School of Food Science and Technology, Yangzhou University, Yangzhou, Jiangsu, 225127, PR China.
School of Food Science and Technology, Yangzhou University, Yangzhou, Jiangsu, 225127, PR China.
Microb Pathog. 2023 Jun;179:106098. doi: 10.1016/j.micpath.2023.106098. Epub 2023 Apr 6.
Citrobacter freundii is an important foodborne pathogen that can cause urethritis, bacteremia, necrotizing abscess, and meningitis in infants. In this study, a gas-producing isolate from vacuum-packed meat products was identified as C. freundii by 16S rDNA. In addition, a new virulent phage YZU-L1, which could specifically lyse C. freundii, was isolated from sewage samples in Yangzhou. Transmission electron microscopy showed that phage YZU-L1 had a polyhedral head of 73.51 nm in diameter and a long tail of 161.15 nm in length. According to phylogenetic analysis employing the terminase large subunit, phage YZU-L1 belonged to the Demerecviridae family and the Markadamsvirinae subfamily. The burst size was 96 PFU/cell after 30 min of latent period and 90 min of rising period. Phage YZU-L1 could maintain high activity at pH of 4-13, and resist 50 °C for up to 60 min. The complete genome of YZU-L1 was 115,014 bp double-stranded DNA with 39.94% G + C content, encoding 164 open reading frames (ORFs), without genes encoding for virulence, antibiotic resistance, or lysogenicity. Phage YZU-L1 treatment significantly reduced the viable bacterial count of C. freundii in a sterile fish juice model, which is expected to be a natural agent for the biocontrol of C. freundii in foods.
弗氏柠檬酸杆菌是一种重要的食源性致病菌，可引起婴儿尿道炎、菌血症、坏死性脓肿和脑膜炎。本研究从真空包装肉制品中分离到一株产气菌株，通过 16S rDNA 鉴定为弗氏柠檬酸杆菌。此外，从扬州污水样中分离到一株可特异性裂解弗氏柠檬酸杆菌的新烈性噬菌体 YZU-L1。透射电镜观察显示，噬菌体 YZU-L1 头部为多面体，直径为 73.51nm，尾部为长杆状，长 161.15nm。根据末端酶大亚基的系统发育分析，噬菌体 YZU-L1 属于德美病毒科、马当病毒亚科。潜伏期 30min，上升期 90min，裂解量为 96PFU/细胞。噬菌体 YZU-L1 在 pH 值为 4-13 时能保持较高的活性，50°C 处理 60min 仍具有较高的活性。YZU-L1 的基因组全长为 115014bp 的双链 DNA，G+C 含量为 39.94%，编码 164 个开放阅读框（ORFs），不含有毒力、抗生素耐药性或溶原性相关基因。噬菌体 YZU-L1 处理可显著降低无菌鱼汁模型中弗氏柠檬酸杆菌的活菌数，有望成为食品中弗氏柠檬酸杆菌生物防治的天然制剂。
