Department of Animal Science, Iowa State University, Ames, IA, USA; Interdepartmental Microbiology Graduate Program, Iowa State University, Ames, IA, USA.
Institute for Milk Hygiene, Department for Farm Animals and Veterinary Public Health, University of Veterinary Medicine, Vienna, Austria.
Int J Food Microbiol. 2019 Jun 16;299:39-46. doi: 10.1016/j.ijfoodmicro.2019.03.016. Epub 2019 Mar 29.
Listeria monocytogenes is a food-borne pathogen responsible for the disease listeriosis and is commonly isolated from food and food production facilities. Many L. monocytogenes strains contain plasmids, though the contributions of plasmids to survival in food production environments are unknown. Three L. monocytogenes ST5, ST8, and ST121 strains containing plasmids, which harbor putative stress response genes, were cured of their plasmids. Wildtype (WT) and plasmid-cured strains were exposed to disinfectant, oxidative, heat, acid, or salt stress. After stress exposure, cells were plated for colony forming unit (CFU) counts to determine survivors. L. monocytogenes WT strains exposed to 0.01% (vol/vol) HO, 1% (vol/vol) lactic acid, and 15% (wt/vol) NaCl, pH 5 showed significantly higher counts of survivors compared to the plasmid-cured strains. The number of survivors for the ST5 WT strain exposed to 10 μg/mL benzalkonium chloride (BC) was significantly higher than in the plasmid-cured strain. The ST8 and ST5 strains were exposed to elevated temperature (50° and 55 °C respectively); only the ST5 WT strain had significantly higher numbers of survivors than the plasmid-cured strains. Our data revealed that L. monocytogenes ST5, ST8, and ST121 plasmids contribute to tolerance against elevated temperature, salinity, acidic environments, oxidative stress and disinfectants.
李斯特菌是一种食源性病原体，可导致李斯特菌病，通常从食物和食品生产设施中分离出来。许多李斯特菌菌株含有质粒，但质粒对食品生产环境中生存的贡献尚不清楚。三种李斯特菌 ST5、ST8 和 ST121 菌株含有质粒，这些质粒携带有潜在的应激反应基因，这些质粒被消除了。野生型（WT）和质粒消除的菌株暴露于消毒剂、氧化、热、酸或盐胁迫下。应激暴露后，平板计数法用于计算菌落形成单位（CFU）以确定存活细胞。与质粒消除的菌株相比，WT 菌株暴露于 0.01%（体积/体积）HO、1%（体积/体积）乳酸和 15%（重量/体积）NaCl、pH 5 时，存活细胞的数量明显更高。暴露于 10μg/mL 苯扎氯铵（BC）的 ST5 WT 菌株的存活细胞数量明显高于质粒消除的菌株。ST8 和 ST5 菌株分别暴露于高温（分别为 50°C 和 55°C）；只有 ST5 WT 菌株的存活细胞数量明显高于质粒消除的菌株。我们的数据表明，李斯特菌 ST5、ST8 和 ST121 质粒有助于耐受高温、高盐、酸性环境、氧化应激和消毒剂。
