Production of a non-cytotoxic bioflocculant by a bacterium utilizing petroleum hydrocarbon source and its application in heavy metal removal

A bacterium isolated from the activated sludge of an oil refinery of Assam, India retained efficient bioflocculating activity through production of bioflocculant when it was grown on crude oil amended media avoided of any other carbon source.The bioflocculating activity gained from the optimized media broth was 86.2%, which could be enhanced up to 89.1% with the purified bioflocculant. In course of bioflocculant production, the bacterium utilized about 77% of the petroleum hydrocarbons after incubation for 168 h when the activity was found to be the highest. The bioflocculant was efficient in flocculating Ni2+, Zn2+, Cd2+, Cu2+ and Pb2+. The bioflocculant was characterized as a glycoprotein complex by biochemical tests, FT-IR, SEM-EDX and LC/MS analyses. The bioflocculant showed negligible cytotoxicity on testing with L292 cell line indicating tremendous possibility of its use in bioremediation.