Laboratory of Food Microbiology and Hygiene, Department of Food Science and Nutrition, School of the Environment, University of the Aegean, 81400 Myrina, Lemnos, Greece.
Biomolecules. 2021 Mar 8;11(3):397. doi: 10.3390/biom11030397.
Fresh vegetables and salads are increasingly implicated in outbreaks of foodborne infections, such as those caused by , a dangerous pathogen that can attach to the surfaces of the equipment creating robust biofilms withstanding the killing action of disinfectants. In this study, the antimicrobial efficiency of a natural plant terpenoid (thymol) was evaluated against a sessile population of a multi-strain cocktail developed on stainless steel surfaces incubated in lettuce broth, under optimized time and temperature conditions (54 h at 30.6 °C) as those were determined following response surface modeling, and in comparison, to that of an industrial disinfectant (benzalkonium chloride). Prior to disinfection, the minimum bactericidal concentrations (MBCs) of each compound were determined against the planktonic cells of each strain. The results revealed the advanced killing potential of thymol, with a concentration of 625 ppm (= 4 × MBC) leading to almost undetectable viable bacteria (more than 4 logs reduction following a 15-min exposure). For the same degree of killing, benzalkonium chloride needed to be used at a concentration of at least 20 times more than its MBC (70 ppm). Discriminative repetitive sequence-based polymerase chain reaction (rep-PCR) also highlighted the strain variability in both biofilm formation and resistance. In sum, thymol was found to present an effective anti-listeria action under environmental conditions mimicking those encountered in the salad industry and deserves to be further explored to improve the safety of fresh produce.
新鲜蔬菜和沙拉越来越多地与食源性感染有关，例如由李斯特菌引起的感染，李斯特菌是一种危险的病原体，可以附着在设备表面，形成耐消毒剂杀灭作用的坚固生物膜。在这项研究中，评估了一种天然植物萜烯（百里香酚）对不锈钢表面上固定群体的多株李斯特菌鸡尾酒的抗菌效率，在优化的时间和温度条件（30.6°C 下 54 小时）下进行，条件是根据响应面建模确定的，并且与工业消毒剂（苯扎氯铵）进行了比较。在消毒之前，针对每种菌株的浮游细胞确定了每种化合物的最低杀菌浓度（MBC）。结果显示，百里香酚具有较高的杀菌潜力，浓度为 625 ppm（= 4×MBC）可导致几乎无法检测到的活菌（暴露 15 分钟后减少 4 个对数级）。为了达到相同的杀菌效果，苯扎氯铵需要使用至少比其 MBC 高 20 倍的浓度（70 ppm）。区分性重复序列基于聚合酶链反应（rep-PCR）也突出了生物膜形成和耐药性方面的菌株变异性。总之，百里香酚在模拟沙拉行业中遇到的环境条件下对李斯特菌表现出有效的抗李斯特菌作用，值得进一步探索以提高新鲜农产品的安全性。
