Abstract: In order to explore a new way to control Salmonella infection,phages with high titer and wide lysis spectrum were isolated in this experiment.Firstly,spot test and efficiency of plating (EOP) test were used to isolate and purify Salmonella phage and determine its lysis titer and lysis spectrum.Then the morphological characteristics of one of the phages with high titer and wide lysis spectrum was further observed by electron microscope,and detected the multiplicity of infection(MOI),one-step growth curve,along with temperature,pH and UV sensitivity.The results showed that the lysis rate of the bacteriophage to different host bacteria was different with lysis titer from 10⁹ to 10¹² PFU/mL.The lysis rate of 32 Salmonella strains detected was 59.4%.It was observed that the phage had a long tail phage with a head diameter of about 70 nm and a tail length of about 140 nm under transmission electron microscope.The best MOI was 0.01 when measured by host of Salmonella Typhimurium ATCC 14028,and one-step growth curve showed that the latent period was 20 min,the burst period was 100 min,and the burst size was 113 PFU/cell.The titer was stable at 10¹⁰ PFU/mL at 40-60 ℃,the titer was above 10⁶ PFU/mL at pH 5.0-13.0,and the titer was still 10⁶ PFU/mL after UV irradiation for 50 min.Therefore,the phage had the characteristics of high effective lysis,wide lysis spectrum,good stability to temperature,pH,and UV,which was in line with the relevant characteristics of phage preparations,and had the potential to be developed as a backup strain for phage preparations.

Key words: Salmonella; phage; isolation and purification; biological characteristics