Changes in the antimicrobial potential of egg albumen during the early stages of incubation and its impact on the growth and virulence response of Salmonella Enteritidis

Abstract

The antimicrobial activity of egg albumen has been widely documented. However, the changes in the chemical nature and antimicrobial activity of egg albumen and the way it controls bacteria during the incubation period have not up to now been understood. The purpose of the present investigation was to analyze the antimicrobial potential of egg albumen during early incubation stages (0–5 days). The changes in ovotransferrin and lysozyme content in egg albumen were quantified via high performance liquid chromatography (HPLC). The results showed that the increase in concentration of ovotransferrin in egg albumen was closely related to the time of incubation, but that of lysozyme remained substantially unchanged and was very similar to that of the non-incubated eggs. The iron ion binding capacity and specific lysozyme activity of the egg albumen during early stages of incubation was also investigated. The changes occurring in egg albumen during early incubation could influence the growth of Salmonella Enteritidis. Very little difference was observed in the virulence response of Salmonella Enteritidis to egg albumen collected at different incubation periods by using the expression of hilA gene as an indicator. Since the first few days of incubation are likely to place heavy demands on the immune capacities of the egg, due to the defenceless immune system of the developing embryo, the changes in antimicrobial activity in egg albumen widen our understanding of the innate immune mechanism of the fertilized egg during its early embryonic development.