CONTINUOUS PRODUCTION OF LACTIC-ACID FROM DEPROTEINIZED WHEY BY COIMMOBILIZED LACTOBACILLUS-CASEI AND LACTOCOCCUS-LACTIS CELLS IN A PACKED-BED

The continuous production of lactic acid from deproteinized whey by im mobilized single and mixed culture of L. casei and L. lactis in Ca-alg inate beads has been investigated. A coimmobilized culture system gave better results than immobilized single cultures regarding lactic acid concentration, productivity, yield, and lactose utilization. Maximum lactic acid productivity of 7 g/1h was obtained at D=0.4 h(-1) with a yield of 70% lactic acid and 50% lactose utilization. At a dilution ra te of 0.1 h(-1), a lactic acid productivity of 2.5 g/1h was obtained w ith a 55.5% lactic acid yield and 90% lactose utilization. The bioreac tor system was operated at a constant dilution rate of 0.1 h(-1) for 2 0 days without toss of original activity. In this case, the average ta ctic acid productivity, lactic acid yield and lactose utilization were 24 g/1h, 55% and 90%, respectively.