Bhagwat Arvind A, Young Lynn, Smith Allen D, Bhagwat Medha
Environmental, Microbial, & Food Safety Laboratory, Beltsville Agriculture Research Center, USDA-ARS (USDA/ARS/EMFSL), 10300 Baltimore Ave., B173, Rm. 204, BARC-E, Beltsville, MD, 20705, USA.
National Institutes of Health Library, Division of Library Services, Office of Research Services, National Institute of Health, Building 10, Bethesda, MD, 20892, USA.
Curr Microbiol. 2017 Sep;74(9):1005-1014. doi: 10.1007/s00284-017-1267-1. Epub 2017 Jun 8.
Movement of food-borne pathogens on moist surfaces enables them to migrate towards more favorable niches and facilitate their survival for extended periods of time. Salmonella enterica serovar Typhimurium mutants defective in Osmoregulated periplasmic glucans (OPG) synthesis are unable to exhibit motility on moist surfaces (swarming); however, their mobility in liquid (swim motility) remains unaffected. In order to understand the role of OPG in swarm motility, transcriptomic analysis was performed using cells growing on a moist agar surface. In opgGH deletion mutant, lack of OPG significantly altered transcription of 1039 genes out of total 4712 genes (22%). Introduction of a plasmid-borne copy of opgGH into opgGH deletion mutant restored normal expression of all but 30 genes, indicating a wide-range influence of OPG on gene expression under swarm motility condition. Major pathways that were differentially expressed in opgGH mutants were motility, virulence and invasion, and genes related to the secondary messenger molecule, cyclic di-GMP. These observations provide insights and help explain the pleiotropic nature of OPG mutants such as sub-optimal virulence and competitive organ colonization in mice, biofilm formation, and sensitivity towards detergent stress.
食源性病原体在潮湿表面的移动使它们能够向更适宜的生态位迁移，并有助于它们长时间存活。在渗透调节周质葡聚糖（OPG）合成方面存在缺陷的肠炎沙门氏菌鼠伤寒血清型突变体无法在潮湿表面表现出运动性（群体游动）；然而，它们在液体中的移动性（游泳运动性）不受影响。为了了解OPG在群体运动中的作用，对在潮湿琼脂表面生长的细胞进行了转录组分析。在opgGH缺失突变体中，OPG的缺失显著改变了4712个基因中1039个基因（22%）的转录。将携带opgGH的质粒导入opgGH缺失突变体后，除30个基因外，所有基因的表达恢复正常，这表明在群体运动条件下，OPG对基因表达有广泛影响。在opgGH突变体中差异表达的主要途径包括运动性、毒力和侵袭，以及与第二信使分子环二鸟苷相关的基因。这些观察结果提供了见解，并有助于解释OPG突变体的多效性，如在小鼠中次优的毒力和竞争性器官定殖、生物膜形成以及对洗涤剂胁迫的敏感性。
