Isolation And Identification Of Stenotrophomonas Maltophilia Phage TS-10 And Studies On The Role Of Bacterial Biofilms

Stenotrophomonas maltophilia is one of the opportunistic pathogens that cause hospital infection.It mainly resides in the human respiratory tract and intestinal tract,and is easy to colonize the skin,conjunctiva,oral respiratory tract and other parts of hospitalized patients.It has a complex drug resistance mechanism,low outer membrane permeability,and is not easy to penetrate to a variety of antibiotics.Faced with the increasingly difficult treatment of Stenotrophomonas maltophilia,phage therapy is increasingly accepted as a natural and green antibacterial method and is returning to people’s field of vision.In this study,clinical isolates of Stenotrophomonas maltophilia were used as host bacteria,a lytic phage TS-10 was isolated from the lake water.phage.It was a typical tadpole-like shape,consisting of an icosahedral head with a diameter of about 110 nm and a retractable helical symmetrical tail.Phage TS-10 had strong host specificity;the optimal multiplicity of infection of phage TS-10 was 0.01,the incubation period was15 min,and the lysis period was 65 min.Phage TS-10 was more sensitive to temperature.Phage TS-10 lost all activity at 30 min at 70℃,and inactivated at 20 min at 80℃.Phage TS-10 maintained a high titer at p H 4-11,Under the condition of p H12,the activity of bacteriophage decreased slightly,and under the condition of p H3,the activity of bacteriophage decreased greatly。The whole genome of phage TS-10 was sequenced and uploaded to Genbank with accession number OK018136.The full-length genome of phage TS-10 was42931 bp,with a GC content of 59.92%.The genome contained 53 ORFs,of which18 were predicted to have known functions and 35 were of unknown functions.According to its function,it was divided into five parts: structural protein module,packaging protein module,replication/recombination protein module,metabolic module and cleavage module;virulence genes and drug resistance genes had not been detected yet.Evolutionary analysis showed that it belonged to the Stenotrophomonas phage,and had the closest evolutionary relationship with the reported Stenotrophomonas phage BUCT598.The effect of bacteriophage TS-10 on biofilm was explored from three indicators:morphological observation,determination of OD value,and viable count,It was found that phage TS-10 had an inhibitory effect on the formation of Stenotrophomonas maltophilia biofilm.It could also effectively lyse the already formed Stenotrophomonas maltophilia biofilm.In conclusion,phage TS-10 has great potential in medical treatment,and it has great possibility to be applied to the development of bacteriophage therapy and bacteriophage preparations in the future.