Lee Heyn, Ku Hye-Jin, Lee Dong-Hoon, Kim You-Tae, Shin Hakdong, Ryu Sangryeol, Lee Ju-Hoon
Department of Food Science and Biotechnology and Institute of Life Science and Resources, Kyung Hee University, Yongin, Republic of Korea.
Department of Food and Animal Biotechnology, Department of Agricultural Biotechnology, Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, Republic of Korea.
PLoS One. 2016 Dec 30;11(12):e0168985. doi: 10.1371/journal.pone.0168985. eCollection 2016.
Escherichia coli O157:H7 and Shigella flexneri are well-known food-borne pathogens causing severe food poisoning at low infectious doses. Bacteriophages have been approved for food applications by the US Food and Drug Administration (FDA) and have been suggested as natural food preservatives to control specific food-borne pathogens. To develop a novel natural food preservative against E. coli O157:H7 and S. flexneri, a new bacteriophage needs to be isolated and characterized.
METHODOLOGY/PRINCIPAL FINDINGS: Bacteriophage HY01 infecting both E. coli O157:H7 and S. flexneri was isolated from a swine fecal sample. HY01 belongs to the family Myoviridae and is stable under various temperature and pH conditions. One-step growth curve analysis showed relatively short eclipse and latent periods as well as large burst size. The 167-kb genome sequence of HY01 was sequenced, and a comparative genome analysis with T4 for non-O157:H7 E. coli suggests that the receptor recognition protein of HY01 plays an important role in determination of host recognition and specificity. In addition, food applications using edible cabbage were conducted with two E. coli O157:H7 strains (ATCC 43890 and ATCC 43895), showing that treatment with HY01 inhibits these clinical and food isolates with >2 log reductions in bacterial load during the first 2 h of incubation.
CONCLUSIONS/SIGNIFICANCE: HY01 can inhibit both E. coli O157:H7 and S. flexneri with large burst size and stability under stress conditions. The ability of HY01 to infect both E. coli O157:H7 and S. flexneri may be derived from the presence of two different host specificity-associated tail genes in the genome. Food applications revealed the specific ability of HY01 to inhibit both pathogens in food, suggesting its potential as a novel biocontrol agent or novel natural food preservative against E. coli O157:H7 and potentially S. flexneri.
大肠杆菌O157:H7和福氏志贺菌是著名的食源性病原体，在低感染剂量下就能引发严重食物中毒。噬菌体已获美国食品药品监督管理局（FDA）批准用于食品领域，并被提议作为天然食品防腐剂来控制特定食源性病原体。为研发一种针对大肠杆菌O157:H7和福氏志贺菌的新型天然食品防腐剂，需要分离并鉴定一种新的噬菌体。
方法/主要发现：从猪粪便样本中分离出了能同时感染大肠杆菌O157:H7和福氏志贺菌的噬菌体HY–01。HY–01属于肌尾噬菌体科，在各种温度和pH条件下都很稳定。一步生长曲线分析显示其隐蔽期和潜伏期相对较短，且裂解量较大。对HY–01的167 kb基因组序列进行了测序，与非O157:H7大肠杆菌的T4噬菌体进行比较基因组分析表明，HY–01的受体识别蛋白在宿主识别和特异性的确定中起重要作用。此外，使用食用卷心菜对两株大肠杆菌O157:H7菌株（ATCC 43890和ATCC 43895）进行了食品应用实验，结果表明，用HY–01处理可在孵育的前2小时内抑制这些临床和食品分离株，使细菌载量降低超过2个对数级。
结论/意义：HY–01能抑制大肠杆菌O157:H7和福氏志贺菌，裂解量较大且在应激条件下稳定。HY–01能够同时感染大肠杆菌O157:H7和福氏志贺菌的能力可能源于基因组中存在两个不同的与宿主特异性相关的尾部基因。食品应用实验揭示了HY–01在食品中抑制这两种病原体的特殊能力，表明其有潜力作为一种新型生物防治剂或新型天然食品防腐剂来对抗大肠杆菌O157:H7以及潜在的福氏志贺菌。
