Characterization And Genome Sequence Analysis Of A Lytic Bacteriophage XW-59 Infecting Acinetobacter Baumannii

Acinetobacter baumannii is a non-fermented gram-negative bacillus,which is widely distributed in nature and belongs to the opportunistic pathogen.Clinical data showed that the detection rate of Acinetobacter baumannii was increasing in the infected specimens,and it was widely believed that Acinetobacter baumannii was one of the important pathogens causing infection in the hospital.On the other hand,the emergence of the multidrug-resistant strains of Acinetobacter baumannii and the emergence of the resistant strains caused the decline of antibiotic efficacy.Acinetobacter baumannii,therefore,a serious threat to the hospitalized patients immune function defects(such as the tumor treated with radiotherapy and chemotherapy,patients in the organ transplantation,large area burn patients and patients with various chronic diseases of the elderly).The infection and increasing drug resistance caused by Acinetobacter baumannii have become a public health concern.In recent decades,the use of bacteriophages for drug-resistant bacterial infections has aroused people’s interest.The purpose of this study was to provide a basis for bacteriophage therapy for bacterial infection by studying the biological characteristics of Acinetobacter baumannii pyrolysis phage.The bilayer AGAR method was used to isolate a lytic phage from environmental effluent and named XW-59.By electron microscopy,the morphological features of the phage XW-59 were consistent with Caudovirales Order and Podoviridae Family phage.The best infection complex number of phage XW-59 is 10.A one-step growth curve showed that the incubation period of phage XW-59 was 10 min and the outbreak period was 30 min.Stability test showed that the phage XW-59 at 60 ℃ under the condition of 1 h and in the range of pH4 ~ 10 remain its cracking activity.The genome of the extracted and purified phage XW-59 was submitted to lianchuan biotechnology co.,LTD.(hangzhou,China)for gene sequencing,and the sequencing platform was IlluminaHiSeq PE150.The results showed that the genome of the phage XW-59 was double stranded DNA,which was composed of 40,958 bp,and the content of G+C was 39.42%,and no tRNA was found.GeneMarks software was used to annotate the genome with RAST software.The results showed that the genome of the phage XW-59 contains 50 Coding sequences(Coding sequences,CDSs),of which 13 Coding sequences can predict its function,and 37 Coding sequences are unknown genes.By comparison of BLASTn online software,the phage XW-59 gene sequence was highly homologous with baumannii phage vB_baM_IME200.To sum up,phage XW-59 of Acinetobacter baumannii has good cracking activity,and in-depth study will help future phage genome sequence analysis in the application of Acinetobacter baumannii infection.