Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Quebec City, QC, G1V 0A6, Canada.
Département de biochimie, de microbiologie et de bio-informatique, Faculté des sciences et de génie, Université Laval, Quebec City, QC, G1V 0A6, Canada.
Sci Rep. 2017 Aug 1;7(1):7054. doi: 10.1038/s41598-017-07401-7.
Phages infecting Aeromonas salmonicida subsp. salmonicida, the causative agent of the fish disease furunculosis, have been isolated for decades but very few of them have been characterized. Here, the host range of 12 virulent phages, including three isolated in the present study, was evaluated against a panel of 65 A. salmonicida isolates, including representatives of the psychrophilic subspecies salmonicida, smithia, masoucida, and the mesophilic subspecies pectinolytica. This bacterial set also included three isolates from India suspected of being members of a new subspecies. Our results allowed to elucidate a lytic dichotomy based on the lifestyle of A. salmonicida (mesophilic or psychrophilic) and more generally, on phage types (lysotypes) for the subspecies salmonicida. The genomic analyses of the 12 phages from this study with those available in GenBank led us to propose an A. salmonicida phage pan-virome. Our comparative genomic analyses also suggest that some phage genes were under positive selection and A. salmonicida phage genomes having a discrepancy in GC% compared to the host genome encode tRNA genes to likely overpass the bias in codon usage. Finally, we propose a new classification scheme for A. salmonicida phages.
已分离出感染鱼类疖病病原体——嗜水气单胞菌亚种鲑鱼的噬菌体数十年,但对它们的了解却非常有限。本研究中,评估了 12 种烈性噬菌体(包括三种本研究中分离出的噬菌体)的宿主范围,针对的是包括嗜冷亚种鲑鱼、史密斯亚种、麻萨亚种和中温亚种果胶酶亚种的 65 种嗜水气单胞菌分离株的一个小组。该细菌集还包括来自印度的三个被怀疑是新亚种成员的分离株。我们的研究结果阐明了一种基于嗜水气单胞菌生活方式(中温或嗜冷)和更普遍的基于噬菌体类型(溶菌型)的裂解二分法,适用于鲑鱼亚种。对本研究中 12 种噬菌体的基因组分析以及 GenBank 中现有的基因组分析使我们提出了一个嗜水气单胞菌噬菌体泛病毒组。我们的比较基因组分析还表明,一些噬菌体基因受到正选择的影响,与宿主基因组相比,GC% 存在差异的嗜水气单胞菌噬菌体基因组编码 tRNA 基因,以可能克服密码子使用偏好的偏差。最后,我们提出了一种新的嗜水气单胞菌噬菌体分类方案。