LAUSR

Abstract The utilization of the juice from the cheapest carbon source oil palm frond (22 $/ton) in a 3.5 L bioreactor was proven to be competent in replacing pure sugar in succinic acid production. The current study provides an in-depth discussion on the utilization of CO 2 in the production of succinic acid. In the serum-bottle fermentation, the yield of succinic acid increased by 51% from 0.47 to 0.71 g/g while the final titer of succinic acid enhanced by 4 fold were attributed to the anaplerotic reaction of Actinobacillus succinogenes and the alkalinity effect of the dissolved CO 2 . In the bioreactor, the highest mass transfer in the fermentation medium was achieved at 0.5 vvm CO 2 at which 3 M KOH was pumped in at a rate of 2.0 mL/min to neutralize the carbonic acid formation, which afforded the highest succinic acid concentration of 30.7 g/L. A first report on actual stoichiometry equation relating substrate, CO 2 consumption and all products formation was derived from the results of bioreactor fermentation to lay as a guideline for future reference of actual succinic acid production reaction. C 6 H 12 O 6  + 0.145 NH 3  + 0.642 CO 2  → 1.083 C 4 H 6 O 4  + 0.509 CH 2 O 2  + 0.420 C 2 H 4 O 2  + 0.117 C 2 H 5 OH + 0.726 CH 1.8 N 0.2 O 0.5  + 0.614 H 2 O. Actual stoichiometry equation revealed that for every kg of succinic acid produced, 0.22 kg of CO 2 will be absorbed. The desirable effect of CO 2 on the production of succinic acid may translate into a mutually-beneficial relationship between the succinic acid and the CO 2 -generating biofuel industries.