Nutrient optimization of polyhydroxyalkanoate production from palm oil fiber by Ralstonia eutropha TISTR 1095 using response surface methodology

Polyhydroxyalkanoate (PHA) is polyesters formed in several bacteria as a carbon or energy storage under some nutrientlimitation. Ralstonia eutropha has potential to produce PHA from various substrates, including carboxylic acids. In this research,the nutrient optimum to produce PHA from carboxylic acid was studied by using response surface methodology. Thecarboxylic acids were produced by anaerobic palm oil fiber fermentation for 7 days. Then Ralstonia eutropha TISTR 1095was cultured in fermented broth containing 840 mg/l of acids. The interaction of two factors at the same time was investigated.The effects of propionic acid, butyric acid, (NH4)2SO4 and K2HPO4 addition were examined. The result showed that the nutrient optimum for PHA production was fermented broth with nutrient addition (2.50 g/l propionic acid, 6.53 g/l butyric acid,1.53 g/l, (NH4)2SO4 and 0.03 g/l K2HPO4). The cell concentration, PHA concentration, and PHA content were 1.53 g/l, 0.70 g/l and 46.5%, respectivel