ROLE OF BACTERIA IN BIO SORPTION OF HEAVY METALS.

Presented study was focussed on isolation and screening the heavy metal resistant microbes and to evaluate the biosorption potential of heavy metals from contaminated soil of Bhagwanpur industrial area. Soil samples for the study were randomly collected from Bhagwanpur industrial area. The soil sample was analysed for different physico-chemical properties such as pH, moisture content, temperature, water holding capacity, carbon, organic matter, total nitrogen and available phosphorous. Heavy metal resistant bacteria were isolated and screened for their biosorption potential. The minimum inhibitory concentration (MIC) of Pb, Cr, Ni and Zn was determined by agar diffusion method. The selected bacterial isolates were identified by gram staining and biochemical parameters. Isolates were further characterized molecularly with 16S rRNA gene sequence analysis. Furthermore, biosorption capacity i.e. amount of metal ion (mg) bioabsorbed/g of dried biomass was calculated for identified strains. Carbon and organic matter content was found to be 0.23 ± 0.1% and 0.33 ± 0.08% respectively, while nitrogen in the sample was 0.34 ± 0.07 %. Among ten isolates only four bacteria showed resistance against metals (Ni, Cr, Pb and Zn). MIC range of isolates against various metal concentrations was in the range of 25 PPM to 400 PPM. Molecular characterization of the isolates revealed 99% similarities of S44, S3B, S12 and S13 with Staphylococcus gallinarum, Acinetobacter pitti and Pantoea agglomerans and Enterobactor spp. respectively. Biosorption experiments indicated that, Acinetobactor spp. (S3B) and Enterobactor spp. (S13) could bioadsorb metals in the order Zn>Pb>Ni>Cr; Staphylococcus spp. (S44) showed in Ni>Zn>Cr>Pb; Pantoea spp. (S12) in order Zn>Ni>Pb>Cr. Thus, Biosorption was influenced by the initial metal concentration. Among the isolated bacterial strains, biosorption capacity was found in order as Acinetobacter calcoaceticus> Enterobacter spp.> Staphylococcus gallinarum> Pantoea agglomerans. In this study Cr, Zn, Pb and Ni resistant bacteria were isolated from heavy metal contaminated soil. Tolerance data with extremely high range of heavy metal concentrations, revelaed that heavy metal resistant bacterial isolates can tolerate metal toxicity up to 400. Thus paving a new way for safe, reliable and cost-effective treatment of heavy metal contaminated soil around the world.