Abstract:
The optimal cultivation conditions for poly-β-hydroxybutyrate production from Alcaligenes sp. A-04 are followings : pH controlled at 7.0, amount of dissolved oxygen adjusted to 100% saturation at 30 degree celsius with agitation speed at 600rpm ; aeration rate at 1.8 vvm. At the beginning, in shake flask cultivation with the amount of ammonium sulfated at 0.1 g/l and 10.0 g/l of fructose, at 48 hours of cultivation, 47%/dry cell weight of PHB is obtained. In batch cultivation in 5 L. fermentor, it was found that the maximum amount of PHB produced is 7.21 g/L or 82.12%/dry cell weight at 72 hours of cultivation when the amount of ammonium sulfate and fructose equal to 1.5 g/L and 30.0 g/L respectively. Cane molasses was utilized by Alcaligenes sp. A-04 for PHB production although the amount of PHB produced was less than using fructose as a carbon source. About 2.3 g/L or 53.66%/dry cell weight of PHB was formed at 72 hours of cultivation when 20% (weight/volumn) of molasses was used as a carbon source and 0.1 g/L of ammonium sulfate as a nitrogen source. In fed-batch culture, the maximum amount of PHB produced from Alcaligenes sp. A-04 at 48 hours of cultivation was 6.56 g/L or 79.23 %/dry cell weight when the initial amount sulfate and fructose equal to 1.0 g/L and 10.0 g/L respectively, at 48 hours of cultivation, ammonium sulfate and fructose were added to make up the final concentrations to 1.0 g/L and 20.0 g/L respectively.