Streptomyces incanus BK 128 isolated from the Rhizosphere of eggplant was employed for polyhydroxybutyrate (PHB) production from different agriculture waste wheat bran, rice bran, rice straw and from molasses as the main carbon sources. Some supplements such as (0.4 g) ammonium sulphate to optimize the PHB production medium. The maximum PHB production was achieved with wheat bran (1.9g/l). Different parameters including; initial pH of the medium, ammonium chloride concentration and inoculum size; were carried out under shaking flask conditions (150 rpm) at 30ºC for 5 days of incubation to enhance the PHB production. The maximum PHB production (2.82gl-1) was achieved at pH 6.5, (2%) NH4CL and 5 ml inoculum size, respectively. The effect of gamma irradiation on the activity of Streptomyces incanus BK 128 towards PHB production showed that, at dose level 1.5 kGy the maximum PHB production obtained was 3.39 gl-1.
Keywords: Biopolymer /PHB/ Streptomyces incanus / Wheat bran/ rice bran.