Department for Environmental Microbiology, Helmholtz Centre for Environmental Research, Permoserstr. 15, D-04318 Leipzig, Germany.
Department of Environmental Health, Helmholtz Munich, Ingolstaedter Landstr. 1, D-85758 Neuherberg, Germany.
Viruses. 2023 Nov 28;15(12):2330. doi: 10.3390/v15122330.
Huge phages have genomes larger than 200 kilobases, which are particularly interesting for their genetic inventory and evolution. We screened 165 wastewater metagenomes for the presence of viral sequences. After identifying over 600 potential huge phage genomes, we reduced the dataset using manual curation by excluding viral contigs that did not contain viral protein-coding genes or consisted of concatemers of several small phage genomes. This dataset showed seven fully annotated huge phage genomes. The phages grouped into distinct phylogenetic clades, likely forming new genera and families. A phylogenomic analysis between our huge phages and phages with smaller genomes, i.e., less than 200 kb, supported the hypothesis that huge phages have undergone convergent evolution. The genomes contained typical phage protein-coding genes, sequential gene cassettes for metabolic pathways, and complete inventories of tRNA genes covering all standard and rare amino acids. Our study showed a pipeline for huge phage analyses that may lead to new enzymes for therapeutic or biotechnological applications.
巨大噬菌体的基因组大于 200 千碱基，它们的遗传物质和进化过程特别有趣。我们从 165 个废水宏基因组中筛选病毒序列。在鉴定出超过 600 个潜在的巨大噬菌体基因组后，我们通过排除不包含病毒蛋白编码基因或由几个小噬菌体基因组的串联组成的病毒连续体，使用手动编辑来减少数据集。该数据集显示了七个完全注释的巨大噬菌体基因组。噬菌体分为不同的系统发育分支，可能形成新的属和科。我们的巨大噬菌体与基因组较小的噬菌体（即小于 200 kb）之间的系统基因组分析支持了巨大噬菌体经历趋同进化的假设。基因组包含典型的噬菌体蛋白编码基因、代谢途径的连续基因盒以及涵盖所有标准和稀有氨基酸的完整 tRNA 基因库。我们的研究展示了一个巨大噬菌体分析的管道，可能会产生用于治疗或生物技术应用的新酶。
