초록
Propionic acid production by Propionibacterium freudenreichii from molasses and waste propionibacterium cells was studied in plant fibrous-bed bioreactor (PFB). With non-treated molasses as carbon source, 12.69+/-0.40gl<SUP>-1</SUP> of propionic acid was attained at 120h in free-cell fermentation, whereas the PFB fermentation yielded 41.22+/-2.06gl<SUP>-1</SUP> at 120h and faster cells growth was observed. In order to optimize the fermentation outcomes, fed-batch fermentation was performed with hydrolyzed molasses in PFB, giving 91.89+/-4.59gl<SUP>-1</SUP> of propionic acid at 254h. Further studies were carried out using hydrolyzed waste propionibacterium cells as substitute nitrogen source, resulting in a propionic acid concentration of 79.81+/-3.99gl<SUP>-1</SUP> at 302h. The present study suggests that the low-cost molasses and waste propionibacterium cells can be utilized for the green and economical production of propionic acid by P. freudenreichii.