Zhang Chaolei, Wang Chao, Zhao Shan, Xiu Zhilong
School of Life Science and Biotechnology, Dalian University of Technology, Linggong Road 2, Dalian, 116024, China.
Laboratory of Environmental Technology, INET, Tsinghua University, Beijing, 100084, China.
Biotechnol Lett. 2021 Mar;43(3):677-690. doi: 10.1007/s10529-020-03055-0. Epub 2021 Jan 1.
Probiotics (Bacillus subtilis 04178) were entrapped in alginate-chitosan microcapsules by high-voltage electrostatic process. The encapsulation pattern was established as entrapped low density cells with culture (ELDCwc). The performance of ELDCwc cells was investigated against stress environments of simulated digestive fluids.
After incubation in simulated gastric (pH 2.5) and intestinal fluids (4% bile salt) for 2 h, the survival rate of ELDCwc cells (18.19% and 27.54%) was significantly higher than that of the free cells (0.0000009% and 0.0005%). The reason why B. subtilis embedded in microcapsules can resist the stress environments was that the mass production of extracellular proteins and polysaccharides prompted B. subtilis to form cell aggregates. The production of extracellular proteins and polysaccharides were regulated by the concentration of c-di-GMP and the expression of ydaJKLMN operon, abbA, sinI, slrA, slrB, abrR and sinR.
c-di-GMP is important for the production of extracellular polymer substance to enhance probiotic viability in stress environments.
通过高压静电法将益生菌（枯草芽孢杆菌04178）包埋于海藻酸钠-壳聚糖微胶囊中。确定包封模式为包埋低密度培养细胞（ELDCwc）。研究了ELDCwc细胞在模拟消化液应激环境中的性能。
在模拟胃液（pH 2.5）和肠液（4%胆盐）中孵育2小时后，ELDCwc细胞的存活率（分别为18.19%和27.54%）显著高于游离细胞（分别为0.0000009%和0.0005%）。包埋于微胶囊中的枯草芽孢杆菌能够抵抗应激环境的原因是细胞外蛋白质和多糖的大量产生促使枯草芽孢杆菌形成细胞聚集体。细胞外蛋白质和多糖的产生受环二鸟苷酸（c-di-GMP）浓度以及ydaJKLMN操纵子、abbA、sinI、slrA、slrB、abrR和sinR表达的调控。
c-di-GMP对于细胞外聚合物的产生很重要，有助于提高益生菌在应激环境中的活力。
