction ability by the strain OS4. The results obtained in this study have importance for the bioremediation of chromate pollution. Read more…

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