环境因素促进单增李斯特菌生物被膜的形成

本实验研究了在营养正常和贫瘠状态下,环境因素包括p H值、氯化钠、常见碳水化合物及危险罗尔斯通氏菌对单增李斯特菌生物被膜形成的影响,并使用激光扫描共聚焦显微镜(Confocal laser scanning microscope,CLSM)观察单增李斯特菌和危险罗尔斯通氏菌单、双菌种生物被膜。结果表明:弱酸、碱性条件、低浓度的氯化钠以及危险罗尔斯通式菌能显著促进单增李斯特菌形成生物被膜,但与营养正常状态相比,营养贫瘠状态下的生物被膜形成量降低。几种常见碳水化合物(葡萄糖、蔗糖、木糖醇、半乳糖及魔芋精粉)也有一定的促进作用,特别是木糖醇和魔芋精粉,引起的增长率分别高达75.00%和96.67%。CLSM结果表明,单增李斯特菌和危险罗尔斯通氏菌生物被膜的空间结构不同,但活菌数都比较多。致病菌生物被膜的形成会对食品安全构成巨大威胁,而很多环境因素又有增强生物被膜形成的作用,应引起食品生产等行业的关注。

Formation of Listeria monocytogenes Biofilm Promote by Environmental Factors

The effects of environmental factors including pH, NaCl, common carbohydrates and an environmental bacteria (Ralstonia insidiosa) on the formation of biofilms by Listeria monocytogenes in normal nutrient and nutrient-poor conditions were investigated. The activity and structure of the single and double strain biofilms by Listeria monocytogenes and Ralstonia insidiosa were observed using Confocal laser scanning microscope (CLSM).The results showed that weak acid, alkaline conditions, low concentration of NaCl and Ralstonia insidiosa could significantly promote the formation of biofilm by Listeria monocytogenes. However, compared with that in normal nutrient, biofilm formation in the nutrient-poor condition was reduced. Several kinds of carbohydrates commonly found in foods (glucose, sucrose, xylitol, galactose and konjac powder) also have a certain promoting effect, especially xylitol and konjac flour, which could cause growth rates up to 75.00% and 96.67%, respectively. The results of CLSM indicated that the biofilm of Listeria monocytogenes and Ralstonia insidiosa were different, but the number of viable cells was relatively high. The formation of biofilms by pathogenic bacteria had a great threat to food safety, and many environmental factors had the effect of enhancing the formation of biofilms, which should cause concern in industries such as food production.