Van Heerden, Carel DanielNicol, Willie2013-07-022013-07-022013-04-15Van Heerden, CD & Nicol, W 2013, 'Continuous succinic acid fermentation by Actinobacillus succinogenes', Biochemical Engineering Journal, vol. 73, no. 4, pp. 5-11.1369-703X (print)1873-295X (online)10.1016/j.bej.2013.01.015http://hdl.handle.net/2263/21781Fermentations were performed in an external recycle bioreactor using CO2 and D-glucose at feed concentrations of 20 and 40 g L . Severe biofilm formation prevented kinetic analysis of suspended cell (‘chemostat’) fermentation, while perlite packing enhanced the volumetric productivity by increasing the amount of immobilised cells. The highest productivity of 6.35 g L h was achieved at a dilution rate of 0.56 h . A constant succinic acid yield of 0.69±0.02 g/(g of glucose consumed) was obtained and found to be independent of the dilution rate, transient state and extent of biofilm buildup — approximately 53% of the carbon that formed phosphoenolpyruvate ended up as succinate. Byproduct analysis indicated that pyruvate oxidation proceeded solely via the formate-lyase pathway. Cell growth and corresponding biofilm formation were rapid at dilution rates higher than 0.35 h when the product concentrations were low (succinic acid<10 g L ), while minimal growth was observed at succinic acid concentrations above this threshold.en© 2013 Elsevier Ltd. All rights reserved. Notice : this is the author’s version of a work that was accepted for publication in Biochemical Engineering Journal. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Biochemical Engineering Journal, vol.73, no. 4, 2013, DOI : 10.1016/j.bej.2013.01.015Continuous fermentationSuccinic acidActinobacillus succinogenesBioreactorsBiofilmsGlucosePostprint Article