He Shoukui, Zhan Zeqiang, Shi Chunlei, Wang Siyun, Shi Xianming
MOST-USDA Joint Research Center for Food Safety, School of Agriculture and Biology, State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai 200240, China.
Food, Nutrition and Health, Faculty of Land and Food Systems, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
Foods. 2022 Jul 27;11(15):2237. doi: 10.3390/foods11152237.
The survival of Enteritidis in the food chain is relevant to its biofilm formation capacity, which is influenced by suboptimal environmental conditions. Here, biofilm formation pattern of this bacterium was assessed in the presence of ethanol at sub-minimal inhibitory concentrations (sub-MICs) by microtiter plate assays, cell characteristic analyses, and gene expression tests. It was observed that ethanol at subinhibitory concentrations (1/4 MIC, 2.5%; 1/2 MIC, 5.0%) was able to stimulate biofilm formation in Enteritidis. The OD value (optical density at 595 nm) used to quantify biofilm production was increased from 0.14 in control groups to 0.36 and 0.63 under 2.5% and 5.0% ethanol stresses, respectively. Ethanol was also shown to reduce bacterial swimming motility and enhance cell auto-aggregation ability. However, other cell characteristics such as swarming activity, initial attachment and cell surface hydrophobicity were not remarkedly impacted by ethanol. Reverse transcription quantitative real-time PCR (RT-qPCR) analysis further revealed that the gene belonging to a quorum-sensing system was upregulated by 2.49- and 10.08-fold in the presence of 2.5% and 5.0% ethanol, respectively. The relative expression level of other biofilm-related genes (, , , and ) and sRNAs (ArcZ, CsrB, OxyS, and SroC) did not obviously change. Taken together, these findings suggest that decrease in swimming motility and increase in cell auto-aggregation and quorum sensing may result in the enhancement of biofilm formation by Enteritidis under sublethal ethanol stress.
肠炎沙门氏菌在食物链中的存活与其生物膜形成能力相关，而生物膜形成能力受次优环境条件影响。在此，通过微量滴定板试验、细胞特性分析和基因表达测试，评估了该细菌在亚最小抑菌浓度（亚 MIC）乙醇存在下的生物膜形成模式。观察到亚抑制浓度（1/4 MIC，2.5%；1/2 MIC，5.0%）的乙醇能够刺激肠炎沙门氏菌形成生物膜。用于量化生物膜产生的 OD 值（595 nm 处的光密度）在对照组中为 0.14，在 2.5%和 5.0%乙醇胁迫下分别增加到 0.36 和 0.63。乙醇还显示出降低细菌的游动性并增强细胞自聚集能力。然而，其他细胞特性，如群游活性、初始附着和细胞表面疏水性，并未受到乙醇的显著影响。逆转录定量实时 PCR（RT-qPCR）分析进一步表明，在存在 2.5%和 5.0%乙醇的情况下，属于群体感应系统的基因分别上调了 2.49 倍和 10.08 倍。其他生物膜相关基因（、、、和）和 sRNA（ArcZ、CsrB、OxyS 和 SroC）的相对表达水平没有明显变化。综上所述，这些发现表明，在亚致死乙醇胁迫下，游动性降低、细胞自聚集增加和群体感应增强可能导致肠炎沙门氏菌生物膜形成增强。
