Comparative Analysis of Listeria monocytogenes Plasmids and Expression Levels of Plasmid-Encoded Genes during Growth under Salt and Acid Stress Conditions
Comparative Analysis of Listeria monocytogenes Plasmids and Expression Levels of Plasmid-Encoded Genes during Growth under Salt and Acid Stress Conditions
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DOI：
10.3390/toxins11070426
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发表时间：
2019-07-01
期刊：
影响因子：
4.2
通讯作者：
Wang, Siyun
中科院分区：
文献类型：
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作者：
Hingston, Patricia;Brenner, Thomas;Wang, Siyun
已知单核增生李斯特菌菌株含有对消毒剂、重金属和抗生素具有抗性的质粒；然而，关于质粒如何影响单核增生乳杆菌耐受食物相关压力的能力的研究很少。为了研究这一点，我们比较了一文库（n = 93）个单核增生乳杆菌的质粒序列。根据repA的系统发育将质粒序列分为G1和G2两组。观察到26种独特的质粒类型，其中13种属于两个基于repa的组。G1质粒体积显著小于G2质粒（p < 0.05），但含有较多的基因多样性。在来自瑞士和加拿大的26个菌株和各种血清型中观察到最常见的G1质粒（57,083 bp）。定量PCR （qPCR）结果显示，在盐（6% NaCl）和酸（pH 5）条件和盐胁迫条件下，含有NADH过氧化物酶、镉atp酶、多铜氧化酶和ClpL伴侣蛋白编码基因的质粒在盐胁迫条件下生长，以及渗透转运蛋白ProW在盐胁迫条件下的诱导作用为b> 2倍。质粒固化菌株与野生型菌株在耐盐性和耐酸性方面无差异。这项工作强调了食物相关的单核增生乳杆菌菌株中特定质粒类型的丰富程度，G1和G2质粒的独特特性，以及质粒对单核增生乳杆菌对食物相关胁迫的耐受性的可能贡献。
Listeria monocytogenes strains are known to harbour plasmids that confer resistance to sanitizers, heavy metals, and antibiotics; however, very little research has been conducted into how plasmids may influence L. monocytogenes' ability to tolerate food-related stresses. To investigate this, a library (n = 93) of L. monocytogenes plasmid sequences were compared. Plasmid sequences were divided into two groups (G1 and G2) based on a repA phylogeny. Twenty-six unique plasmid types were observed, with 13 belonging to each of the two repA-based groups. G1 plasmids were significantly (p < 0.05) smaller than G2 plasmids but contained a larger diversity of genes. The most prevalent G1 plasmid (57,083 bp) was observed in 26 strains from both Switzerland and Canada and a variety of serotypes. Quantitative PCR (qPCR) revealed a > 2-fold induction of plasmid-contained genes encoding an NADH peroxidase, cadmium ATPase, multicopper oxidase, and a ClpL chaperone protein during growth under salt (6% NaCl) and acid conditions (pH 5) and ProW, an osmolyte transporter, under salt stress conditions. No di ff erences in salt and acid tolerance were observed between plasmid-cured and wildtype strains. This work highlights the abundance of specific plasmid types among food-related L. monocytogenes strains, the unique characteristics of G1 and G2 plasmids, and the possible contributions of plasmids to L. monocytogenes tolerance to food-related stresses.