Optimization of production of poly-hydroxy butyrate biopolymer using Streptomyces native bacteria

Abstract Synthetic polymers are mostly made of petroleum, remain in the soil for a long time because they are not biocompatible. Production of biodegradable polymers, like poly-beta-hydroxy butyrate (PHB), is a new way to increase degradation rate of polymers in the environment. In this study, five strains of Streptomyces native bacteria were isolated and coded as G2 (Streptomyces ambofaciens Azar411), 6, G8, E17, and N5 and were used for production of PHB. Granules of PHB were observed within all five strains after treatment by prepared nutrient agar culture medium. Nutrient Broth medium was centrifuged at the end of PHB production stage. The amount of produced PHB was analyzed by Gas Chromatography-Mass Spectrometry and calculated by spectrophotometry and weighing method. The effects of six important parameters including carbon and nitrogen sources, pH and temperature of culture medium, shaker speed, and incubation time, on the amount of PHB production were assessed and their optimum values were obtained. Maximum PHB production was obtained in G2 bacteria as 77.51%, of cell dry weight, after 2days at culture medium with same values of parameters as extraction phase except that 1g peptone protease as nitrogen source, and 4 mL aqueous glucose solution as carbon source were used.