Ren Qinghai, Wang Zhiwei, Ge Yichen, Huang Yucui, Zhang Wei, Liu Chunxue, Li Yubao, Cao Shengliang
College of Agriculture and Biology, Liaocheng University, Liaocheng, Shandong, China.
College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.
Front Microbiol. 2025 Feb 6;16:1516223. doi: 10.3389/fmicb.2025.1516223. eCollection 2025.
Foodborne bacteria, particularly () O157:H7, are significant contributors to foodborne illnesses, with antibiotic overuse exacerbating the issue through the emergence of multidrug-resistant strains. This study investigated the potential of phages in food safety, examining their biological traits and bacteriostatic properties. Two phages (vB_EcoP_SD2, vB_EcoP_SD6) of O157:H7 were isolated from slaughterhouse sewage and characterized for morphology, genomic composition, phage phylogenetic tree, optimal multiplicity of infection (MOI), one-step growth curve, thermal and pH stability and antibacterial efficacy. The optimal MOIs of vB_EcoP_SD2 and vB_EcoP_SD6 was 0.1 and 0.01, and temperature range for maintaining activity was 4°C to 55°C. The host range of vB_EcoP_SD2 and vB_EcoP_SD6 was 65% (13/20) and 55% (11/20), which was partially complementary to each other (75%, 15/20). Notably, vB_EcoP_SD2 displayed a latent period of 10 min, a burst period of 80 min, and a burst volume of 80 PFU per cell, while vB_EcoP_SD6 had a burst volume of 10 PFU per cell. Comprehensive whole-genome analysis confirmed two phages has no presence of pathogenic factors or resistance genes. Genomic comparisons suggest vB_EcoP_SD2 and vB_EcoP_SD6, respectively, constituted a novel member of a new genus, Justusliebigvirus genus and Kayfunavirus genus which genome, respectively, was found to be 1,49,066 bp, 40,202 bp long with an average GC content of 37.5 and 49.8%. The phages effectively inhibited host bacteria in LB broth for at least 6 h and showed promise in inhibiting bacteria in milk and pork, which indicated that the two phages exhibited a favorable bacteriostatic effect on milk and pork within the first 6 h under the optimal MOI. In the milk bacteriostasis experiment, vB_EcoP_SD2 could reduce bacteria by 3.16 × 10 CFU/mL, and vB_EcoP_SD6 could reduce bacteria by 1.05 × 10 CFU/mL. Phage vB_EcoP_SD2 decreased bacteria by 1.14 × 10 CFU/mL, and vB_EcoP_SD6 decreased bacteria by 2.04 × 10 CFU/mL in the pork. There was no disparity in bacteriostatic effect of different MOI within the first 6 h, but bacteriostatic effect of all groups still remained different from that of the control group. This study indicates the two phages possess excellent biological characteristics, thereby providing a theoretical foundation for the subsequent development of natural fungicides.
食源细菌，尤其是肠出血性大肠杆菌O157:H7，是食源性疾病的重要致病因素，抗生素的过度使用通过产生多重耐药菌株使这一问题更加严重。本研究调查了噬菌体在食品安全方面的潜力，研究了它们的生物学特性和抑菌特性。从屠宰场污水中分离出两株O157:H7噬菌体（vB_EcoP_SD2、vB_EcoP_SD6），并对其形态、基因组组成、噬菌体系统发育树、最佳感染复数（MOI）、一步生长曲线、热稳定性和pH稳定性以及抗菌效果进行了表征。vB_EcoP_SD2和vB_EcoP_SD6的最佳MOI分别为0.1和0.01，保持活性的温度范围为4℃至55℃。vB_EcoP_SD2和vB_EcoP_SD6的宿主范围分别为65%（13/20）和55%（11/20），二者部分互补（75%，15/20）。值得注意的是，vB_EcoP_SD2的潜伏期为10分钟，爆发期为80分钟，每个细胞的爆发量为80个噬菌斑形成单位（PFU），而vB_EcoP_SD6每个细胞的爆发量为10个PFU。全面的全基因组分析证实这两种噬菌体不存在致病因子或耐药基因。基因组比较表明，vB_EcoP_SD2和vB_EcoP_SD6分别构成了一个新属的新成员，即Justusliebigvirus属和Kayfunavirus属，其基因组长度分别为149,066 bp和40,202 bp，平均GC含量分别为37.5%和49.8%。这些噬菌体在LB肉汤中能有效抑制宿主细菌至少6小时，并且在抑制牛奶和猪肉中的细菌方面表现出前景，这表明在最佳MOI下，这两种噬菌体在最初6小时内对牛奶和猪肉具有良好的抑菌效果。在牛奶抑菌实验中，vB_EcoP_SD2可使细菌减少3.16×10 CFU/mL，vB_EcoP_SD6可使细菌减少1.05×10 CFU/mL。在猪肉中，噬菌体vB_EcoP_SD2使细菌减少1.14×10 CFU/mL，vB_EcoP_SD6使细菌减少2.04×10 CFU/mL。在最初6小时内，不同MOI的抑菌效果没有差异，但所有组的抑菌效果仍与对照组不同。本研究表明这两种噬菌体具有优异的生物学特性，从而为后续开发天然杀菌剂提供了理论基础。
