PRODUCTION OF POLY-BETA-HYDROXYBUTYRIC ACID FROM CARBON-DIOXIDE BY ALCALIGENES-EUTROPHUS ATCC 17697T

The characteristics of PHB production from carbon dioxide by autotrophic culture of Alcaligenes eutrophus ATCC 17697T using a recycled gas closed circuit culture system under the condition of oxygen limitation were investigated. Cell concentration increased to more than 60 g/l after 60 h of cultivation, while the PHB concentration reached 36 g/l. PHB accumulation in the oxygen-limited culture was superior than that in an ammonium-deficient culture. The PHB produced was identified as a homopolymer of D-3-hydroxybutyrate by H-1 and C-13 NMR analysis. The stoichiometry for PHB production from CO2 under the oxygen limitation condition was indicated to be as follows: 33H2 + 12O2 + 4CO2 --> C4H6O2 + 30H2O. This stoichiometry shows that the hydrogen consumption per one mole of CO2 for PHB production is larger than that for cell formation.