College of Food Science and Technology, Nanjing Agricultural University, Nanjing, Jiangsu 210095, PR China.
Department of Food Science and Technology, Jinling College, Nanjing Normal University, Nanjing, Jiangsu 210095, PR China.
Int J Biol Macromol. 2023 Jan 1;224:292-305. doi: 10.1016/j.ijbiomac.2022.10.124. Epub 2022 Oct 17.
The cell surface of lactic acid bacteria (LAB) plays an essential role in cell-cell and cell-host interactions. Exopolysaccharides (EPSs) are produced on the cell surface of LAB or in the surrounding medium and are considered to be in favor of the strain- specific probiotic surface characteristics. In this work, the structure features of EPS from Lacticaseibacillus paracasei S-NB were analyzed preliminarily, and the genes involved in EPS biosynthesis of S-NB strain were hypothesized and annotated, and their role in phenotypic characteristics were demonstrated by gene deletion analysis. Four mutant strains with deletion of crucial genes involved in EPS synthesis were analyzed for strain characteristics that are closely related to their ability to interact with the host intestinal epithelium cells, including strain surface characteristics and viability under the gastrointestinal stress conditions (both acid and bile stress). Furthermore, the adherence and immunomodulatory properties of wild-type S-NB and its mutant strains were compared using Caco-2 and RAW 264.7 cell lines, respectively. Taken together, the results indicated the importance of genes associated with EPS biosynthesis in L. paracasei S-NB as a determinant in strain surface characteristics and cell-host interaction, especially for S-NB_2176 (responsible for EPS polymerization) and S-NB_2175 (responsible for CpsD/CapB family tyrosine-protein kinase).
乳酸菌（LAB）的细胞表面在细胞间和细胞与宿主的相互作用中起着至关重要的作用。胞外多糖（EPS）是在 LAB 的细胞表面或周围介质中产生的，被认为有利于菌株特异性益生菌表面特性。在这项工作中，初步分析了副干酪乳杆菌 S-NB 的 EPS 的结构特征，并假设和注释了 S-NB 菌株参与 EPS 生物合成的基因，通过基因缺失分析证明了它们在表型特征中的作用。分析了四个缺失参与 EPS 合成的关键基因的突变株，以研究与宿主肠上皮细胞相互作用能力密切相关的菌株特性，包括菌株在胃肠道应激条件下（酸和胆汁应激）的表面特性和生存能力。此外，使用 Caco-2 和 RAW 264.7 细胞系分别比较了野生型 S-NB 及其突变株的黏附和免疫调节特性。总之，这些结果表明与 EPS 生物合成相关的基因在副干酪乳杆菌 S-NB 中作为菌株表面特性和细胞与宿主相互作用的决定因素的重要性，特别是对于 S-NB_2176（负责 EPS 聚合）和 S-NB_2175（负责 CpsD/CapB 家族酪氨酸蛋白激酶）。
