Isolation and characterization of bacteriophage JC01 against Cronobacter sakazakii

Abstract:

[Background] Cronobacter sakazakii is an emerging food-borne pathogen. The powdered infant formula (PIF) contaminated by this pathogen may cause necrotizing enterocolitis and meningitis in infants, threatening the life of premature or immunocompromised infants. Bacteriophages are well recognized for their antibacterial properties and may be novel biocontrol agents for C.sakazakii and other food-borne pathogenic bacteria. [Objective] To characterize a novel C. sakazakii bacteriophage isolated from sewage and evaluate its antibacterial effects in PIF. [Methods] The double-layer agar method was used to isolate phages, and then the pH stability, thermal stability, host range, one-step growth curve of the isolate were determined. The phage morphology was observed by transmission electron microscopy. Next-generation sequencing was performed for the genome of the phage, and the lysis efficiency was evaluated. [Results] A novel bacteriophage JC01 against C. sakazakii was isolated from sewage. The phage had an icosahedral head and a long non-contractile tail. The genome of JC01 was 61 736 bp in length, containing 76 the open reading frames (ORF) and no drug-resistance gene, virulence gene or tRNA. The phylogenetic analysis and genome comparison indicated that JC01 was a novel phage belonging to the genus Jacunavirus, the class Casjensviridae of the order Caudoviricetes, and its was named as Jacunavirus JC01. The phage was stable at −20 to 40 °C and pH 5.0−9.0 and capable of lysing C. sakazakii in the contaminated PIF. [Conclusion] JC01 appears to be a novel phage against C. sakazakii, and it might be an alternative biocontrol agent for C. sakazakii contamination in food processing and production environments.

Key words:Cronobacter sakazakii;bacteriophages;genome analysis;food safety