Abstract: Bacteriophage TBC-1 was isolated from sewage using Cronobacter sakazakii ATCC25944 as the host. Observation under electron microscope revealed that TBC-1 displayed a contractile tail; the shape of its capsid was an icosahedron. It had a wide host range. The multiplicity of infection (MOI) of the bacteriophage was 0.001. The one-step growth curve showed that its latent time was 20 min; the outbreak period was 50 min; the number of outbreak was 100 PFU/cell. TBC-1 maintained its high titer at 40–50 ℃ and pH 4–10. In addition, C. sakazakii showed stronger lytic ability at higher MOI. The complete genome was 85 313 bp in length and the content of GC was 40.65%. It had 118 protein coding sequences (CDSs) and 24 tRNAs. The bacteriostatic effect of the bacteriophage on C. sakazakii ATCC25944 and ATCCBAA894 in milk products was investigated. It turned out that after incubation at 25 ℃ for 3 h with MOI = 106, both strains at 102 CFU/mL in milk were inhibited to below the detection limit. After incubation at 25 or 37 ℃ for 3 h, ATCCBAA894 was inhibited to below the detection limit; after incubation at 25 ℃ for 3–12 h, ATCC25944 was inhibited to below the detection limit. The results showed that the phage exhibited a wide host range against C. sakazakii and had good bacteriostatic efficacy in both milk and milk powder, demonstrating its potential to be a bio-control agent against C. sakazakii in foods.

Key words: Cronobacter sakazakii; lysis bacteriophage; wide host range; bacteriostatic effect