Biosorption of Cr(III) and Cr(VI) by Streptomyces VITSVK9 spp.

The aim of the study was to evaluate the biosorption of heavy metals by actinomycetes isolated from marine sediment samples collected at the Bay of Bengal coast of Puducherry, India. The effect of initial metal ion concentration, pH and biomass dosage on biosorption of chromium ions was investigated. The isolate showed initial metal ion concentration of 80 and 100 mg l−1 for Cr(III) and Cr(VI), respectively, pH of 4.0 for Cr(III) and 7.0 for Cr(VI) with biosorption capacity of 76 and 84.27% for Cr(III) and Cr(VI), respectively. The biosorbent dosage was optimized as 3 g l−1 for both forms of chromium. The isolate showed the highest MTC (Maximum Tolerance Concentration) value of 1400 mg l−1 for Cr(VI) and 2,200 mg l−1 for Cr(III). The potential strain was characterized by polyphasic taxonomic approach 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). The BLAST search of 16S rDNA sequence of the strain showed highest similarity (95%) with Streptomyces sp. A515 Ydz-FQ (EU384279). The media and growth conditions were optimized for maximal growth under shake flask conditions by measuring the dry weight of mycelium. Maximal growth was seen with glucose as carbon source, peptone as nitrogen source and ammonium chloride as inorganic nitrogen. The growth of the isolate was maximal after 9 days of incubation at 35°C and pH of 7.0. Fourier transform infrared absorption spectrum results indicated that the chemical interactions between the functional groups hydroxyl (–OH), amine (–NH2), carboxyl (–COOH) and hydroxyl (–CHOH) of biomass and the metal ions. The results of our study revealed the biosorption property of metabolites produced by Streptomyces VITSVK9 spp. and this could be used as potential biosorbent for removal of heavy metal ions from aqueous environment.