乳酸菌在牡蛎酶解液中的生长特性及发酵条件优化

Growth Characteristics of Lactic Acid Bacteria in Enzymatic Hydrolyzate of Oyster and Optimization of Fermentation Conditions

以牡蛎酶解液为原料,通过测定培养液中OD值及乳酸菌数,探讨保加利亚乳杆菌、嗜热链球菌及干酪乳杆菌的生长特性。以滴定酸度、p H值为指标,通过神经网络平台建立这3株乳酸菌混合发酵牡蛎酶解液的神经网络模型,拟合确定发酵的最适宜条件。试验结果表明:3种乳酸菌被驯化后延滞期缩短,稳定期延长;保加利亚乳杆菌和嗜热链球菌的最适生长温度均为40℃,而干酪乳杆菌在36℃时生长繁殖最快。通过神经网络模型优化的这3株乳酸菌发酵牡蛎酶解液的条件:保加利亚乳杆菌、嗜热链球菌和干酪乳杆菌混合比例4∶2∶1,接种量(体积分数)7%,发酵温度40℃,发酵时间7 h。按此条件接种乳酸菌混合发酵7 h,牡蛎酶解液的滴定酸度为51.8°T,p H 4.41。

The growth characteristics of Lacctobacillus bulgaricus（L.b）, Streptoccus thermophilus（S.t） and Lactobacillus casei（L.c） in the enzymatic hydrolysate of Oyster were studied by determination the OD value of the wavelength at 600 nm and the number of lactic acid bacteria. The neural network model was established used titratable acidity and value of p H as the index. The fermentation conditions of the three strains of lactic acid bacteria were optimized by neural network. The results indicated the time of lag phase of Lactobacillus bulgaricus, Streptococcus thermophilus and Lactobacillus casei in the enzymatic hydrolysate of Oyster was shorten and the stationary phase was extended after acclimation. The optimum growth temperature of L. b, S. t and L. c in the enzymatic hydrolysate of Oyster was 40, 40 and 36℃, respectively. The fermentation conditions optimized by neural network were 4 ∶ 2 ∶ 1 of L. b ∶ S. t ∶ L. c with inoculum of7% at 40 ℃. After lactic acid fermentation for 7 h at their optimum conditions, the titratable acidity and the value of p H of Oyster fermentation broth were 51.8 °T and 4.41.