College of Food Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
Key Laboratory of Environment Correlative Dietology, Huazhong Agricultural University, Wuhan 430070, China; College of Food Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
Food Res Int. 2021 Feb;140:110004. doi: 10.1016/j.foodres.2020.110004. Epub 2020 Dec 24.
Salmonella is one of the most common causes of foodborne diseases and can cause severe economic loss. Increased antibiotic resistance, particularly of multidrug-resistant strains, has led to the use of phages as substitute agents. However, bacteriophages are usually sensitive to harsh environments. At present, microencapsulation is one of the methods to solve this problem. But there are few studies on the application of microencapsulated bacteriophages in food matrix. In this study, a novel Salmonella phage T156 was firstly studied for its biological characteristics. T156 belongs to the T5-like Siphoviridae family, with broad host spectrum and potent lytic ability against tested Salmonella strains, including multiple antibiotic-resistant Salmonella. It also showed valuable characteristics such as high pH (3.0-12.0), thermal tolerances (30-50 °C) and a short latent period (10 min). Genome analysis indicated T156 genome comprised a 123,849 bp DNA with 176 putative open reading frames, of which 56 ORFs were annotated to known functions. No genes associated with antibiotic resistance, virulence factor and lysogeny were found in T156 genome. Then, orifice-coagulation bath method was used to microencapsulate bacteriophage T156. Microencapsulated bacteriophage can effectively inhibit the growth of Salmonella in artificially contaminated milk and lettuce at 4 °C and 25 °C. At 25 °C, the maximum antibacterial efficacy of phage in milk and lettuce were 57.93% and 55.47%, respectively. This is the first report about microencapsulated bacteriophage infecting Salmonella in food matrix. It can provide insights into fundamental researches on microencapsulated bacteriophage for future utilization in food.
沙门氏菌是食源性疾病最常见的原因之一，可造成严重的经济损失。抗生素耐药性的增加，特别是多药耐药菌株的增加，导致噬菌体被用作替代药物。然而，噬菌体通常对恶劣环境敏感。目前，微胶囊化是解决这个问题的方法之一。但是，关于微囊化噬菌体在食品基质中的应用的研究很少。在本研究中，首先研究了一种新型的沙门氏菌噬菌体 T156 的生物学特性。T156 属于 T5 样的长尾噬菌体科，对测试的沙门氏菌菌株具有广泛的宿主谱和强大的裂解能力，包括多重抗生素耐药的沙门氏菌。它还具有高 pH 值（3.0-12.0）、热耐受性（30-50°C）和潜伏期短（10 分钟）等有价值的特性。基因组分析表明，T156 基因组由 123849bp 的 DNA 组成，包含 176 个可能的开放阅读框，其中 56 个 ORF 被注释为已知功能。在 T156 基因组中未发现与抗生素耐药性、毒力因子和溶原性相关的基因。然后，采用孔凝固浴法对噬菌体 T156 进行微囊化。微囊化噬菌体可有效抑制人工污染牛奶和生菜中沙门氏菌的生长，在 4°C 和 25°C 下。在 25°C 下，噬菌体在牛奶和生菜中的最大抑菌效果分别为 57.93%和 55.47%。这是关于微囊化噬菌体在食品基质中感染沙门氏菌的首次报道。它可以为未来在食品中利用微囊化噬菌体提供基础研究的见解。
