Biosynthesis and characterization of polyhydroxyalkanoate from marine Bacillus cereus MCCB 281 utilizing glycerol as...

Polyhydroxyalkanoates (PHAs) are aliphatic polyesters produced by bacteria from renewable resources which serve as a substitute of synthetic plastics. In the present study isolation, screening, identification of PHA producing bacteria from marine water samples and optimization of process variables for increased PHA production were accomplished. The potent isolate identified as Bacillus cereus MCCB 281 synthesized PHA co-polymer with 13 mol% 3-hydroxyvalerate in presence of glycerol. Process parameters optimized using central composite design for enhanced PHA production showed 1.5 fold higher PHA yield. Cell dry weight of 3.72 ± 0.04 g L^-1, PHA yield 2.54 ± 0.07 g L^-1 and PHA content of 68.27 ± 1.2% (w/w) was achieved in fermenter at the optimized conditions. Purified polymer was characterized by Fourier-transform infrared spectroscopy, Nuclear magnetic resonance spectroscopy, Gas chromatography-Mass spectrometry, X-ray powder diffraction techniques and molecular weight of PHA was found to be 2.56 × 10⁵ Da. PHA nanoparticles with average particle size 179 nm were synthesized for medical applications and biocompatibility analysis was performed with L929 mouse fibroblast cell line. This is the first report of a moderately halophilic B. cereus, which utilizes glycerol as the sole carbon source for PHA co-polymer production.