为提高罗伊氏乳杆菌的冻干存活率及产业化制备效率,系统解析不同种类保护剂对该菌的保护效果并优化高密度冻干工艺降低冻干体积。首先将不同分子量、不同种类的单糖(醇)、二糖(醇)、低聚糖、多糖和蛋白质分别与罗伊氏乳杆菌的菌泥混合冻干测定存活率,然后研究不同分子质量的保护剂复配,及优势保护剂复配其他类物质对菌体的冻干保护效果,最后优化冻干前菌体与保护剂的比例和菌悬液总干物质含量。结果表明,低聚糖对罗伊氏乳杆菌具有最好的冻干保护效果,分子质量大小不同的物质以不同比例复配均不会提高保护效果,谷胱甘肽、甜菜碱、氨基酸、核苷酸、无机盐、维生素等物质均未显著提高低聚糖对该菌的冻干保护效果。菌泥与低聚糖类保护剂以干重比为1∶1.2混合时,具有最高的冻干存活率,冻干前菌悬液总干物质质量分数最高为29%时菌体存活率达90%以上。该研究结果为乳杆菌的高效冻干提供了指导。
In order to improve the freeze-drying survival rate and prepare efficiently for industrial production of Lactobacillus reuteri, the effect of different kinds of protective agents on the bacteria was systematically analyzed. The high-density freeze-drying process was optimized to reduce the freeze-drying volume. Firstly, the bacterial mud of L. reuteri, mixed with different molecular weights and kinds of monosaccharides (alcohols), disaccharides (alcohols), oligosaccharides, polysaccharides and proteins were lyophilized and the survival rate were measured. Then, the protective effect of lyoprotectants with different molecular weights and preponderant lyoprotectants compounded with other substances on the bacteria were studied. Finally, the ratio of the bacteria to the protective agent and the dry matter content in bacterial suspension were optimized before lyophilization. The results showed that oligosaccharides had the best lyophilization effect on L. reuteri and substances with different molecular weights in different proportions did not improve the protection effect. The glutathione, betaine, amino acids, nucleotides, inorganic salts, vitamins and other substances did not significantly improve the freeze-drying protective effect of oligosaccharides on the bacteria. When the bacterial mud and oligosaccharide protective agent were mixed at a dry weight ratio of 1∶1.2, the freeze-drying survival rate was the highest. And the freeze-drying survival rate was more than 90% when the dry matter concentration of the bacterial suspension was 29%. The results provided guidance for the efficient lyophilization of Lactobacillus.
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