Department of Food Hygiene and Aquaculture, Faculty of Veterinary Medicine, Ferdowsi University of Mashhadgrid.411301.6, Mashhad, Iran.
German Federal Institute for Risk Assessment, Department Biological Safety, Berlin, Germany.
Appl Environ Microbiol. 2021 Nov 24;87(24):e0142421. doi: 10.1128/AEM.01424-21. Epub 2021 Sep 29.
Phage-based biocontrol of bacteria is considered a natural approach to combat foodborne pathogens. Salmonella spp. are notifiable and highly prevalent pathogens that cause foodborne diseases worldwide. In this study, six bacteriophages were isolated and further characterized that infect food-derived Salmonella isolates from different meat sources. The siphovirus VB_StyS-LmqsSP1, which was isolated from a cow's nasal swab, was further subjected to in-depth characterization. Phage-host interaction investigations in liquid medium showed that vB_StyS-LmqsSP1 can suppress the growth of Salmonella species isolates at 37°C for 10 h and significantly reduce the bacterial titer at 4°C. A reduction of 1.4 to 3 log units was observed in investigations with two food-derived Salmonella isolates and one reference strain under cooling conditions using multiplicities of infection (MOIs) of 10 and 10. Phage application on chicken skin resulted in a reduction of about 2 log units in the tested Salmonella isolates from the first 3 h throughout a 1-week experiment at cooling temperature and with an MOI of 10. The one-step growth curve analysis using vB_StyS-LmqsSP1 demonstrated a 60-min latent period and a burst size of 50 to 61 PFU/infected cell for all tested hosts. Furthermore, the genome of the phage was determined to be free from genes causing undesired effects. Based on the phenotypic and genotypic properties, LmqsSP1 was assigned as a promising candidate for biocontrol of Salmonella enterica serovar Typhimurium in food. Salmonella enterica is one of the major global causes of foodborne enteritis in humans. The use of chemical sanitizers for reducing bacterial pathogens in the food chain can result in the spread of bacterial resistance. Targeted and clean-label intervention strategies can reduce Salmonella contamination in food. The significance of our research demonstrates the suitability of a bacteriophage (vB_StyS-LmqsSP1) for biocontrol of Salmonella enterica serovar Typhimurium on poultry due to its lytic efficacy under conditions prevalent in food production environments.
噬菌体生物防治细菌被认为是一种对抗食源性病原体的自然方法。沙门氏菌是一种具有报告义务的、普遍存在的病原体，可导致全球范围内的食源性疾病。在本研究中，从不同肉类来源的食源性病原体中分离并进一步鉴定了六种感染沙门氏菌的噬菌体。从奶牛鼻腔拭子中分离到的肌尾噬菌体 VB_StyS-LmqsSP1 进一步进行了深入的特性分析。在液体培养基中进行的噬菌体-宿主相互作用研究表明，vB_StyS-LmqsSP1 可以在 37°C 下抑制 10 小时的沙门氏菌属分离株的生长，并在 4°C 时显著降低细菌滴度。在使用感染复数 (MOI) 为 10 和 10 的冷却条件下，对两种食源性病原体分离株和一种参考菌株进行的研究中，观察到细菌滴度降低了 1.4 到 3 个对数单位。在冷却温度下使用 MOI 为 10 的噬菌体对鸡皮进行处理，在 1 周的实验过程中，从第 1 个 3 小时开始，测试的沙门氏菌分离株的数量减少了约 2 个对数单位。使用 vB_StyS-LmqsSP1 进行的一步生长曲线分析表明，所有测试宿主的潜伏期为 60 分钟，感染细胞的爆发量为 50 至 61 PFU/感染细胞。此外，噬菌体的基因组不含引起不良影响的基因。基于表型和基因型特性，LmqsSP1 被鉴定为控制食品中肠炎沙门氏菌的有前途的候选物。肠炎沙门氏菌是人类食源性肠炎的主要全球病因之一。在食物链中使用化学消毒剂来减少细菌病原体可能会导致细菌耐药性的传播。有针对性的和清洁标签的干预策略可以减少食品中的沙门氏菌污染。我们的研究意义在于证明了噬菌体 (vB_StyS-LmqsSP1) 在控制食品生产环境中普遍存在的条件下对肠炎沙门氏菌的噬菌效果，使其适合作为控制肠炎沙门氏菌的生物防治剂。
