初始乳糖浓度对酸奶菌株分批发酵的影响

探究了初始乳糖浓度对酸奶菌株发酵过程的影响。在2.5L发酵罐中分别培养德氏乳杆菌保加利亚亚种KLDS 1.9201和唾液链球菌嗜热亚种KLDS 3.021，培养基中初始乳糖浓度范围为30～90g/L，并详细分析了发酵全过程的动力学参数包括乳糖消耗，细菌数增长和乳酸生成。结果表明，较高乳糖浓度并不利于菌体生长，确定较为适宜的初始乳糖浓度分别为50 g/L和70 g/L，前者条件下KLDS 3.0201的乳糖转化率达到85.3%，最高乳酸浓度达到36 g/L，增殖6h后的活菌数为4.4×109 CFU/ml，后者条件下KLDS 1.9201的乳糖转化率达到85.7%，产生的最高乳酸浓度达到52g/L，发酵培养8h后的活菌数约为2.15×109CFU/ml。

Effects of Initial Lactose Concentration on Batch Fermentation of Two Yoghurt Strains

In the present study, two yoghurt strains, Lactobacillus bulgaricus (KLDS 1.9201) and Streptococcus thermophilus (KLDS 3.0201) were cultured in 2.5-L fermentor with four initial lactose concentrations ranging from 30 to 90 g/L, and the process kinetic parameters including lactose consumption, cell number inrease and lactic acid production were investigated. The results indicated that the higher concentration of lactose had an inhibitory effect, and the initial lactose at a concentration of 50 g/L or 70 g/L was suitable. Under the former concentration, the lactose utilization rate by KLDS3.0201 reached 85.3%, the lactic acid production reached 36 g/L, and the living bacterial population was up to 4.4×109 CFU/ml after 6 h growth. Under the latter concentration, the lactose utilization rate by KLDS1.9201 reached 85.7%, the lactic acid production reached 52 g/L, and the living bacterial population was up to 2.15×109 CFU/ml after 8 h growth.