This in vitro experiment was designed to study the inhibitory effect of specific (sIgY) and noecific (nsIgY) egg yolk antibody powders on the growth of Staphylococcus aureus, as one of the most important staphylococcus serotypes. To produce antibody powder, 16 Leghorn hens at 40 weeks of age were immunized by vaccine derived from S.aureus and after collecting the eggs for a period of 8 weeks, IgY was isolated and lyophilized with polson method. The concentrations of total IgY and protein in the water soluble fraction (WSF), serum and antibody powder were weekly evaluated during the course of immunization. Inhibitory effect of different levels of nsIgY and sIgY on the growth of Staphylococcus aureus , was tested over a period of 6 hours (the end of the exponential growth phase) in the presence of 2×10 9 CFU/ml bacteria. The specific activity of IgY against S.aureus in serum and egg increased in the day of 7 after the first injection and reached their high levels at last days. The administration of 200 mg sIgY powder markedly (P 0/05) reduced the bacterial count during incubation hours of 4 and 6. Using this level of sIgY could significantly decrease 1/20 log CFU/ml compared with that in control group. Therefore, the results at this study showed S.aureus has a notable potential to produce high levels of antibody in laying white leghorn hens for a long period of time. In addition, polson method is an effective way to obtain remarkable purity sIgY antibody with high efficiency and long term production. Keywords : Egg Yolk Antibody, Staphylococcus aureus , IgY Purification, Cultivating bacteria
