摘要
The improvement of propionic acid production for antifungal activity, as fermenting by calcium alginate immobilized cells of Propionibacterium acidipropionici TISTR 442 was investigated by using whey as substrate. Optimal condition for immobilization was performed by adjusting tube distance to CaCI2 solution to be 4-6 cm and 7 mL/min flow rate of alginate gel. The production of propionic acid by immobilized cells in a 2 L fermentor using 1% CaCO3 and 5 N KOH to control the pH at 6.5 gave maximum propionic acid and they had consistent potential to recycle 2 rounds of fermentation and produced the total of 29.24 g/L propionic acid （15.85 ± 0.25 g/L and 13.39 ± 0.25 g/L propionic acid from Batch 1 and Batch 2 fermentation, respectively）. Compared to free-cell fermentation, propionic acid productivity increased 20% （0.083 g/h vs. 0.070 g/h） and fermentation time reduced 11% （192 h vs. 216 h） in 2 L fermentor with 40 g/L initial total sugar from whey. The fermented propionic acid as well as the commercial propionic acid from chemical process was able to inhibit the growth of the fungal tested.
