Biosorption of mercury and lead by aqueous Streptomyces VITSVK9 sp. isolated from marine sediments from the bay of Bengal,India

Toxic heavy metals are increasingly accumulating in the environment worldwide and are considered to be life threatening contaminants. The biosorption of mercury and lead by marine actinomycetes isolated from marine sediment collected from the Bay of Bengal coast of Puducherry, India, was evaluated. The maximum tolerance concentration (MTC) of Streptomyces sp. was determined by a well diffusion method and a broth dilution method. The effects of the initial metal ion concentration, the pH and the biomass dosage on the biosorption of mercury and lead ions were investigated. The MTC of the isolate to metals was 200 mg·L^-1 for mercury and 1800 mg·L^-1 for lead. At neutral pH, the isolate had a maximum biosorption of metal ions of 200 mg·L^-1 and 150 mg·L^-1 for mercury and lead respectively. Fourier transform infrared (FTIR) absorption spectra showed the chemical interactions between the functional groups in the biomass such as hydroxyl (-OH), amine (-NH₂), carboxyl (-COOH) and the metal ions. The isolate was further characterized by molecular taxonomy and identified as a member of the genus Streptomyces. Based on the phenotypic and phylogenetic analysis, the strain was classified as a new species of the genus Streptomyces and designated as Streptomyces VITSVK9 sp. (HM137310). A blast search of the 16S rDNA sequence of the strain showed the most similarity (95%) with Streptomyces sp. A515 Ydz-FQ (EU384279). Based on the results, it can be concluded that this marine Streptomyces could be used as a biosorbent for the removal of heavy metal ions from aqueous environments.