Wałecka E, Molenda J, Bania J
Department of Food Hygiene and Consumer Health Protection, Faculty of Veterinary Medicine, Wrocław University of Environmental and Life Sciences, Norwida 31, 50-375 Wrocław, Poland.
Pol J Vet Sci. 2009;12(4):575-9.
Listeria monocytogenes, a significant food-borne pathogen, must defy a variety of conditions encountered in the food environment and during the infection process. In reaction to adverse conditions, the bacteria significantly change their metabolism, inducing a stress response which is mediated by a range of alternative sigma factors. The extent of the response to stress was shown to vary in the L. monocytogenes population. According to recent evidence a major L. monocytogenes alternative sigma factor, designated sigma B (sigma B), regulates some virulence genes in response to stress, which supports an older hypothesis that stress-resistant strains should be more pathogenic. The induction of sigma B-dependent genes may also be important from the point of view of food hygiene. It seems that stress response activation can paradoxically enhance resistance to agents used in food preservation. Therefore, monitoring the expression of sigma B-dependent genes can serve as a useful marker to assess the innate resistance of L. monocytogenes strains. This knowledge will allow the design of new methods with sequential preservation steps that could inactivate the bacteria without inducing their stress response.
单核细胞增生李斯特菌是一种重要的食源性病原体，它必须抵御在食品环境以及感染过程中遇到的各种条件。面对不利条件时，这种细菌会显著改变其新陈代谢，引发由一系列替代西格玛因子介导的应激反应。研究表明，单核细胞增生李斯特菌群体对应激的反应程度存在差异。根据最近的证据，一种主要的单核细胞增生李斯特菌替代西格玛因子，即西格玛B（σB），会在应激时调节一些毒力基因，这支持了一个较早的假说，即抗应激菌株应该更具致病性。从食品卫生的角度来看，σB依赖基因的诱导也可能很重要。应激反应的激活似乎反而能增强对食品保鲜所用试剂的抗性。因此，监测σB依赖基因的表达可以作为评估单核细胞增生李斯特菌菌株固有抗性的有用指标。这一知识将有助于设计新的方法，通过连续的保鲜步骤来灭活细菌，同时又不会诱导其应激反应。
