Green synthesis of polyhydroxyalkanoate polymer by Bacillus iocasae

Abstract

Polyhydroxyalkanoates (PHAs) are bio-polyesters synthesized by various microbial species as a potential replacement for conventional fossil-fuel-based plastic. The aim of the present work was to produce PHAs by a bacterial isolate recovered from activated sewage sludge. The bacterial isolate was identified using 16S rRNA as Bacillus iocasae MMAS4. A Plackett-Burman (PB) design was used to estimate the PHA percentage content using the bacterial strain per 100 mL modified Luria-Bertani broth medium. Factors evidencing P values of less than 0.05 were considered to have significant effects on the PHA percentage. The production of PHAs was improved by adding stress factors such as ethanol, H 2 O 2 and a 1:1 mixture of both into the culture medium. B. iocasae is considered a novel PHA producer yielding 1.5 g L −1 PHAs. The produced PHAs were extracted and characterized. The functional groups of the extracted PHA granules were characterized as P(3HB-co-3-HV) copolyester (poly-3-hydroxybutyrate-poly-3-hydroxyvalerate) by Fourier transform infrared spectroscopy and 1 H NMR analyses. The results indicated the possible use of B. iocasae for the production of PHAs on media containing molasses, an inexpensive substrate as an alternative to the conventionally chemically synthesized polymers.