Isolation and characterization of heavy-metal resistant microbes from Industrial soil
R. A. Ansari1, A. A. Qureshi2* & D. S. Ramteke1
1Environmental Impact and Risk Assessment Division, 2Environmental Genomics Division, National Environmental Engineering Research Institute (NEERI), CSIR, Nehru Marg,
Contamination by heavy metals in soil is one of the major environmental problems in many countries and these contaminants reach from various sources such as vehicles and other industrial activities. Soil samples were collected from industrial sites in Nagpur city, India. Heavy metal contents of Cd, Pb and As of soil were determined and revealed high levels of Cd and Pb industrial soil samples. Six bacteria were isolated from soil and characterized on the basis of morphological, physiological and biochemical characteristics: and 16S rRNA gene sequences viz; Alcaligenes sp. HM-7, Alcaligenes sp. HM-24, Alcaligenes sp. HM-27, Alcaligenes sp. HM-51, Bacillus cereus HM-85, Bacillus cereus HM-6. Biosorption and bioaccumulation capability of cadmium, lead and arsenic metals in six selected bacteria were studied. Cd, Pb and As tolerance was found highest in Alcaligenes faecalis HM-7 i.e 62.52%; Alcaligenes sp. HM-24, 82.56%; and Bacillus cereus HM-85, 29.42% respectively in bacterial isolates grown in nutrient media and supplemented with heavy metal. Similarly from nutrient deficient media supplemented with heavy metal showed 60% tolerance in Alcaligenes faecalis HM-7; 76.72% in Alcaligenes sp.HM-24 and 28.28% in Bacillus cereus HM-85 respectively with intracellular accumulation. The present study revealed that soil bacteria accumulated heavy metal in nutrient rich as well as nutrient deficient environment and could be potentially used in bioremediation of heavy-metal contaminated environment.
Keywords: Alcaligenes feacalis, Bacillus cereus, soil, heavy metals, resistance, bioremediation
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