Cr (VI) resistant Bacillus and Acinetobacter isolated from soil of Narran valley

Abstract

Narran valley is famous for its beauty however anthropogenic activities are not only destroying the beauty of this valley but also lead to the pollution. Cr (VI) is considered as a major environment pollutant as it is mutagenic, carcinogenic and teratogenic. Current study deals with an attempt to know the Cr (VI) reduction potential of the indigenous bacterial isolates of soil of Narran valley. Total ten bacterial strains (JM1, JM5, JM6, JM7, JM8, JM9, JM10, J11, JM12, and JM13) were isolated from Narran valley soil. The morphological and biochemical characterization of selected strains were done. Maximum tolerable concentration of K2Cr2O4 was found to be 300 mgL for all of these strains. These bacteria were found to have multiple metal resistance. These strains could efficiently convert hexavalent chromium into trivalent form (96-98%) at an initial concentration of 300 μg mL of Cr (VI). In comparison with other purified isolates, (JM8) exhibited highest Cr (VI) reduction potential at all the preliminary concentrations (100, 300 and 900 μg mL). Best carbon and nitrogen sources for Cr (VI) reduction were sodium acetate and yeast extract, respectively. 16S rRNA gene sequencing revealed that JM9 and JM13 showed 99% similarity with genus Bacillus whereas JM8 was found to be homologous to genus Acinetobacter. FTIR study showed the contribution of sulphonate, carboxyl, amino and S-H groups of bacterial cell surface in the metal binding process. These chromium resistant bacterial isolates can be appropriate candidate for the remediation of chromate contaminated areas.