1a. Objectives (from AD-416):
1) To determine succinic acid yield using glucose and xylose media at several levels of H2 gas supplied to the fermentor by sparging into the media. 2) To demonstrate the gas mixture produced by T. neapolitana fermentation (CO2 and H2) can be used to increase succinic acid yield.
1b. Approach (from AD-416):
Succinic acid. SA fermentations using strain E. coli AFP184 grown on both glucose and xylose media will be conducted. The H2-rich gas stream from the hydrogen bioreactor will be introduced to head space of the succinic acid fermentor and/or bubbled through the liquid to determine impact on SA yield, as compared to control.
3. Progress Report:
Succinic acid production using peach cull media and E. coli AFP184 was successfully demonstrated in bench-scale fermentors. The fermentation process included an aerobic growth phase and a subsequent anaerobic production phase. Complete consumption of all available fermentable sugars in the media and higher production rates and yields were achieved by corn steep liquor supplement and hydrogen sparging into the fermentor during the anaerobic production phase. Sparging of hydrogen also raised the molar ratio of succinate:acetate from 5:1 to 8:1, which would reduce succinic acid recovery and purification cost in an industrial process.