College of Food Science and Engineering, Yangzhou University, Yangzhou, Jiangsu 225001, People's Republic of China.
Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, Jiangsu 225001, People's Republic of China.
J Food Prot. 2021 Sep 1;84(9):1629-1639. doi: 10.4315/JFP-20-460.
Ready-to-eat vegetable salads have gained popularity worldwide. However, the microbial safety of these salads is a health concern, primarily due to Salmonella Enteritidis contamination during the growing, harvesting, processing, and handling of produce. In this study, a bacteriophage-based strategy was developed to control Salmonella Enteritidis growth in mixed-ingredient salads. The lytic Salmonella-specific phage SapYZU01 was isolated from a soil sample from a suburban vegetable field in Yangzhou (People's Republic of China). SapYZU01 has a short latent period, a large burst size, and a lytic effect against 13 Salmonella Enteritidis strains isolated from various sources (human samples, pork, deli foods, chickens, and chicken meat). The SapYZU01 genome did not contain virulence or antibiotic resistance genes. SapYZU01 significantly decreased the viability of Salmonella Enteritidis cells in iceberg lettuce, chicken meat, and mixed-ingredient (lettuce plus chicken) salads at 37 and 25°C. Bacterial levels in the salad decreased significantly (by 4.0 log CFU/g) at 25°C after treatment of contaminated lettuce before salad preparation with SapYZU01 at a multiplicity of infection (MOI) of 100. Bacterial levels were decreased by 3.8 log CFU/g at 25°C in lettuce plus chicken salads treated after the salad preparation with SapYZU01 at an MOI of 100. In contrast, treating cooked chicken meat with SapYZU01 at an MOI of 100 before mixing it with contaminated lettuce decreased the bacterial level of the salad by 1.2 log CFU/g at 25°C. These findings indicate the potential application of SapYZU01 as a natural biocontrol agent against Salmonella Enteritidis in mixed-ingredient salads. However, both the treatment method and the bacteriophage MOI must be considered when using this lytic bacteriophage in mixed-ingredient salads.
即食蔬菜沙拉在全球范围内广受欢迎。然而，这些沙拉的微生物安全性是一个健康关注点，主要是由于在农产品的种植、收获、加工和处理过程中受到肠炎沙门氏菌的污染。在本研究中，开发了一种基于噬菌体的策略来控制混合成分沙拉中的肠炎沙门氏菌生长。从扬州市（中华人民共和国）郊区蔬菜田的土壤样本中分离出了裂解性肠炎沙门氏菌特异性噬菌体 SapYZU01。SapYZU01 潜伏期短、爆发量大，对来自不同来源（人类样本、猪肉、熟食、鸡和鸡肉）的 13 株肠炎沙门氏菌均具有裂解作用。SapYZU01 基因组不含有毒力或抗生素耐药基因。SapYZU01 在 37 和 25°C 时显著降低了冰生菜、鸡肉和混合成分（生菜加鸡肉）沙拉中肠炎沙门氏菌细胞的活力。在制备沙拉前用 SapYZU01（感染复数 MOI 为 100）处理污染生菜，可使 25°C 时沙拉中细菌水平显著下降（降低 4.0 log CFU/g）。在制备沙拉后用 SapYZU01（MOI 为 100）处理生菜加鸡肉沙拉，可使 25°C 时沙拉中细菌水平降低 3.8 log CFU/g。相比之下，在将污染的生菜与 SapYZU01（MOI 为 100）处理过的熟鸡肉混合前用 SapYZU01 处理鸡肉，可使 25°C 时沙拉中的细菌水平降低 1.2 log CFU/g。这些发现表明，SapYZU01 有作为一种天然生物防治剂在混合成分沙拉中控制肠炎沙门氏菌的应用潜力。然而，在混合成分沙拉中使用这种裂解性噬菌体时，必须考虑处理方法和噬菌体 MOI。
