Characterization of a stress tolerance-defective mutant of Lactobacillus rhamnosus LRB
Characterization of a stress tolerance-defective mutant of Lactobacillus rhamnosus LRB
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DOI：
10.1111/omi.12262
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发表时间：
2019-08-01
影响因子：
3.7
通讯作者：
Biswas, Indranil
中科院分区：
文献类型：
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作者：
Biswas, Saswati;Keightley, Andrew;Biswas, Indranil
鼠李糖乳杆菌是一种乳酸菌，在不同的生态环境中生存，包括人类口腔和胃肠道。L.鼠李糖菌是一种产酸细菌，可产生大量乳酸。该生物体也被认为是耐酸的，因为它可以在长期暴露于酸性环境中存活。对于益生菌如L. rhamnosus，有必要了解这种生物体如何在酸胁迫下生存。在本研究中，我们使用L。以鼠李糖乳杆菌（rhamnosus LRB）为出发菌株，筛选出一株对酸胁迫敏感的自发突变体。该突变体，我们命名为RBM1，也显示出对广泛的压力，包括渗透，热，和其他敏感性。使用全基因组测序，我们绘制了突变菌株中的推定突变。与野生型LRB菌株相比，突变体中似乎发生了三个单核苷酸取代。其中，最相关的突变发生在ftsH基因中，该基因在蛋白质中产生了单个氨基酸的变化。我们进行了比较蛋白质组学研究，以了解胁迫敏感性的分子基础，发现突变株中有15%的蛋白质组发生了改变。我们的研究表明，自发突变体的产生，在L。鼠李糖定殖可以显著影响细菌生理学和在胁迫条件下的存活。
Lactobacillus rhamnosus is a lactic acid bacterium that survives diverse ecological niches, including the human oral cavity and gastrointestinal tract. L. rhamnosus is an acidogenic bacterium that produces copious amounts of lactic acid. The organism is also considered as aciduric, since it can survive prolonged exposure to an acidic environment. For a probiotic bacterium such as L. rhamnosus, it is necessary to understand how this organism survives acid stress. In this study we used L. rhamnosus LRB to isolate one spontaneous mutant that was sensitive to acid stress. The mutant, which we named RBM1, also displayed sensitivity to a wide range of stresses including osmotic, thermal, and others. Using whole genome sequencing, we mapped the putative mutations in the mutant strain. It appears that three single nucleotide substitutions occurred in the mutant as compared to the wild-type LRB strain. Among those, the most relevant mutation occurred in the ftsH gene that created a single amino acid change in the protein. We performed a comparative proteomic study to understand the molecular basis for stress sensitivity and found that similar to 15% of the proteome is altered in the mutant strain. Our study suggests that generation of spontaneous mutants during L. rhamnosus colonization could drastically affect bacterial physiology and survival under stress conditions.