Biological characteristics of Klebsiella pneumoniae K7R phage and its resistance mechanism of resistant strains
The aim of this study is to isolate bacteriophages with good bactericidal activity against Klebsiella pneumoniae and explore the resistance mechanism of their resistant strains.In this study,the Siphoviridae phage vB_KpnS_ZH01(P-K7R)was isolated using Klebsiella pneumoni-ae K7R as the host bacteria,with a multiplicity of infection of 0.01,a latent period of about 10 min,a burst rate of 169 PFU/cell,and stable and good bactericidal activity.Whole genome sequen-cing showed that the full length of P-K7R was 52 111 bp and encodes 86 open reading frames.After induction,P-K7R resistant strain K7R-5P was obtained.Although there were no significant differ-ences in morphology,colony morphology and growth curve between K7R-5P and K7R,five differ-ent genes ompC,ompF,N5,N102 and N103 were detected at the transcriptome level.There was a significant difference in the adsorption rate of K7R-5P and K7R to phage,with an adsorption effi-ciency of over 80％for K7R and less than 20％for K7R-5P.Finally,RT-qPCR was utilized to veri-fy the transcriptome results,which showed that the phage resistance of stain P-K7R disappeared after the restoration of gene expression of ompC in K7R-5P,indicating that the ompC gene plays a crucial role in the process of phage P-K7R adsorption of Klebsiella pneumoniae.In this study,a strain of Klebsiella pneumoniae phage P-K7R was obtained,and the mechanism of phage K7R-5P resistance generation in vitro was explored,which lays the foundation for further efficient applica-tion of phage therapy.
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