Characterization of the role of ybgC in lysozyme resistance of Salmonella Enteritidis. (March 2020)

• Record Type: Journal Article
• Authors: Qin, Xiaojie; Dong, Rui; He, Shoukui; Zhou, Xiujuan; Zhang, Zengfeng; Cui, Yan; Shi, Chunlei; Liu, Yanhong; Shi, Xianming
• Is Part Of: Food control. Volume 109(2020)
• Publication Date: 2020-03
• Subjects: Salmonella Enteritidis -- ybgC -- Lysozyme -- Cell membrane properties -- Gene expression; Food -- Quality -- Periodicals; Food -- Analysis -- Periodicals; Food handling -- Periodicals; Food industry and trade -- Quality control -- Periodicals; Aliments -- Industrie et commerce -- Qualité -- Contrôle -- Périodiques; Aliments -- Qualité -- Périodiques; Aliments -- Analyse -- Périodiques; Hygiène alimentaire -- Périodiques; Food -- Analysis; Food handling; Food -- Quality; Periodicals; Electronic journals; 664.07
• DOI: 10.1016/j.foodcont.2019.106732
• Languages: English
• ISSNs: 0956-7135

Abstract

Abstract: The ybgC gene (encoding for acyl-CoA thioesterase) was shown to play a crucial role in the survival of Salmonella Enteritidis ( S . Enteritidis) in egg white in our previous study. In this study, the resistance mechanisms of S . Enteritidis wild-type, △ ybgC mutant, and △ ybgC -C complemented strains to lysozyme (a major antibacterial component of egg white) were explored by survival ability test, cell membrane characterization, and gene expression analysis. Our results showed that a 6-log reduction was observed with the △ ybgC mutant after incubation in egg white filtrate-lysozyme (FEW-LY) for 24 h, compared to the wild-type and △ ybgC -C complemented strains. Meanwhile, the △ ybgC mutant exhibited a significant increase in outer membrane permeability, along with the alteration from a rod to a spherical shape and the occurrence of cell lysis. Additionally, the amount of C14:0 and C17:0 cyclo fatty acids was decreased, while that of C18:1ω7c and C19:0 cyclo ω8c fatty acids was increased, respectively, in response to lysozyme by the deletion of ybgC . Genes responsible for the synthesis of fatty acids ( fadR, fabBDG, acpP, cfa, and tesAB ), phospholipid ( aas, plsB, and plsC ), and lipid A ( lpxA ) were up-regulated in the △ ybgC mutant after exposure to lysozyme. Taken together, these results indicate that deletion of ybgC induced the expression of membrane lipid composition-related genes probably contributing to alterations in fatty acid and phospholipid composition in S . Enteritidis, which resulted in an increase in outer membrane permeability conducing to a reduced resistance to lysozyme. Moreover, the ybgC gene has potential as a novel molecular target for controlling S . Enteritidis in eggs. Highlights: Gene ybgC confered resistance of S. Enteritidis to lysozyme in egg white filtrate. Membrane permeability was increased in the △ ybgC mutant exposed to lysozyme. Cellular morphology was disrupted in the △ ybgC mutant exposed to lysozyme. Fatty acid composition was altered in the △ ybgC mutant exposed to lysozyme. The expression of membrane lipid composition-related genes was up-regulated.