The foodborne pathogen Listeria monocytogenes can grow in a wide range of environmental conditions. For the study of the physiology of this organism, several chemically defined media have been developed over the past decades. Here, we examined the ability of L. monocytogenes wildtype strains EGD-e and 10403S to grow under salt and pH stress in Listeria synthetic medium (LSM). Furthermore, we determined that a wide range of carbon sources could support the growth of both wildtype strains in LSM. However, for hexose phosphate sugars such as glucose-1-phosphate, both L. monocytogenes strains need to be pre-grown under conditions, where the major virulence regulator PrfA is active. In addition, growth of both L. monocytogenes strains was observed when LSM was supplemented with the amino acid sugar N-acetylmannosamine (ManNAc). We were able to show that some of the proteins encoded in the operon lmo2795-nanE, such as the ManNAc-6-phosphate epimerase NanE, are required for growth in the presence of ManNAc. The first gene of the operon, lmo2795, encodes a transcriptional regulator of the RpiR family. Using electrophoretic mobility shift assays and quantitative real-time PCR analysis, we were able to show that Lmo2795 binds to the promoter region of the operon lmo2795-nanE and activates its expression.

中文翻译：

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李斯特菌合成培养基中单核细胞增生李斯特菌生长行为的表征

食源性病原体单核细胞增生李斯特菌可以在多种环境条件下生长。为了研究这种生物体的生理学，在过去的几十年里已经开发了几种化学成分确定的培养基。在这里，我们检查了单增李斯特菌野生型菌株 EGD-e 和 10403S 在李斯特菌合成培养基 (LSM)中盐和 pH 胁迫下生长的能力。此外，我们确定多种碳源可以支持两种野生型菌株在 LSM 中的生长。然而，对于磷酸己糖，例如 1-磷酸葡萄糖，两种单核细胞增生利斯特氏菌菌株都需要在主要毒力调节剂 PrfA 活跃的条件下预生长。此外，当 LSM 补充氨基酸糖N-乙酰甘露糖胺 (Man N Ac)时，观察到两种单增李斯特菌菌株的生长。我们能够证明操纵子lmo2795 - nanE中编码的一些蛋白质（例如 Man N Ac-6-磷酸差向异构酶 NanE）是在 Man N Ac存在下生长所必需的。操纵子的第一个基因lmo2795编码 RpiR 家族的转录调节因子。使用电泳迁移率变动分析和定量实时 PCR 分析，我们能够证明 Lmo2795 与操纵子lmo2795 - nanE的启动子区域结合并激活其表达。