Isolation and Characterization of Two PHA Producing Strains Isolated from Soil Sample of Nalgonda District

Abstract

Two whitish-colored gram-positive strains producing Polyhydroxyalkanoates (PHAs) were isolated from a soil sample from Nalgonda district in the Telangana state of India. With the help of Sudan black B staining, ten isolates with lipids, which showed bluish black color were selected from twenty-six bacterial strains which were selected randomly and purified from the serial diluted plate. Among ten isolates, 3D1 and 3D10 isolates were confirmed with Nile blue A and Nile Red staining for their PHA granules producing capacity. These two isolates grew optimally at a temperature of 37°C and a pH of 9. Furthermore, these strains were able to resist NaCl up to 10%, whereas, optimum NaCl required for the growth of 3D1 was 2%, but optimum NaCl required for the growth of 3D10 was shown to be 4%. PHAs produced by the two strains, 3D1 and 3D10, were extracted and quantified, which produced 68% PHA with a polymer concentration of 4.902 g/L and 61% PHA with a polymer concentration of 4.023 g/L, respectively. Biochemical, Morphological and Molecular characterization were performed on these two isolates. These two strains, 3D1 and 3D10, were closely related to Bacillus sonorensis with similarity of 99.51% and Bacillus safensis subsp. safensis with similarity of 99.66%, respectively. The 16S rDNA gene sequences of these two isolates were submitted to the NCBI Gene bank and the accession numbers were also sought.