Characterization Of Lytic Bacteriophage ZG49,Assigned To A New Member Of T7-like Phages Infecting Escherichia Coli

Objectives:Escherichia coli is a gram-negative bacterium belonging to the genus Enterobacteriaceae,mainly in the intestine of humans and animals,and may also be present in the natural environment.Often,Escherichia coli as a normal group of members of the body without damage to the body,but in some special circumstances,such as the body’s immune function decline,through the invasion of invasive access to tissues and organs,can cause a variety of infections.In addition,some pathogenic Escherichia coli can cause infection and outbreaks such as enterotoxigenic Escherichia coli and enteric pathogenic Escherichia coli can be transmitted through the fecal channel,it should cause enough attention.In this study,Escherichia coli phage was isolated and identified to explore the possibility of phage infection in Escherichia coli,which provided the basis for phage therapy for bacterial infection.Methods:1,15 strains of Escherichia coli clinical isolates as a host,with aconventional method,from the sewage separation of a cracked phage,named ZG49.2,the use of sterile inoculation ring,a single plaque to pick,and then inoculated into the suspension of host bacteria,the initial purification and titration of phage,observe the morphology3,to draw its growth curve.Record the latency,outbreak and outbreak of phage growth curve.4.Preparation of phage protein samples by SDS-PAGE electrophoresis and dyeing decolorization5,observe the phage map,phage stability test6,phage genome sequencing and gene function annotation Result:1、15 strains of Escherichia coli clinical isolates as a host,with a conventional method,from the sewage separation of a cracked phage,named ZG49.2、By observing,the morphological characteristics of phage ZG49 are consistent with the end of the virus,the foot virus family phage.The optimal infection number of phage ZG49 was 1.3、The growth curve of ZG49 showed that the latency of ZG49 was30 minutes,the burst period was 30 minutes and the burst volume could reach 200 PFU / ml.4、SDS-PAGE showed four main protein bands,Respectively,50 k Da,45 k Da,30 k Da and 10 k Da.5、The cleavage spectrum analysis showed that phage ZG49 could cleave 6 isolates of Escherichia coli(40% cleavage rate).6、Genome sequencing analysis showed that the genome of phage ZG49 was double-stranded DNA,the size was 39208 bp,and the content of G + C was 49.86%.7、The RAST software was used to predict the genome first,and then to comment on the genome.A total of 46 protein-encoding genes were predicted,ranging from 150 to 3888 bp.No t RNA and r RNA were detected.8、Properdin(ORF 1),primer enzyme(ORF 3),DNA polymerase(ORF 5),homing binding protein(ORF 8)were detected by BLASTp and Inter Pro Scan software.The genomic DNA of ORG 1 was detected by BLASTp and Inter Pro Scan software.(ORF 16),Truncated Protein A(ORF 19),Truncated Protein B(ORF 20),Core Protein(ORF)(ORF 27),DNA assembly protein(ORF 28,30),endopeptidase(ORF 29),DNA-directed RNA polymerase(ORF 37),osteopontin(ORF 27)),DNA ligase(ORF 40),host RNA polymerase inhibitor(ORF 43),single stranded DNA binding protein(ORF 44)and endonuclease(ORF 46).The ZG49 whole genome sequence has been submitted to Gen Bank,accession number: KX669227.Conclusion:In this study,a clinical isolate of Escherichia coli was used as the host strain,and a lyophilized phage was isolated from the environment.The phage ZG49 was named and its biological characteristics were analyzed.According to the morphological characteristics of phage ZG49,phage ZG49 belongs to the end of the virus,short-tail virus phage.The phage ZG49 genome was double-stranded DNA with a length of 39,208 bp and a G + C content of 49.86%.The phage ZG whole genome sequence has been submitted to Gen Bank,accession number:KX669227.