The Analysis On Isolation And Identification,biological Characteristics And Whole Genome Of Chicken-derived Proteus Mirabilis Phage

Proteus mirabilis is closely related to the infection of humans and animals’ gastrointestinal tract,respiratory system,and urinary system.One of the important pathogens of low hatchability.Under the policy of comprehensive restriction of antibiotics in farms,phage therapy is expected to solve the problem of bacterial infections,especially drug-resistant bacterial infections.In this paper,Proteus mirabilis was isolated and identified from dead embryos in a hatchery in Chengdu,and its drug resistance was analyzed.The isolated bacteria was used as the host bacteria to isolate and identify and screen out a Proteus mirabilis phage with high lysis rate,clarify its biological characteristics,and conduct bioinformatics analysis to provide scientific basis for the prevention and control of Proteus mirabilis.The main findings are as follows:1.Isolation and identification of Proteus mirabilis and isolation of their bacteriophagesIn order to understand the infection of Proteus mirabilis in chicken embryos in a hatchery in Chengdu,the yolk fluid of dead embryos was pre-enriched and cultured,and then inoculated into selective medium to isolate Proteus mirabilis.The isolated bacteria were observed by colony morphology and identified by Gram staining.The separation rate of Proteus mirabilis was determined by biochemical identification,gel electrophoresis after PCR amplification of specific genes,and drug susceptibility tests were carried out on the isolated bacteria.Results Twenty-seven strains of Proteus mirabilis were isolated and identified from the yolk fluid of 200 dead embryos,with an isolation rate of 13.5%(27/200).The resistance rate of Nikol,cotrimoxazole and sulfisoxazole reached 100%,and the resistance rate to doxycycline and nalidixic acid exceeded 50%;4 strains of Proteus mirabilis were isolated,and the purified phages were Plaque edges are neat,uniform in size and translucent.The research results showed that the resistance of Proteus mirabilis in the hatchery was serious,and the isolated Proteus mirabilis and its phages provided materials for the prevention and control of Proteus mirabilis infection.2.Identification,biological characteristics and genome-wide bioinformatics analysis of Proteus mirabilis phagesIn this study,one strain with the highest lysis rate was screened from the 4 strains of D.mirabilis isolated and identified above,and it was named Q29.The biological characteristics of Q29 were studied,and the whole genome of the phage was determined for further analysis.its genomic characteristics.The results showed that phage Q29 could lyse 12 of the 27 strains of Proteus mirabilis isolated and identified in this study,with a lysis rate of 44%(12/27);the phage titer was 1.6×1011 PFU/m L;the head diameter was 70 nm,tail length of 90 nm;stable activity at 37℃～55℃,still active at65℃ for 1 h,with thermal stability;stable activity at p H 4～p H 9,with acid-base stability;the best multiplicity of infection(MOI)was 0.001;the incubation period was15 min,the outbreak period was 35 min,and the average lysis amount was 60 PFU/m L;the whole genome was 58664 bp,the GC content was 46.87%,and it did not carry antibiotic genes and did not encode virulence genes.Uploaded to NCBI to obtain The accession number is OM962992;a total of 30 open reading frames(ORFs)were predicted,and the possible functions of the proteins encoded by each ORF were annotated.The phage has potential application potential for controlling Proteus mirabilis infection,providing scientific data for the subsequent development of phage preparations.