Biosynthesis and statistical optimization of polyhydroxyalkanoate (PHA) produced by Bacillus cereus VIT-SSR1 and fabrication of biopolymer films for sustained drug release

Abstract

Polyhydroxyalkanoates are a fascinating group of biological polymers, which have attracted extensive attention. An effectual PHB accumulating Bacillus cereus strain VIT-SSR1 was isolated from industrial effluent contaminated site. Plackett-Burman design was used to screen the critical factors affecting PHA production. Response surface method was employed to evaluate the interactive effects between the independent variables. The Central composite design was performed to optimize the concentrations of Molasses, ammonium sulphate and initial pH. A PHA content of (1.42 ± 0.01) g/L and a maximum PHA yield of (40.3 ± 0.77) % was obtained on implementing the optimized conditions. The produced biopolymer was analysed using Fourier transform infrared spectroscopy (FT-IR) and Gas chromatography-mass spectrometry analysis(GC–MS) and the thermal properties of the biopolymer were evaluated by Thermogravimetric analysis (TGA), and from the Nuclear magnetic Resonance (NMR) analysis the biopolymer was identified to be polyhydroxybutyrate (PHB). PHB-chitosan blends were prepared and tested for biocompatibility by MTT assay on L929 mouse fibroblast cell lines. Curcumin, a well-known drug was loaded onto PHB-chitosan films and their drug release pattern was observed. Curcumin showed a sustained mode of drug release. PHB films are biocompatible and can act as a potent polymer matrix for drug release studies.