Functional Biomolecules Research Team, National Institute of Livestock and Grassland Science, Tsukuba, Ibaraki, 305-0901, Japan.
Folia Microbiol (Praha). 2009 Sep;54(5):395-400. doi: 10.1007/s12223-009-0055-0. Epub 2009 Nov 24.
The factors of bile tolerance (as one among the fundamental characteristics of probiotic bacteria) were determined in lactococci by using plasmid variants. Bile tolerance of Lactococcus lactis wild-type (WT) strains 527 and N7 (determined by viability counts on bile-containing agar) was equivalent to the corresponding plasmid-free derivatives. In contrast, L. lactis WT strain DRC1 had lower bile tolerance than its plasmid-free derivative DRC1021. Plasmid pDR1-1B, extracted from strain DRC1, was introduced into strain DRC1021 by co-transformation with the vector plasmid pGKV21 as an indicator. Strain DRC121 (DRC1021 harboring pGKV21) had good bile tolerance as did strain DRC1021, while strain DRC13 (DRC1021 harboring both pDR1-1B and pGKV21) did not. Fatty acid (FA) composition was different between strains DRC121 and DRC13. The plasmid pDR1-1B or plasmid profile and FA composition are key factors for bile tolerance of strain DRC1, and therefore changing the plasmid profile might be a way of modulating bile tolerance in lactococci.
通过使用质粒变体，确定了耐胆汁（作为益生菌细菌的基本特征之一）的因素在乳球菌中的存在。乳球菌野生型（WT）菌株 527 和 N7 的胆汁耐受性（通过在含胆汁的琼脂上的活菌计数来确定）与相应的无质粒衍生物相当。相比之下，乳球菌 WT 菌株 DRC1 的胆汁耐受性低于其无质粒衍生物 DRC1021。从菌株 DRC1 中提取的质粒 pDR1-1B 通过与载体质粒 pGKV21 共转化引入到菌株 DRC1021 中作为指示。菌株 DRC121（携带 pGKV21 的 DRC1021）和菌株 DRC1021 一样具有良好的胆汁耐受性，而菌株 DRC13（同时携带 pDR1-1B 和 pGKV21 的 DRC1021）则没有。菌株 DRC121 和 DRC13 之间的脂肪酸（FA）组成不同。质粒 pDR1-1B 或质粒图谱和 FA 组成是 DRC1 胆汁耐受性的关键因素，因此改变质粒图谱可能是调节乳球菌胆汁耐受性的一种方法。
