肠杆菌噬菌体 vB_EclM_HK6 的特性及其基因组分析，有望成为控制污染食品的阴沟肠杆菌传播的生物防治方法。

BACKGROUND: Increased prevalence of Enterobacter cloacae within food products underscores food as an underexplored reservoir for antibiotic resistance, thus requiring particular intervention. Bacteriophages have been explored as a promising approach for controlling bacterial growth in different matrices. Moreover, their specific interaction and self-replication, put them apart from traditional methods for controlling bacteria in different matrices. METHODS: Sixteen Enterobacter cloacae strains were recovered from raw chicken. These strains were used to isolate bacteriophages using enrichment protocol. The broad-spectrum bacteriophage was evaluated in terms of thermal, pH, shearing stress and storge. Moreover, its infection kinetics, in vitro antibacterial activity, cytotoxicity were also assessed. Genomic sequencing was performed to exclude any potential virulence or resistance genes. Finally, the capability of the isolated phages to control bacterial growth in different chicken samples was assessed alone and in combination with sodium nitrite. RESULTS: The lytic bacteriophage vB_EclM_HK6 was isolated and showed the broadest spectrum being able to infect 8/16 E. cloacae strains with a lytic activity against its host strain, E. cloacae EC21, as low as MOI of 10. The phage displays a latent period of 10 min and burst size of 115 ± 44 and resistance frequency of 5.7 × 10 ± 3.0 × 10. Stability assessment revealed a thermal tolerance up to 60 ˚C, wide range pH stability (3-10) and the ability to withstand shearing stress up to 250 rpm. HK6 shows no cytotoxicity against oral epithelial cells up to 10 PFU/ml. Genomic analysis revealed a Strabovirus with total size of 177,845 bp that is free from known resistance and virulence genes. Finally, HK6 pretreatment of raw chicken, chicken nuggets and ready-made cheese salad shows a reduced bacterial count up to 4.6, 2.96 and 2.81 log-units, respectively. Moreover, combing HK6 with sodium nitrite further improved the antibacterial activity in both raw chicken and chicken nuggets without significant enhancement in case of cheese salad. CONCLUSION: Enterobacter bacteriophage vB_EclM_HK6 presents a safe and effective approach for controlling E. cloacae contaminating stored chicken food samples. Moreover, they could be combined with a reduced concentrations of sodium nitrite to improve the killing capacity.

背景：食品中阴沟肠杆菌的流行率增加，突显了食品是抗生素耐药性研究不足的一个潜在来源，因此需要特别干预。噬菌体已被探索作为控制不同基质中细菌生长的一种很有前途的方法。此外，它们的特异性相互作用和自我复制使它们有别于控制不同基质中细菌的传统方法。

方法：从生鸡肉中回收了 16 株阴沟肠杆菌。使用富集方案从这些菌株中分离噬菌体。从热、pH 值、剪切应力和储存等方面评估广谱噬菌体。此外，还评估了其感染动力学、体外抗菌活性和细胞毒性。进行基因组测序以排除任何潜在的毒力或耐药基因。最后，评估了分离的噬菌体单独和与亚硝酸钠联合控制不同鸡肉样本中细菌生长的能力。

结果：分离出裂解噬菌体 vB_EclM_HK6，显示出最广泛的谱，可以感染 16 株阴沟肠杆菌中的 8 株，对其宿主菌株阴沟肠杆菌 EC21 的裂解活性低至 MOI 为 10。噬菌体的潜伏期为 10 分钟，爆发量为 115±44，耐药频率为 5.7×10±3.0×10。稳定性评估显示，其热耐受性高达 60℃，pH 值范围宽（3-10），可承受高达 250rpm 的剪切应力。HK6 对口腔上皮细胞的细胞毒性在 10 PFU/ml 以下。基因组分析显示，该噬菌体属于 Strabovirus，全长 177845bp，不含已知的耐药和毒力基因。最后，HK6 预处理生鸡肉、鸡块和即食奶酪沙拉可使细菌计数分别减少 4.6、2.96 和 2.81 个对数单位。此外，在生鸡肉和鸡块中结合 HK6 和亚硝酸钠进一步提高了抗菌活性，而在奶酪沙拉中没有显著增强。

结论：阴沟肠杆菌噬菌体 vB_EclM_HK6 为控制污染储存鸡肉食品样本中的阴沟肠杆菌提供了一种安全有效的方法。此外，它们可以与较低浓度的亚硝酸钠结合使用，以提高杀菌能力。