阪崎肠杆菌crtZ缺失对细胞特性和环境抗逆性的影响

Influences of crtZ Deletion on Cell Characteristics and Environmental Stress Resistance of Cronobacter sakazakii

摘要:

目的 阪崎肠杆菌（Cronobacter sakazakii，C. sakazakii）是高致死率的奶源性致病菌，在乳品加工中控制难度较大，这归因于其特殊的细胞特性和较强的环境抗逆性。C. sakazakii细胞膜上存在类胡萝卜素，然而其在细胞生理过程中的功能尚未明晰。因此，探究与色素合成相关的β-胡萝卜素羟化酶基因（crtZ）缺失及回补对细胞特性和抗逆性的影响及机制。方法 采用Red同源重组，在C. sakazakii BAA-894（BAA-894）基础上构建BAA-894ΔcrtZ（ΔcrtZ），同时借助pWSK29回补crtZ得到BAA-894ΔcrtZ/pWSK29-crtZ（ΔcrtZ/pWSK29-crtZ），进一步分析各菌株细胞特性和脂肪酸谱。结果 与BAA-894相比，ΔcrtZ细胞膜渗透性增强、流动性减小、生物膜形成减少且环境抗逆性降低，而ΔcrtZ/pWSK29-crtZ变化较小；ΔcrtZ不饱和脂肪酸种类和质量分数增加，而ΔcrtZ/pWSK29-crtZ变化不大。结论 crtZ基因缺失极有可能是影响C. sakazakii细胞特性和环境胁迫耐受性的重要原因。该研究将有助于丰富C. sakazakii的抗逆机制理论和食品安全控制研究。

Abstract:

Objective Cronobacter sakazakii (C. sakazakii), a milk-borne pathogen leading to high mortality, is hard to be controlled in dairy processing due to its special cell characteristics and strong environmental stress resistance. C. sakazakii produces carotenoids which are located in the cell membrane, while there are few studies on the physiological role of C. sakazakii carotenoids. This study aims to explore the effects of β-carotene hydroxylase gene (crtZ) deletion and complementation on cell characteristics and stress resistance and decipher the potential mechanisms.Method Using Red homologous recombination, the BAA-894ΔcrtZ (ΔcrtZ) mutant was constructed from C. sakazakii BAA-894 (BAA-894), and crtZ was complemented with pWSK29 to generate BAA-894ΔcrtZ/pWSK29-crtZ (ΔcrtZ/pWSK29-crtZ). The cellular characteristics and fatty acid profiles of these strains were then analyzed.Result Compared with BAA-894, ΔcrtZ exhibited enhanced outer membrane permeability, reduced membrane fluidity and biofilm formation, and attenuated resistance to various environmental stresses, whereas these changes were diminished in ΔcrtZ/pWSK29-crtZ. In addition, the number and mass fraction of unsaturated fatty acids increased significantly in ΔcrtZ, while they showed no notable changes in ΔcrtZ/pWSK29-crtZ.Conclusion Deletion of crtZ may be a critical factor influencing the cellular characteristics and environmental stress resistance of C. sakazakii. This study contributes to the theoretical understanding of stress resistance mechanisms in C. sakazakii and provides insights for food safety control strategies.