Biological Characteristics And Genomics Of Enterobacter Aeruginosa Phage

Enterobacter aerogenes(Enterobacteriaceae)is an important opportunistic pathogen that cause hospital-acquired pneumonia,bacteremia,and urinary tract infections.In this study,we isolated a phage of a multi-drug resistant Enterobacter aerogenes,and carryed out related basic research to pave the way for the late phage treatment.The main contents and results are listed as follows:1.Isolation of Enterobacter aerogenes phageA multi-drug resistant Enterobacter aerogenes 3-SP was obtained from hospital.The bacteria information was determined empolying indentification of bacteria and drug resistance analysis.And then the phage of 3-SP from hospitals' sewage,environmental sewage and animal feceswere isolated.Finally a phage named phiEap-2 was obtained,and the phage suspension was prepared and stored in the laboratory.2.Study on the Biological Characteristics of the Enterobacter aerogenes phagephiEap-2 was tadpole-like observed by transmission electron microscopy.The length of protein shell was about 55 nm.The tail length was about 117 nm and diameter was 10 nm,which was not contractible.The phage was found to belong to the long-tailed phage.The growth curve of phage phiEap-2 showed that the incubation period was 20 min and the burst period was about 40 min.PhiEap-2 was sensitive to temperature,which lost its activity in the high temperature treatment(70-80?)but remained stable at low temperature(4?),room temperature(25?)and body temperature(37?).Phage phiEap-2 decreased dramatically at pH <3 or pH = 14.Overall,the survival rate of the phage under alkaline condition was higher than that under acidic condition,indicating that the phage was more resistant to alkali than acid.The host-range experiments showed that the phage had a strong specificity.3.The genomic study of Enterobacter aerogenes phageThe phiEap-2 genome was obtained though extraction and purification,and its genome sequence and annotation information were uploaded to Genbank under the serial number KT287080.PhiEap-2 genome length is 40491 bp.GC content is 51.95%.It belongs to linear double-stranded DNA.After phage genome prediction,62 open reading frames was obtained,of which 23 open reading frames were annotated and 39 open reading frames were annotated as hypothetical proteins.The results showed that the phiEap-2structural gene module had a certain degree of sequence conservation with phage FSL SP-031 and Serratia marcescens phage ETA.Although there were significant differences between phages,the structural gene modules were found at the same position in the genomes of the three phage(phiEap-2,FSL SP-031 and ETA)genomes,indicating that PhiEap-2 is evolutionarily related to Salmonella phage FSL SP-031 and Serratia marcescens phage ETA.