玻璃化转变温度和崩解温度对植物乳植杆菌冷冻干燥存活率的影响

Efects of Glass Transition Temperature and Disintegration Temperature on Freeze-Drying Survival Rate of Lactobacillus plantarum

摘要:

【目的】测定保护剂的玻璃化转变温度（T_g）和崩解温度（T_c）对植物乳植杆菌（Lactobacillus plantarum, L. plantarum）冷冻干燥存活率的影响。【方法】利用差示扫描量热（DSC）法和冷冻干燥显微镜（FDM）技术测定质量分数10%的蔗糖、质量分数10%的山梨醇以及PBS缓冲液等保护剂的T_g和T_c，并分析菌株在不同保护剂下的冷冻干燥存活率与T_g、T_c之间的关联性。【结果】保护剂菌悬液的T_g和T_c与菌株冷冻干燥存活率之间存在密切相关性。蔗糖组与山梨醇组和PBS组相比，T_g分别提高了7.2 ℃和7.7 ℃， T_c分别提高了8.0 ℃和8.8 ℃，且蔗糖组菌株的冷冻干燥存活率也最高，分别比山梨醇组和PBS组提高了49.2%和54.6%。进一步开发出高T_g的多糖复合保护剂，最佳复合保护剂的T_g和T_c相对于单一蔗糖保护剂分别提高了4.6 ℃和4.4 ℃，冷冻干燥存活率相对于单一蔗糖保护剂提高了28.2%。【结论】不同保护剂的T_g和T_c差异极大，并且T_g和T_c越高，菌株的冷冻干燥存活率越高。作者基于T_g开发了高效复合保护剂，有利于提高植物乳植杆菌冷冻干燥存活率。

Abstract:

[Objective] To determine the effects of glass transition temperature(T_g) and collapse temperature(T_c) of protectants on the freeze-drying survival rate of Lactobacillus plantarum(L. plantarum). [Method] The T_g and T_c of protectants, such as 10% sucrose, 10% sorbitol, and PBS buffer, were measured by differential scanning calorimetry (DSC) and freeze-drying microscopy (FDM). [Result] The relationship of the freeze-drying survival rate of strains with the T_g and T_c of different protectants showed that there was a close relationship of the freeze-drying survival rate of strains with the T_g and T_c of the protectant suspension. Compared to sorbitol and PBS groups, the T_g of sucrose group increased by 7.2 and 7.7 ℃, respectively, while T_c increased by 8.0 and 8.8 ℃, respectively. The freeze-drying survival rate of the sucrose group was the highest, showing improvements of 49.2% and 54.6% over the sorbitol and PBS groups, respectively. Furthermore, a high T_g polysaccharide composite protectant was developed. The T_g and T_c of the optimal composite protectant increased by 4.6 ℃ and 4.4 ℃ compared to those of a single sucrose protectant, and the freeze-drying survival rate was 28.2% higher than that of a single sucrose protectant. [Conclusion] The results showed that the T_g and T_c of different protectants were very different. As the T_g and T_c became higher, the freeze-drying survival rate was higher. Based on T_g, a highly efficient composite protectant was developed, which was beneficial in improving the freeze-drying survival rate of Lactobacillus plantarum.