Fermentation strategy for the production of poly(3-hydroxyhexanoate) by <Emphasis Type="Italic">Aeromonas sp.</Emphasis> KC014

Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (P(3HB-co-3HHx)) was produced by Aeromonas sp. KC014 strain isolated from Taiwan in soil environment in the flask and fermentor cultures. The medium optimization, such as carbon source and nitrogen source, carbon-nitrogen ratio was conducted to obtain the optimum 3-hydroxyhexanoate content. The defined medium with dodecanoic acid as the carbon source and (NH₄)₂SO₄ as the nitrogen source was obtained as the main medium. When cells grown in medium containing 30 g/L dodecanoic acid, 15 g/L sodium gluconate and 1 g/L soytone (C/N was 30/1) as final PHA concentration, the cell dry weight and HB content of 5.16 g/L, 14.0 g/L and 36.0%, respectively, were obtained. The maximum HHx/PHA content increased from 0.1% to 1.3% nearly 12-fold when the dissolved oxygen was decreased from 40% to 20%. P(3HB-co-3HHx) biosynthesis was triggered by the addition of limited nitrogen, phosphorus and magnesium to get a maximum HHx/PHA content of 14% in 95 hours. This work was presented at 13 ^th YABEC symposium held at Seoul, Korea, October 20–22, 2007.