Analysis of the effect of acid stress in Lactococcus lactis MG1363

To understand the system response to pH changes in the environment, the expression of genes during the pH shift was investigated. Pre-adaptation effects were examined by comparing the effects seen with cells pre-grown in pH 5.1 or pH 6.5 to those occuring after a sudden pH change (pre-grown in pH 6.5, and suspended in buffer of pH 5.1). mRNA of L. lactis MG1363 cells grown at pH 6.5 and suspended in 50 mM KPi buffer, pH 5.1 and of those grown at pH 5.1 and suspended in 50 mM KPi buffer, pH 5.1 were compared. Control experiment was performed with mRNA of cells grown at pH 6.5 and suspended in buffer of pH 6.5 compared to that of cells grown in pH 5.1 and suspended in buffer of 5.1.

为探究该系统对环境pH变化的响应，本研究对pH转移过程中的基因表达情况展开了研究。通过对比分别在pH 5.1或pH 6.5中预培养的细胞所产生的效应，与经历突发pH变化（即在pH 6.5中预培养后，重悬于pH 5.1缓冲液中）后的效应，考察了预适应效应。本研究比较了两类样本的信使核糖核酸（messenger RNA，mRNA）：一类为在pH 6.5中培养、重悬于50 mM KPi缓冲液（pH 5.1）的乳酸乳球菌MG1363（L. lactis MG1363）细胞，另一类为在pH 5.1中培养、重悬于50 mM KPi缓冲液（pH 5.1）的同菌株细胞。对照组实验设置为：比较在pH 6.5中培养并重悬于pH 6.5缓冲液的细胞的mRNA，与在pH 5.1中培养并重悬于pH 5.1缓冲液的细胞的mRNA。