不同保护剂影响植物乳杆菌冻干菌粉发酵活力的研究

Effect on the Fermentation Activity of Freeze-dried Lactobacillus plantarum by Cryoprotectant

以植物乳杆菌(Lactobacillus plantarum CGMCC 6016,L. P. dy-1)为分析对象,研究不同冻干保护剂、贮藏温度和贮藏时间对冻干菌粉活菌数及发酵活力的影响。研究分别采用10 %和22.4 %的纯菊粉、菊粉复合保护剂、脱脂乳复合保护剂制备冻干菌粉。结果显示,在-20 ℃贮藏8个月,其活菌数均可保持在1010 CFU/g以上;4 ℃贮藏8个月,仅菊粉复合保护剂组活菌数维持在较高水平,为(0.94±0.17)×1010 CFU/g;不同保护剂制备的冻干菌粉在-20 ℃下贮藏6个月或4℃下贮藏4个月,可维持较高的产酸活力,其中,菊粉复合保护剂组的细胞活力下降最为缓慢。流式细胞术(flow cytometry,FCM)与pH值测定法对细胞活力分析结果的关联度较好,R2值为0.77,可快速评价保护剂作用下冻干植物乳杆菌细胞的增殖;FCM分析结果显示,与脱脂乳复合保护剂相比,菊粉保护剂组与直接活化组的细胞增殖活力最为接近。

The influences on the viable count of freeze-dried Lactobacillus plantarum CGMCC 6016 (L. P. dy-1)during storage by different cryoprotectant were studied. And the fermentation activity of freeze-dried L. P. dy-1 affected by cryoprotectant was analyzed with the flow cytometry method (FCM). The results were as follows:10 % of inulin, 22.4 % of inulin, inulin composite protective agent and skim milk composite protective agent were used as cryoprotectant to protect the freeze-dried L. P. dy-1. The viable count of L. P. dy-1 was still higher than 1010 CFU/g after 8 months stored in -20 ℃, while only the viable count of inulin composite protective agent group kept a level higher than (0.94±0.17)×1010 CFU/g after 8 months stored in 4 ℃. The freeze-dried LAB with cryoprotectant could keep high acid production activity storage in -20 ℃ for 6 months and 4 ℃ for 4 months respectively. Among the cryoprotectant groups, the cell activity of the inulin composite protective agent group has the slowest decline. The correlation degree R2 between the results of pH value and FCM was 0.77, which indicated that FCM was suitable for the study of cell activity of freeze-dried L. P. dy-1. Compared with the freeze-dried L. P. dy-1 added with skim milk composite protective agent, the bacteria prepared with inulin cryoprotectant could keep a higher fermentation activity and similar cell proliferation activity with the direct activation group.