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Understanding the relationship between antibacterial activity and iron-restriction mechanisms in egg-white

Abstract : Salmonella Enteritidis is the most prevalent food-borne pathogen associated with egg-related outbreaks in the European Union. In order to colonise eggs, S. Enteritidis must resist the powerful anti-bacterial activities of egg white (EW). Possibly, the major EW antibacterial property is iron restriction, which results from the presence of the Fe3+-binding protein, ovotransferrin. To circumvent iron restriction, S. Enteritidis synthesise two types of catecholate siderophores, enterobactin and salmochelin, that can chelate iron from host iron-binding proteins. However, EW contains a lipocalin (Ex-FABP) that is known to bind enterobactin. Two other lipocalins, Cal-γ and α1-ovoglycoprotein, are found in EW but their siderophore-binding potential was yet to be explored The aim of this project was to study the antimicrobial activity of three EW lipocalins through sequestration of bacterial siderophores synthesised by S. Enteritidis. Among those lipocalins, Cal-γ and α1-ovoglycoprotein were shown to bind neither enterobactin nor salmochelin. Further, it was confirmed that Ex-FABP binds only enterobactin and not salmochelin. In standard growth media, S. Enteritidis escaped Ex-FABP-mediated growth inhibition thanks to salmochelin synthesis. However, no clear antibacterial activity was observed for Ex-FABP in EW. This surprising observation might be correlated with the weak growth of S. Enteritidis in EW and a lack of requirement for siderophores in persistence.
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Contributor : Anne Giboulot <>
Submitted on : Tuesday, October 13, 2020 - 10:42:29 AM
Last modification on : Wednesday, October 14, 2020 - 3:37:25 AM


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  • HAL Id : tel-02965297, version 1



Louis Alex Julien. Understanding the relationship between antibacterial activity and iron-restriction mechanisms in egg-white. Food and Nutrition. Institut Agro Rennes, 2020. English. ⟨tel-02965297⟩



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