Piyarat Boonsawang and Thongchai Wongsuvan

pp. 9 - 16

Abstract

Polyhydroxyalkanoate (PHA) is polyesters formed in several bacteria as a carbon or energy storage under some nutrient
limitation. 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. The
carboxylic acids were produced by anaerobic palm oil fiber fermentation for 7 days. Then Ralstonia eutropha TISTR 1095
was 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)₂
SO₄ 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)₂
SO₄ 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%, respectively.