Economically enhanced succinic acid fermentation from cassava bagasse hydrolysate using Corynebacterium glutamicum immobilized in porous polyurethane filler

An immobilized fermentation system, using cassava bagasse hydrolysate (CBH) and mixed alkalis, was developed to achieve economical succinic acid production by Corynebacterium glutamicum. The C. glutamicum strains were immobilized in porous polyurethane filler (PPF). CBH was used efficiently as a carbon source instead of more expensive glucose. Moreover, as a novel method for regulating pH, the easily decomposing NaHCO₃ was replaced by mixed alkalis (NaOH and Mg(OH)₂) for succinic acid production by C. glutamicum. Using CBH and mixed alkalis in the immobilized batch fermentation system, succinic acid productivity of 0.42gL^-1h^-1 was obtained from 35gL^-1 glucose of CBH, which is similar to that obtained with conventional free-cell fermentation with glucose and NaHCO₃. In repeated batch fermentation, an average of 22.5gL^-1 succinic acid could be obtained from each batch, which demonstrated the enhanced stability of the immobilized C. glutamicum cells.