Abstract: 【Objective】 The purpose of this study was to explore the bacteriophage biological control method for Staphylococcus aureus induced bovine mastitis.【Method】 A strain of bacteriophage specific for Staphylococcus aureus Sau2703 was isolated and purified from cow feces and wastewater using a double-layer agar plate culture method.The titer,ultrastructure and optimal multiplicity of infection were studied.The one-step growth curve of bacterio phage was drawn,and its thermal stability,pH stability,UV sensitivity and fission spectrum were studied.【Result】 A specific bacteriophage of Staphylococcus aureus Sau2703 from bovine mastitis was successfully isolated and named as PhageSau2703.The titer of bacteriophage PhageSau2703 was as high as 4.62×10¹⁵ PFU/mL.Under transmission electron microscopy,the head of PhageSau2703 was icosahedral with a diameter of approximately 71 nm and an non contracting long tail,measuring 106 nm in length and 11 nm in diameter.The optimal multiplicity of infection of PhageSau2703 was 0.001,PhageSau2703 had high thermal stability and still exhibited low activity after being treated at 90 ℃ for 90 min.PhageSau2703 was stable at pH 3.0-8.0,and the tolerance to acidic environments was higher than that to alkaline environments.Ultraviolet radiation had little effect on the activity of PhageSau2703.The incubation period of PhageSau2703 was about 20 min,the outbreak period was about 50 min,and the cleavage volume was about 112 PFU/cell.The cleavage rate of bovine mastitis associated Staphylococcus aureus was 48.5%.The host spectrum of PhageSau2703 was wide.【Conclusion】 Bacteriophage PhageSau2703 had high titer,wide spectrum of fission bacteria,and strong tolerance to temperature,pH and UV light.It had the potential to be developed as a Staphylococcus aureus bacterio phage biological agent for the prevention and treatment of bovine mastitis.

Key words: bovine mastitis; Staphylococcus aureus; bacteriophage