一株类志贺邻单胞菌噬菌体生物学特性及全基因组分析

Biological characteristics and genomic analysis of a Plesiomonas shigelloides phage phiP4-7

摘要:

【目的】多重耐药菌株的出现给食品安全带来严重威胁。噬菌体是不同于抗生素的一类重要杀菌因子，对其生物学特性及基因组的研究和分析可为噬菌体的抗菌应用提供依据。【方法】对噬菌体phiP4-7的生物学特性、基因组学、分类学进行研究。【结果】经透射电子显微镜观察，确定phiP4-7头部直径为（50.59±1.68） nm，尾部长度为（76.53±4.90） nm，属于长尾噬菌体科；一步生长曲线结果表明，其潜伏期时间约为25 min，每个感染中心释放的噬菌体数量约为63 PFU/infection center；抑菌曲线结果表明，phiP4-7能够有效地抑制宿主菌的生长。基因组测序组装结果显示，phiP4-7基因组长度为39 825 bp，GC含量为48.67%。通过生物信息学软件对基因组进行注释，发现phiP4-7的基因组上共编码72个蛋白，不编码tRNA基因，未发现已知的耐药基因和毒力基因。比较基因组学和分类学结果显示，将其归类为长尾噬菌体科中的一个新属。【结论】分离得到了一株新类志贺邻单胞菌噬菌体，并对其生物学特性和基因组进行了分析。

Abstract:

[Objective] The emergence of the multidrug resistant bacterial pathogens is posing great threats to food safety. Phages are the important bactericidal factors different from antibiotics. The evidence of phage application can be provided by analyzing the phage biological characteristics and genome. [Methods] In this study, one lytic phage phiP4-7 specific to the strain Plesiomonas shigelloides P4-7 was investigated on its biological characteristics, genome annotations, and taxonomic analysis. [Results] The images of transmission electron microscopy (TEM) showed that the phage has an icosahedral head with a diameter of (50.59±1.68) nm, a noncontractile tail with a length of (76.53±4.90) nm, belonging to the family of Siphoviridae. One-step growth curve suggested that phiP4-7 has a latent period of 25 min and its burst size was about 63 PFU/infection center. Additionally, phiP4-7 can effectively inhibit the growth of the host bacteria. The genome of phiP4-7 has been sequenced, assembled, and curated. It has a total of 39 825 bp with the GC content of 48.67%. Bioinformatic tools reveals that the phiP4-7 genome has 72 protein encoding genes, and no tRNA genes, antibiotic resistance genes, or virulence genes were identified. Comparative genomic and taxonomic analyses indicated that the genome of phiP4-7 showed little homology to any known viruses, and it can be classified as a member of a new genus of the Siphoviridae family. [Conclusion] A new Plesiomonas shigelloides phage was isolated, and its biological characteristics and genome were analyzed.