Department of Food and Animal Biotechnology, Department of Agricultural Biotechnology, Research Institute for Agriculture and Life Sciences, and Center for Agricultural Biomaterials, Seoul National University, Seoul, South Korea.
Appl Environ Microbiol. 2012 Jan;78(1):58-69. doi: 10.1128/AEM.06231-11. Epub 2011 Oct 21.
Salmonella enterica and Escherichia coli O157:H7 are major food-borne pathogens causing serious illness. Phage SFP10, which revealed effective infection of both S. enterica and E. coli O157:H7, was isolated and characterized. SFP10 contains a 158-kb double-stranded DNA genome belonging to the Vi01 phage-like family Myoviridae. In vitro adsorption assays showed that the adsorption constant rates to both Salmonella enterica serovar Typhimurium and E. coli O157:H7 were 2.50 × 10⁻⁸ ml/min and 1.91 × 10⁻⁸ ml/min, respectively. One-step growth analysis revealed that SFP10 has a shorter latent period (25 min) and a larger burst size (>200 PFU) than ordinary Myoviridae phages, suggesting effective host infection and lytic activity. However, differential development of resistance to SFP10 in S. Typhimurium and E. coli O157:H7 was observed; bacteriophage-insensitive mutant (BIM) frequencies of 1.19 × 10⁻² CFU/ml for S. Typhimurium and 4.58 × 10⁻⁵ CFU/ml for E. coli O157:H7 were found, indicating that SFP10 should be active and stable for control of E. coli O157:H7 with minimal emergence of SFP10-resistant pathogens but may not be for S. Typhimurium. Specific mutation of rfaL in S. Typhimurium and E. coli O157:H7 revealed the O antigen as an SFP10 receptor for both bacteria. Genome sequence analysis of SFP10 and its comparative analysis with homologous Salmonella Vi01 and Shigella phiSboM-AG3 phages revealed that their tail fiber and tail spike genes share low sequence identity, implying that the genes are major host specificity determinants. This is the first report identifying specific infection and inhibition of Salmonella Typhimurium and E. coli O157:H7 by a single bacteriophage.
肠炎沙门氏菌和大肠杆菌 O157:H7 是主要的食源性致病菌，可导致严重疾病。分离并鉴定了一种能有效感染肠炎沙门氏菌和大肠杆菌 O157:H7 的噬菌体 SFP10。SFP10 含有一个 158kb 的双链 DNA 基因组，属于 Vi01 噬菌体样科 Myoviridae。体外吸附实验表明，该噬菌体对肠炎沙门氏菌血清型鼠伤寒和大肠杆菌 O157:H7 的吸附常数分别为 2.50×10⁻⁸ml/min 和 1.91×10⁻⁸ml/min。一步生长实验表明，SFP10 的潜伏期（25min）较短，爆发量较大（>200PFU），表明其能有效感染宿主并具有溶菌活性。然而，在肠炎沙门氏菌和大肠杆菌 O157:H7 中观察到对 SFP10 的抗性差异发展；噬菌体不敏感突变体（BIM）频率分别为肠炎沙门氏菌 1.19×10⁻² CFU/ml 和大肠杆菌 O157:H7 4.58×10⁻⁵ CFU/ml，表明 SFP10 应该能够有效控制大肠杆菌 O157:H7，而对 SFP10 抗性病原体的出现则应保持最小，但对肠炎沙门氏菌可能效果不佳。肠炎沙门氏菌和大肠杆菌 O157:H7 中 rfaL 的特异性突变表明 O 抗原是两种细菌的 SFP10 受体。SFP10 的基因组序列分析及其与同源沙门氏菌 Vi01 和志贺氏菌 phiSboM-AG3 噬菌体的比较分析表明，它们的尾纤维和尾刺基因的序列同一性较低，这表明这些基因是主要的宿主特异性决定因素。这是首次报道单噬菌体特异性感染和抑制肠炎沙门氏菌和大肠杆菌 O157:H7。
