一株烈性沙门氏菌噬菌体的生物学特性及基因组分析

Biological Characterization and Genome Analysis of a Lytic Phage Infecting Salmonella

随着抗生素耐药问题的日益加重,使得致病菌的生物防治愈发困难,新型抗菌剂的研发迫在眉睫。使用噬菌体控制致病菌重新获得了极大关注。为获取具有防治沙门氏菌潜力的噬菌体,采用双层琼脂平板法从河水中分离出一株烈性噬菌体PSM6,在肠炎沙门氏菌的菌苔可形成直径约1.5 mm-2 mm的透亮均匀的噬菌斑;具有宽裂解谱,可裂解多种血清型沙门氏菌、部分大肠杆菌和宋内志贺氏菌;最佳感染复数为0.01;繁殖活性强,潜伏期约20 min,爆发量约56 PFU/cell;在40-60℃、pH=5-10时,效价较为稳定。基因组核酸为双链DNA,基因组大小为90730 bp,G+C含量为39.57%,有133个开放阅读框,含有holin-lysin裂解系统,未发现毒力因子相关基因和抗生素抗性基因。透射电镜观察和基因组测序均显示PSM6属于肌尾噬菌体科。

With the situation of antibiotic resistance becoming more and more serious,it is increasingly difficult to prevent and cure pathogenic bacteria,thus research and development of new antibacterial agents is urgent.The use of bacteriophages to control pathogenic bacteria has received huge attentions.In order to obtain bacteriophages with potential applications in the biological control of Salmonella,a virulent phage PSM6 was isolated from river water by double-layer agar plate method,and transparent and uniform plaques with diameters of about 1.5-2 mm were formed on the lawn of Salmonella enteritidis.Phage PSM6 showed lytic activities on Salmonella of multiple serotypes,some Escherichia.coli strains and Shigella sonnei,indicating a broad-spectrum lytic activity.Phage PSM6 showed the maximal lytic activity to Salmonella with a MOI of 0.01.It demonstrated strong reproductive activity,of which the incubation period was about 20 min and the outbreak amount was about 56 PFU/cell.Phage PSM6 presented a good stability in 40-60℃and kept a stable titer at pH5-10.The genome nucleic acid was double-stranded DNA.The genome was of 90730 bp with a G+C content of 39.6%,133 ORFs and the holin-lysin lysis system,did not contain known virulence-associated and antibiotic resistance genes.Phage PSM6 should belong to Myoviridae according to the results of transmission electron microscopy and genome sequencing.