Abstract: The current study aims to provide experimental data and references for the development of Salmonella specific antibacterial agents. Here, we isolated a Salmonella phage from chicken farm sewage and studied its biological characteristics and genomics. The results showed that Salmonella phage S5 was isolated. Transmission electron microscopy showed that the phage was a long-tailed phage with a head diameter of about 50 nm and a tail length of about 200 nm. Its head was icosahedral symmetrical, belonging to Caudovirales, Siphoviridae. The phage has a lysis rate of 75% against 20 strains of Salmonella, with a titer of 8×10⁹ PFU·mL^-1. The phage titer remained basically unchanged at the temperature from 30 to 60℃ for 30 min or 1 h, with little effect on phage activity at pH4.0-11.0. The optimal MOI of phage was 0.000 1. The one-step growth curve showed that its titer remained basically unchanged within 5 min incubation period after infection with the host bacteria. The outbreak period was about 95 min, and the average lysate was 50 PFU·cell^-1. Phage S5 was a double-stranded DNA virus. The genome was 72 519 bp in length, and the GC content was 39.45%. It contained 9 types of tRNAs and 109 predicted ORFs. No harmful factors such as bacterial virulence factors had been found. Salmonella virulent phage S5 has good lysis effect, strong adaptability to the environment and clear genetic background. It is expected to become an alternative product of antibiotics for the prevention and control of Salmonella.

Key words: Salmonella, phage, biological characteristics, bioinformatics analysis, genome