Isolation and characterization of heavy metal resistant bacteria and its effect on shoot growth of Oryza sativa inoculated in industrial soil

Abstract

A total of twenty heavy metal resistant bacteria were isolated from industrial effluents, sewages, garages and petrol pumps of Barak valley region of Assam, India, against copper, zinc, and lead. Decrease in total count and microbial population diversity with increasing metal concentrations were observed.The predominant isolates obtained were Pseudomonas sp., Klebsellia sp. and Bacillus sp. with minimum inhibitory concentration for heavy metals as 60μg/ml (for copper), 180μg/ml (for lead) and 1800μg/ml (for zinc). The present study demonstrated that the isolates having higher tolerance to heavy metals have high resistance pattern towards a group of antibiotics. Pot experimental studies suggest that the isolated bacterial communities live in association with rhizosphere soil and able to withstand high heavy metal concentrations in contaminated soil. Further, it has been observed that a significant increase in shoot length of Oryza sativa in contaminated soil when inoculated with heavy metal resistant bacterial strains.