Efficacy of a new K3-specific bacteriophage for controlling Klebsiella pneumoniae in milk and its potential to disrupt biofilm formation

Klebsiella pneumoniae (K. pneumoniae) has caused huge economic loss in the dairy industry by inducing mastitis and even endanger public health through contaminated milk products. Suppressing bacterial proliferation in raw milk, particularly in cold settings, is important to preserve milk quality. Owing to increasingly serious antibiotic resistance, bacterial infection has gradually become a difficult matter to settle. Thus, bacteriophages emerge as a potentially effective substitute for antibiotics, garnering renewed interest. Here, we isolated and characterized a new phage, designated P1010, which lyses K3 K. pneumoniae specifically among 23 serotypes. The phage exhibited a latent time of 8 min and produced roughly 101 phages per infected bacteria. Possessing a genome of 44,270 base pairs, the linear double-stranded DNA molecule was devoid of lysogeny, toxin, or tRNA-relevant genes. Of note, P1010 succeeded in significantly suppress bacterial growth in milk both under cold storage condition and room temperature. During the biofilm formation inhibition experiment, OD595 values and viable bacteria counts in the phage treatment groups were significantly reduced. A depolymerase derived from P1010 was identified, possessing a K3 specific enzymatic spectrum. In summary, Klebsiella phage P1010 exhibited bright prospects as biocontrol agents in controlling K. pneumoniae contamination in the dairy industry, offering a viable alternative to antibiotics.