Heavy Metal Tolerance Exhibited by Bacterial Strains Sourced from Adyar River

Abstract

A total of five water samples were collected from Adyar River during the months of November 2010–2011 and were analyzed for different physico-chemical parameters like, temperature, pH, DO, Pb, Hg, Ni, Cd, and Cr levels. The results of the study indicate that the temperature was in the range 29–31 °C and pH 7.56–8.18 along the entire sampling time. The temperature and pH range was well within the limits as specified by the Tamil Nadu Pollution Control Board (TNPCB) for Inland surface waters and coastal areas. The Dissolved Oxygen levels were found to be very low, which did not exceed 2 mg/L, indicating a very poor water quality. The concentration of Pb was found (greater than 10 mg/L) to have crossed the limit of tolerance as prescribed by TNPCB (Pb-0.1 mg/L). Around 30 bacterial isolates from the Adyar waters were adapted for metal tolerance test by amending with heavy metals at different concentration (5–50 mg/L). The results of bioremediation/biosorption process indicated that, out of 30 strains, 15 strains reduced/absorbed lead effectively. Pre and post-treated waters were analyzed by AAS and confirmed by ICP-OES. Biochemical characterization of the potent strain, “L” indicated that it may be Actinomycetes.