PHBV production by Ralstonia eutropha in a continuous stirred tank reactor

Ralstonia eutropha was cultivated in a continuous-stirred tank reactor to study the dynamic responses of PHBV production under pH-state. The effects of carbon sources (glucose and sodium propionate) and dilution rate on microbial growth and PHBV accumulation were studied. In feeding substrates containing less than 3 g/L of sodium propionate, PHB was the major product with only small amounts of HV accumulated. When the feeding substrates contained 5 g/L of sodium propionate, HV began to accumulate in the product, averaging a HB to HV molar ratio of 70:30. When the feed contained 7 g/L of sodium propionate, the average HB to HV molar ratio was approximately 60:40. Feeding substrate containing 15 g/L of sodium propionate had an average HB to HV molar ratio of 40:60. The continuous culture systems did not reach significant steady states when the concentration of sodium propionate exceeded 7 g/L. 2005 Elsevier Ltd. All rights reserved.