Soleimani-Delfan Abbas, Bouzari Majid, Wang Ran
Department of Cell and Molecular Biology & Microbiology, Faculty of Biological Science and Technology, University of Isfahan, Hezar-Jereeb Street, 81746-73441, Isfahan, Iran.
State Key Laboratory Cultivation Base of MOST, Institute of Food Safety and Nutrition, Jiangsu Academy of Agricultural Sciences, Nanjing, PR China.
Virus Res. 2021 Jun;298:198391. doi: 10.1016/j.virusres.2021.198391. Epub 2021 Mar 15.
Enterococcus faecalis is an environmental agent of bovine mastitis in cows and has many cytopathic effects on the urinary tract in both humans and animals. In this study, a novel lytic bacteriophage, vB_EfaS-DELF1, was isolated against 21 E. faecalis isolated from bovine mastitis, including vancomycin-resistant E. faecalis (VRE). vB_EfaS-DELF1 bacteriophage was specific for E. faecalis and showed no lytic effects against other tested Enterococcus spp., Gram-negative, or Gram-positive bacteria. Moreover, no activity was observed against yogurt starters. The phage suspension was stable in a wide range of pH, salinity, and temperature. It retained its activity in 3.5 % fat milk. vB_EfaS-DELF1 has the common phenotypic features of Siphoviridae with a double-strand DNA of 40,248 bp in length and a G + C content of 34.9 %. The genome encodes 62 putative ORFs and no tRNA. No undesirable genes such as lysogenic mediators, antibiotic resistance, or virulence factor genes were detected in the genome. The comparative genomic analysis demonstrated similarity to the other available phage genomes. The highest similarity was observed with two other phages (50 % coverage and 82.38 % identities with IME-EFm1; 35 % coverage and 86.22 % identities with IME-EFm5) that were placed in the same clade. The differences with the other aligned phages were high and were placed in distant clusters. Regarding the specificity of this new bacteriophage against all of the tested E. faecalis isolates and, in particular, against the vancomycin-resistant ones, and also the absence of antibiotic resistance or virulence genes in its genome, vB_EfaS-DELF1 is suggested as a potential candidate for biocontrol of E. faecalis infections.
粪肠球菌是奶牛乳房炎的一种环境致病因子，对人和动物的泌尿道均有多种细胞病变作用。在本研究中，针对从奶牛乳房炎中分离出的21株粪肠球菌，包括耐万古霉素粪肠球菌（VRE），分离出一种新型裂解性噬菌体vB_EfaS - DELF1。vB_EfaS - DELF1噬菌体对粪肠球菌具有特异性，对其他测试的肠球菌属、革兰氏阴性菌或革兰氏阳性菌均无裂解作用。此外，对酸奶发酵剂也无活性。噬菌体悬液在广泛的pH值、盐度和温度范围内稳定。它在3.5%脂肪乳中仍保持活性。vB_EfaS - DELF1具有长尾噬菌体科的常见表型特征，双链DNA长度为40248 bp，G + C含量为34.9%。基因组编码62个推定的开放阅读框，无转运RNA。基因组中未检测到诸如溶原介导因子、抗生素抗性或毒力因子基因等不良基因。比较基因组分析表明其与其他可用噬菌体基因组具有相似性。与另外两个位于同一进化枝的噬菌体相似度最高（与IME - EFm1的覆盖度为50%，同一性为82.38%；与IME - EFm5的覆盖度为35%，同一性为86.22%）。与其他比对噬菌体的差异较大，位于较远的簇中。鉴于这种新型噬菌体对所有测试的粪肠球菌分离株，特别是对耐万古霉素分离株具有特异性，且其基因组中不存在抗生素抗性或毒力基因，vB_EfaS - DELF1被认为是粪肠球菌感染生物防治的潜在候选者。
