State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China.
International Joint Laboratory on Food Safety, Jiangnan University, Wuxi, China.
Foodborne Pathog Dis. 2021 Aug;18(8):599-606. doi: 10.1089/fpd.2020.2888.
is a global foodborne pathogen that causes human diseases ranging from mild gastroenteritis to severe systemic infections. Recently, antimicrobial blue light (aBL) showed effective bactericidal activity against a variety of bacteria (e.g., ) with varying efficiency. However, the antimicrobial mechanism of aBL has not been fully elucidated. Our previous report showed that the outer membrane (OM) is a key target of aBL. The major component of the OM, lipopolysaccharide (LPS), may play a role in aBL bactericidal effect. Therefore, the influence of LPS truncation on the sensitivity of Typhimurium SL1344 to aBL was investigated for the first time. First, the gene in the SL1344 strain likely involved in linking lipid A to the core region of LPS was inactivated and the influence on LPS structure was verified in the mutant strain SL1344Δ. SL1344Δ showed a significant increase in sensitivity to aBL, and the bactericidal efficiency exceeded 8 log CFU at an aBL dose of 383 J/cm, while that of its parental SL1344 strain approached 4 log CFU. To discover the possible mechanism of higher sensitivity, the permeability of OM was determined. Compared to SL1344, SL1344Δ showed 2.7-fold higher permeability of the OM at 20 J/cm, this may explain the higher vulnerability of the OM to aBL. Furthermore, the fatty acid profile was analyzed to reveal the detailed changes in the OM and inner membrane of the mutant. Results showed that the membrane lipids of SL1344Δ were markedly different to SL1344, indicating that change in fatty acid profile might mediate the enhancement of OM permeability and the increased sensitivity to aBL in SL1344Δ. Hence, we concluded that disruption of in Typhimurium led to the formation of truncated LPS and thus enhanced the permeability of the OM, which contributed to the increased sensitivity to aBL.
是一种全球性的食源性病原体，可引起从轻度肠胃炎到严重全身感染等人类疾病。最近，抗菌蓝光（aBL）对各种细菌（如 ）表现出有效的杀菌活性，但其抗菌机制尚未完全阐明。我们之前的报告表明，外膜（OM）是 aBL 的关键靶标。OM 的主要成分脂多糖（LPS）可能在 aBL 杀菌作用中发挥作用。因此，首次研究了 LPS 截断对 Typhimurium SL1344 对 aBL 敏感性的影响。首先，失活了 SL1344 菌株中可能参与将脂质 A 连接到 LPS 核心区域的 基因，并在突变株 SL1344Δ中验证了 LPS 结构的影响。SL1344Δ对 aBL 的敏感性显著增加，在 aBL 剂量为 383 J/cm 时，杀菌效率超过 8 log CFU，而其亲本 SL1344 菌株则接近 4 log CFU。为了发现更高敏感性的可能机制，测定了 OM 的通透性。与 SL1344 相比，SL1344Δ在 20 J/cm 时 OM 的通透性增加了 2.7 倍，这可能解释了 OM 对 aBL 的更高易感性。此外，还分析了脂肪酸图谱以揭示突变体中 OM 和内膜的详细变化。结果表明，SL1344Δ的膜脂与 SL1344 明显不同，表明脂肪酸图谱的变化可能介导 OM 通透性的增加和 SL1344Δ对 aBL 的敏感性增加。因此，我们得出结论，沙门氏菌中的 基因缺失导致截短的 LPS 形成，从而增强了 OM 的通透性，导致对 aBL 的敏感性增加。
