Abstract

A novel temperate phage, named Hesat, was isolated by the incubation of a dairy strain of Staphylococcus aureus belonging to spa-type t127 with either bovine or ovine milk. Hesat represents a new species of temperate phage within the Phietavirus genus of the Azeredovirinae subfamily. Its genome has a length of 43,129 bp and a GC content of 35.11% and contains 75 predicted ORFs, some of which linked to virulence. This includes (i) a pathogenicity island (SaPln2), homologous to the type II toxin-antitoxin system PemK/MazF family toxin; (ii) a DUF3113 protein (gp30) that is putatively involved in the derepression of the global repressor Stl; and (iii) a cluster coding for a PVL. Genomic analysis of the host strain indicates Hesat is a resident prophage. Interestingly, its induction was obtained by exposing the bacterium to milk, while the conventional mitomycin C–based approach failed. The host range of phage Hesat appears to be broad, as it was able to lyse 24 out of 30 tested S. aureus isolates. Furthermore, when tested at high titer (10⁸ PFU/ml), Hesat phage was also able to lyse a Staphylococcus muscae isolate, a coagulase-negative staphylococcal strain.

Key points

• A new phage species was isolated from a Staphylococcus aureus bovine strain.

• Pathogenicity island and PVL genes are encoded within phage genome.

• The phage is active against most of S. aureus strains from both animal and human origins.

中文翻译：

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乳制品中新型金黄色葡萄球菌噬菌体 Hesa​​t 的分离和表征

摘要

通过将属于 spa 型 t127 的金黄色葡萄球菌乳品 菌株与牛或羊奶一起孵育，分离出一种名为 Hesa​​t 的新型温带噬菌体。 Hesat 代表了Azeredovirinae亚科Phietavirus属中的一种新的温带噬菌体。其基因组长度为43,129 bp，GC含量为35.11%，包含75个预测的ORF，其中一些与毒力相关。这包括 (i) 致病岛 (SaPln2)，与 II 型毒素-抗毒素系统 PemK/MazF 家族毒素同源； (ii) DUF3113 蛋白 ( gp30 )，推测其参与全局阻遏蛋白 Stl 的去阻抑； (iii)PVL的簇编码。宿主菌株的基因组分析表明 Hesa​​t 是一种常驻原噬菌体。有趣的是，它的诱导是通过将细菌暴露于牛奶中来实现的，而传统的基于丝裂霉素 C 的方法则失败了。噬菌体 Hesa​​t 的宿主范围似乎很广，因为它能够裂解 30 种测试的金黄色葡萄球菌分离株中的 24 种。此外，当以高滴度（10 ⁸ PFU/ml）进行测试时，Hesat 噬菌体还能够裂解粘蝇葡萄球菌分离株（一种凝固酶阴性葡萄球菌菌株）。

关键点

• 从金黄色葡萄球菌牛菌株中分离出一种新的噬菌体。

• 致病岛和PVL 基因编码在噬菌体基因组内。

• 噬菌体对大多数动物和人类来源的金黄色葡萄球菌菌株均具有活性。