FACTORS INVOLVED IN THE INHIBITION OF GROWTH OF SALMONELLA-ENTERITIDIS IN LIQUID EGG-WHITE

This study was designed to investigate the growth potential of Salmone lla enteritidis in liquid egg white at 30 degrees C and to examine the mechanism of egg white resistance to Salmonella growth, We observed a low and variable growth in whole egg white: Salmonella cell counts ro se by 2 log units during the 4 to 6 days of incubation. Treatments to render the egg white components more homogeneous and to facilitate the circulation of nutrients had no effect on the low and variable growth of Salmonella cells. To investigate whether a lack of nutrients or th e presence of Inhibitory factors could explain this low growth, the gr owth of various strains at 30 degrees C in egg white filtrate (egg whi te without protein) was examined. Growth was fast and comparable with growth observed in optimum medium (tryptic soy broth). The addition of 10% egg white to the filtrate decreased the growth of Salmonella ente ritidis to the same level observed in egg white, leading us to conclud e that inhibitory factors, probably proteins, inhibit the growth of S. enteritidis. To determine the role of the different egg white protein s and to identify which of these inhibit S. enteritidis growth, the ef fect of each protein added to the filtrate was evaluated. To test the inhibitory potency of three binding proteins, supplementation with the ir corresponding ligands was also studied. Our study shows that ovotra nsferrin, or iron deficiency resulting from iron binding to ovotransfe rrin, was the major protein or mechanism implicated in the inhibition of the growth of S. enteritidis in egg white.