Properties of Pseudomonas aeruginosa Phage K4 and Its Applications in Food Preservation

Objective: To study phage applications in the control of bacteria contaminations, Pseudomonas aeruginosa phage K4 was characterized for its biological characteristics and inhibition effects of bacterial growth. Methods: One-step growth curve, phage stability, genome sequencing, comparative genomics analysis, and growth inhibition curve were conducted in this work. Results: One-step growth curve showed that phage K4 had a latent phase of 15 min and a burst size of about 85 PFU/infection center, displaying a strong infectivity. Under different MOIs (multiplicity of infection), phage K4 efficiently inhibited the growth of the host cells. Genomic analysis revealed that phage K4 had a genome of 50358 bp with 77 coding sequences and 1 tRNA-Arg gene. Comparative genomics showed that the genome of phage K4 shared an identity of 95.08% with Pseudomonas virus PA11 which belongs to the Paundecimvirus genus of the Zobellviridae family, suggesting that phage K4 might be a new member of the Paundecimvirus genus. In application assays, phage K4 could significantly control the growth of the host cells in sterilized milk and ready-to-eat beef samples along with obvious reproductions of phage K4. In conclusion, the data suggested that phage K4 was a lytic virus that replicated rapidly with relatively high bactericidal activity. Conclusion: The genome of phage K4 did not carry genes for integration, antibiotic resistance, and virulence, appropriately to be selected as a biocontrol agent in the control and prevention of P. aeruginosa contaminations in foods.