噬菌体vB_KpnP_QH2的生物学特性和基因组分析

Biological characteristics and genome analysis of novel phage vB_KpnP_QH2

目的对从医院污水中分离筛选的特异裂解多重耐药肺炎克雷伯菌的噬菌体vB_KpnP_QH2(简称QH2)进行生物学特性和基因组信息分析。方法将从医院污水中获得噬菌体QH2用琼脂双层平板法分离纯化,测定QH2生物学特性,用电镜观察其形态大小;通过测序得到QH2全基因组信息并进行注释和分析。结果QH2属于Slopekvirinae亚科,Drulisvirus属,有尾噬菌体;QH2裂解宿主菌可形成有晕环的噬菌斑;QH2的最佳感染复数为0.00001;其感染潜伏期为5 min,爆发期为15 min,20 min后进入稳定期,裂解量为2.8×10^(9)pfu/cell。QH2基因组全长43083 bp,为双链DNA,GC含量53.88%;预测并注释52个开放阅读框,不包含tRNA结构、毒力因子和耐药基因;序列分析显示QH2的ORF12和ORF13编码裂解细菌相关蛋白。结论从医院污水中分离筛选的QH2能特异裂解多重耐药肺炎克雷伯菌,其生物学特性稳定、安全,为研究噬菌体与宿主间的相互作用及多重耐药细菌感染的治疗提供实验材料。

Objective Biological characteristics and genomic information analysis of bacteriophage vB_KpnP_QH2(abbreviated as QH2),which is specifically lytic to multiple drug-resistant Klebsiella pneumoniae isolated and screened from hospital sewage.Methods The agar double-layer plate method was used to isolate and purify the bacteriophage QH2 obtained from hospital sewage,and the biological characteristics of QH2 were determined.The morphological observation was conducted to analyze its shape and size by electron microscopy.The QH2 genome was annotated and analyzed by sequencing technology.Results QH2 has an icosahedral head and a retractable tail.It belongs to a tailed phage species of the genus Slopekvirinae,subfamily Drulisvirus,and has a close evolutionary relationship with Klebsiella phage VLC1.QH2 lysis of the host bacteria can form bacteriophage plaques with halo rings.The optimal multiplicity of infection is 0.0001,the one-step growth curve revealed that phage QH2 had an infection duration of 40 minutes,5 minutes latent period,and a highly specific to host strain,with a lysis amount is 2.8×10^(9)pfu/cell.The genome of QH2 is 43083 base pairs,double-stranded DNA(dsDNA),with a G+C content of 53.88%;It contains 52 open reading frames that were predicted and annotated,not including tRNA,virulence factors,and antibiotic resistance genes.Sequence analysis showed that ORF12 and ORF13 of QH2 encode bacteriolytic-related proteins.Conclusion QH2,which is specifically lytic to multiple drug-resistant Klebsiella pneumoniae isolated and screened from hospital sewage,has stable and safe biological characteristics,providing experimental materials for the study of the interaction between bacteriophages,their hosts,and the treatment of multiple drug-resistant bacterial infections.