College of Food Science, Shenyang Agricultural University, Shenyang 110866, PR China.
Int J Food Microbiol. 2011 Jun 30;147(3):181-7. doi: 10.1016/j.ijfoodmicro.2011.04.003. Epub 2011 Apr 16.
Tolerance to acid is an important feature for probiotic bacteria during transition through the gastrointestinal tract. Proteomics analysis of a new probiotic bacterium, Lactobacillus casei Zhang, was performed upon 30-min exposure to low acid stress (pH 2.5 vs. pH 6.4) using two-dimensional electrophoresis. Out of 33 protein spots that showed changes of expression between the two pHs, 22 showed 1.5-fold higher expression at pH 2.5 than at pH 6.4, whereas five spots had expression decreased by 1.5-fold at pH 2.5. There were also six protein spots that were exclusively present on different pH maps. Further analysis showed that eight of the enhanced proteins, NagA, NagB, PGM, GlmM, LacC, TDP, GALM and PtsI, were involved in carbohydrate catabolism. Moreover, quantitative RT-PCR showed that the mRNA expression levels of dnaK, nagB, galm, estC, tuf and luxS were consistent with changes in protein expression. We postulate that there might be some relationship between differentially expressed proteins and acid tolerance in L. casei Zhang.
耐酸能力是益生菌在通过胃肠道时的一个重要特征。使用二维电泳技术，对一种新的益生菌——干酪乳杆菌 Zhang 进行了蛋白质组学分析，研究其在 30 分钟暴露于低酸应激（pH 2.5 与 pH 6.4）下的变化。在两个 pH 值之间表达发生变化的 33 个蛋白质斑点中，有 22 个在 pH 2.5 时的表达水平比在 pH 6.4 时高 1.5 倍，而有 5 个斑点在 pH 2.5 时的表达水平降低了 1.5 倍。还有 6 个蛋白质斑点仅在不同的 pH 图谱上出现。进一步的分析表明，增强的 8 种蛋白质（NagA、NagB、PGM、GlmM、LacC、TDP、GALM 和 PtsI）参与碳水化合物分解代谢。此外，定量 RT-PCR 显示，dnaK、nagB、galm、estC、tuf 和 luxS 的 mRNA 表达水平与蛋白质表达的变化一致。我们推测，在干酪乳杆菌 Zhang 中，差异表达蛋白与耐酸能力之间可能存在一定的关系。
