Yang Xi, Wu Shuyan, Luo Shuanghua, Weng Xing, Wu Yue, Yu Xia, Huang Xiaodong, Wang Xiaoyuan, Hu Xiaoqing
State Key Laboratory of Food Science and Technology, School of Biotechnology, Jiangnan University, Wuxi, China.
Hopkirk Research Institute, AgResearch Ltd., Palmerston North, New Zealand.
Foodborne Pathog Dis. 2024 Mar;21(3):174-182. doi: 10.1089/fpd.2023.0022. Epub 2023 Dec 19.
, an opportunistic milk-borne pathogen responsible for severe neonatal meningitis and bacteremia, can synthesize yellow pigment (various carotenoids) benefiting for bacterial survival, while little literature was available about the influence of various carotenoids on bacterial resistance to a series of stresses and the characteristics of cell membrane, obstructing the development of novel bactericidal strategies overcoming the strong tolerance of . Thus in this study, for the first time, five carotenogenic genes of BAA-894 were inactivated, respectively, to construct a series of mutants producing various carotenoids and their effects on the cell membrane properties, and resistances to food- and host-related stresses, were investigated systematically. Furthermore, to explore its possible mode of action, comparative lipidomics analysis was performed to reveal the change of lipids that were mainly located at cell membranes. The results showed that five mutants (Δ, Δ, Δ, Δ, and Δ) displayed negligible change in growth rate but higher permeability of the outer membrane and lower fluidity of cell membrane compared to the wild type. Besides, these mutants exhibited poorer ability of biofilm formation and lower resistances to acid, oxidative, osmotic, and desiccation stresses, indicating that different carotenoid composition significantly affected environmental tolerance of . To discover the possible causes, lipidomics analysis of was conducted and more than 500 lipid species belonging to 27 classes had been identified at first. Compared to that of BAA-894, the composition and relative intensity of lipid species in five mutants varied significantly, especially the monounsaturated and biunsaturated phosphatidylethanolamine. The evidence presented in this study demonstrated that the varied composition of carotenoids in significantly altered the lipid profile and intensity, which maybe a crucial means to influencing the characteristics of cell membranes and resistance to environmental stresses.
是一种通过乳汁传播的机会致病菌，可引发严重的新生儿脑膜炎和菌血症，它能合成黄色色素（多种类胡萝卜素）以利于细菌存活，然而关于各种类胡萝卜素对细菌抗一系列应激能力及细胞膜特性的影响，相关文献却很少，这阻碍了克服对其强大耐受性的新型杀菌策略的发展。因此，在本研究中，首次分别使BAA - 894的五个类胡萝卜素生成基因失活，构建了一系列产生不同类胡萝卜素的突变体，并系统研究了它们对细胞膜特性以及对与食物和宿主相关应激的抗性的影响。此外，为探索其可能的作用方式，进行了比较脂质组学分析以揭示主要位于细胞膜上的脂质的变化。结果表明，与野生型相比，五个突变体（Δ、Δ、Δ、Δ和Δ）的生长速率变化可忽略不计，但外膜通透性更高，细胞膜流动性更低。此外，这些突变体表现出较差的生物膜形成能力以及对酸、氧化、渗透和干燥应激的抗性较低，表明不同的类胡萝卜素组成显著影响了的环境耐受性。为找出可能的原因，首先对进行了脂质组学分析，已鉴定出属于27类的500多种脂质种类。与BAA - 894相比，五个突变体中脂质种类的组成和相对强度有显著差异，尤其是单不饱和和双不饱和磷脂酰乙醇胺。本研究提供的证据表明，中类胡萝卜素组成的变化显著改变了脂质谱和强度，这可能是影响细胞膜特性和对环境应激抗性的关键手段。
