Optimization and scale-up of propionic acid production by propionic acid-tolerant Propionibacterium acidipropionici with glycerol as the carbon source.

Propionic acid production by Propionibacterium acidipropionici with glycerol as sole carbon source was studied in 7-L batch and 10m(3) bioreactor cultures. In batch cultures, propionic acid production increased and specific cell growth rate decreased with increasing glycerol concentrations. Maximum propionic acid production and productivity reached 44.62+/-1.12g/L and 0.20+/-0.0075gL(-1)h(-1)at 220h, respectively, when glycerol was fed at a constant rate of 0.01L/h from 72 to 120h with an initial glycerol concentration of 30g/L. In the 10m(3) bioreactor, maximum propionic acid production reached 47.28+/-0.12g/L at 240h. This glycerol feeding approach may be useful for propionic acid production on an industrial scale.