Food Science and Technology Programme, c/o Department of Chemistry, National University of Singapore, Singapore 117543, Singapore; National University of Singapore (Suzhou) Research Institute, 377 Lin Quan Street, Suzhou Industrial Park, Suzhou, Jiangsu 215123, PR China.
The Nuclear Magnetic Resonance Laboratory, Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore.
Int J Food Microbiol. 2018 Apr 20;271:24-32. doi: 10.1016/j.ijfoodmicro.2018.02.014. Epub 2018 Feb 14.
Bactericidal effects of low concentration electrolysed water (LcEW) on microorganisms are previously well reported; however, the inactivation mechanism of EW is not understood. The lethal and sublethal injuries of L. monocytogenes and L. innocua by EW treatments were determined and the metabolic profile changes for L. innocua were characterised using nuclear magnetic resonance (NMR). Microbial metabolomics approach combined with multivariate data analyses was used to interpret the cellular chemical fingerprints of L. innocua. The relative amount of intracellular reactive oxygen species (ROS) was assayed using 2',7-dichlorodihydrofluorescein diacetate (HDCFDA). The results showed that the proportion of the sublethally injured microbial cells L. monocytogenes and L. innocua increased from 40% to 70% and from 35% to 65%, respectively, when the free available chlorine (FAC) of LcEW increased from 2 to 8 mg/L. Overall, 36 low-molecular-weight metabolic compounds in L. innocua extracts were characterised by NMR spectroscopy. EW perturbation resulted in a drastic and multitude disruption across a wide range of biochemical process including peptidoglycan synthesis, nucleotides biosynthesis and amino acid metabolism. Elevated levels of α-ketoglutarate and succinate implicated the enhanced glutamate decarboxylase (GAD) system and γ-aminobutyric acid (GABA) shunt for the protection against oxidative stress. These findings provided the comprehensive insights into the metabolic response of Listeria to EW oxidative stress and can serve as a basis for better utilisation for sanitisation.
低浓度电解水 (LcEW) 对微生物的杀菌作用先前已有报道，但 EW 的失活机制尚不清楚。本研究通过确定 L. monocytogenes 和 L. innocua 经 EW 处理后的致死和亚致死损伤，并采用核磁共振（NMR）对 L. innocua 的代谢谱变化进行特征描述，来研究 L. innocua 的代谢组学方法。采用多元数据分析结合微生物代谢组学方法，对 L. innocua 的细胞化学指纹进行了分析。采用 2',7-二氯二氢荧光素二乙酸酯（HDCFDA）测定细胞内活性氧（ROS）的相对含量。结果表明，当 LcEW 的游离有效氯（FAC）从 2 增加到 8mg/L 时，L. monocytogenes 和 L. innocua 的亚致死微生物细胞比例分别从 40%增加到 70%和从 35%增加到 65%。总的来说，通过 NMR 光谱鉴定了 36 种 L. innocua 提取物中的低分子量代谢化合物。EW 处理导致广泛的生物化学过程发生剧烈和多种破坏，包括肽聚糖合成、核苷酸生物合成和氨基酸代谢。α-酮戊二酸和琥珀酸水平升高表明谷氨酸脱羧酶（GAD）系统和γ-氨基丁酸（GABA）支路增强，以抵抗氧化应激。这些发现为李斯特菌对 EW 氧化应激的代谢反应提供了全面的见解，并为更好地利用消毒提供了依据。
