两株新的金黄色葡萄球菌烈性噬菌体的生物学特性和基因组学研究

以金黄色葡萄球菌为宿主菌，从奶牛场废水样品中分离到两株烈性噬菌体，分别命名为phiSA_BS1和phiSA_BS2。电子显微镜观察显示其头部呈多面体对称，有伸缩性尾部。对这两株噬菌体的一步生长曲线、温度耐受性和pH耐受性进行研究，发现两者均裂解3株金黄色葡萄球菌，但不能裂解1株表皮葡萄球菌。进一步分析它们的全基因组序列，发现phiSA_BS1基因组大小为 142 978 bp，GC含量为 29.80%，预测到201个开放读码框(open reading frame，ORF)，未预测到tRNA基因；phiSA_BS2基因组大小为 149 230 bp，GC含量为 29.61%，预测到210个ORF和1个tRNA基因。系统发育分析表明，这两株噬菌体同属肌尾噬菌体科，属于新的金黄色葡萄球菌噬菌体，可能为治疗金黄色葡萄球菌相关的奶牛乳腺炎提供新的方法。

Biological characteristics and genomics of two new virulent Staphylococcus aureus phages

Two lytic phage strains of Staphylococcus aureus (S. aureus) were isolated from waste water of a dairy farm, and named as phiSA_BS1 and phiSA_BS2. Electronic microscopy showed that both of them were composed of a polyhedral head and a contractible tail. Their one-step growth curve, temperature-tolerance and pH-tolerance were analyzed. They were able to lyse all three strains of S. aureus tested, but failed to lyse a strain of S. epidermidis. Complete genome sequencing and annotation showed that phiSA_BS1 had a genome of 142 978 bp, with 29.80% GC, presumably encoding 201 open reading frames (ORFs), and with no tRNA gene, whereas phiSA_BS2 had a genome of 149 230 bp, with 29.61% GC, presumably encoding 210 ORFs, and with one tRNA gene. Phylogenic analysis indicated that the two phages were members of Myoviridae, and they were two new S. aureus phages. However, they were highly distanced from any other reported phages. These two phage strains may provide new options for the therapy of S. aureus-related bovine mastitis.