keywords: Polyhydroxyalkanoates, Rhodobacter sphaeroides ADZ101, Plastic, Two level factorial
The composition and type of polyhydroxyalkanoates (PHA) monomers are related to bacterial strain and media composition. This study evaluate the optimum media composition of PHA accumulation by photosynthetic bacterium, Rhodobacter sphaeroides ADZ101. Two level factorial design of response surface methodology was used to determine the optimum media composition for the production of PHA. The results showed that acetate and NH4 Cl were the best carbon and nitrogen sources good for the study. The optimum PHA accumulation were found to consist the combination of 3.00 g/L acetate, 0.06 g/L NH4 Cl and pH 7. The predicted combination was found to be in agreement with experimental results with R-squared value of 0.9962. The diagnostic plots for response were also in conformity with the results of the experimental runs in the study. Hence accumulation of PHA by Rhodobacter sphareoides ADZ101 occurs under stress conditions of excess carbon and limited nitrogen.