Perspectives of Polyhydroxyalkanoate (PHAs) Biopolymer Production Using Indigenous Bacteria: Screening and Characterization

There are wide range of biopolymers synthesized by diverse group of bacteria, among them intracellular polyhydroxyalkanoates (PHA) is on the priority list based on its higher level of uses and extensive studies on the processes involved in its biosynthesis. This study focused on screening of indigenous bacterial strains for PHA production. Twenty-six different indigenous bacterial strains have been inventoried and exploited for biopolymer production. The screened bacteria stained bluish-black to purple colonies upon staining with Sudan Black B indicating their potency for PHA production. The inclusion bodies produced strong orange fluorescence with staining by Nile Blue A which were further confirmed by microscopic examinations. The size distribution of PHA granules ranged from 0.5 to 1.0 ìm with the mean value of 0.5 ± 0.06 ìm. Out of 26 strains, Bacillus sp. Strain-6 and Pseudomonas sp. Strain-16 has been recognized as a potential candidate for biopolymer production and further identified through 16S rRNA gene analyses. The PHA yield of the two potent bacterial isolates being 0.84 and 1.12 g/L, and recorded 55.4 and 71.1% yield of PHA in cell dry weight (CDW), respectively. FT-IR Spectroscopic analysis of biopolymer produced by the two strains revealed two main absorptions peaks at C–H and carbonyl stretching bands characteristic to PHA. The H1 and C13 NMR spectra confirmed the presence of -CH- group in PHA extracted from the two strains