Genomic Analysis Of Stenotrophomonas Maltphilia Phage BUCT598 And Studies On Lytic Enzyme

With the excessive use of antibiotics and biological agents,the drug resistance of Stenotrophomonas maltophilia is aggravated.It is an urgent problem to control the harm of nosocomial infection of Stenotrophomonas maltophilia.By studying the biological characteristics of phage and analyzing its genome,we can provide a theoretical basis and method for solving the problem of multiple drug resistance of Stenotrophomonas maltophilia.At the same time,its lysin also plays an important role in the control of Stenotrophomonas maltophilia.In this study,phage BUCT598 was isolated and purified from hospital sewage using Stenotrophomonas maltophilia strain No.826 as the host.According to electron microscope results,it can be inferred that it belongs to the family Podoviridae.When the phages were cultured at MOI=0.01,the latent period was short,only 30 min,and the burst size was165 PFU/cell.In particular,the phage BUCT598 can survive in an extremely wide p H range(p H=1-p H=11),demonstrating excellent tolerance to extremely acidic and alkaline conditions.High throughput sequencing results showed that the genome structure of phage BUCT598 was linear ds DNA with a length of 43,581 bp and GC content of 60%.BLASTn comparison showed that phage BUCT598 had 52% coverage and 76.40%similarity with Stenotrophomonas maltophilia phage BUCT609.Meanwhile,the RAST tool predicted that 55 ORFs were encoded,including 24 ORFs encoding functional proteins and the rest encoding hypothetical proteins.No genes encoding bacterial virulence and antibiotic resistance were found.Recombinant plasmid Lysorf6-pET28a(+)was constructed by homologous recombination and transformed into BL21(DE3)cells.Lysorf6 protein was successfully expressed was successfully expressed at IPTG concentration of 0.1 m M and at 16℃ for 20 h.According to SDS-PAGE results,the relative molecular weight of the protein was about 23 k Da(including His tag),which was consistent with the size of the predicted protein.The change of the number of live bacteria confirmed Lysorf6 was better than the control group.Lysorf6 can lyse 60% of Stenotrophomonas maltophilia strain No.826 with damaged outer membrane.In summary,a phage was successfully isolated from hospital sewage and named BUCT598.Then the biological characteristics and genomic characteristics of this phage were analyzed to provide basic theoretical support for further research on Stenotrophomonas maltophilia phages.At the same time,Lysorf6 can lyse Stenotrophomonas maltophilia strain No.826 with the damaged outer membrane,which is a potential choice for the treatment of multidrug-resistant Stenotrophomonas maltophilia.