Institute for General Microbiology, Christian-Albrechts-Universität zu Kiel, 24118 Kiel, Germany.
Institute of Microbiology, Technische Universität Dresden, 01062 Dresden, Germany.
Viruses. 2021 Sep 26;13(10):1934. doi: 10.3390/v13101934.
Today, the number of known viruses infecting methanogenic archaea is limited. Here, we report on a novel lytic virus, designated Blf4, and its host strain E02.3, a methanogenic archaeon belonging to the Methanomicrobiales, both isolated from a commercial biogas plant in Germany. The virus consists of an icosahedral head 60 nm in diameter and a long non-contractile tail of 125 nm in length, which is consistent with the new isolate belonging to the family. Electron microscopy revealed that Blf4 attaches to the vegetative cells of E02.3 as well as to cellular appendages. Apart from E02.3, none of the tested strains were lysed by Blf4, indicating a narrow host range. The complete 37 kb dsDNA genome of Blf4 contains 63 open reading frames (ORFs), all organized in the same transcriptional direction. For most of the ORFs, potential functions were predicted. In addition, the genome of the host E02.3 was sequenced and assembled, resulting in a 2.6 Mbp draft genome consisting of nine contigs. All genes required for a hydrogenotrophic lifestyle were predicted. A CRISPR/Cas system (type I-U) was identified with six spacers directed against Blf4, indicating that this defense system might not be very efficient in fending off invading Blf4 virus.
目前，已知感染产甲烷古菌的病毒数量有限。在这里，我们报告了一种新型的裂解病毒，命名为 Blf4，及其宿主菌株 E02.3，这是一种产甲烷古菌，属于 Methanomicrobiales，均从德国的一家商业沼气厂中分离得到。该病毒由一个直径为 60nm 的二十面体头部和一个长 125nm 的非收缩长尾组成，与新分离的病毒属于 科一致。电子显微镜显示，Blf4 附着在 E02.3 的营养细胞以及细胞附属物上。除了 E02.3 之外，没有一种测试的 菌株被 Blf4 裂解，表明其宿主范围较窄。Blf4 的完整 37kb dsDNA 基因组包含 63 个开放阅读框（ORFs），全部按照相同的转录方向排列。对于大多数 ORFs，预测了潜在的功能。此外，还对宿主 E02.3 的基因组进行了测序和组装，得到了一个由 9 个 contigs 组成的 2.6 Mbp 草图基因组。预测了所有用于产氢生活方式的基因。鉴定出了一种 CRISPR/Cas 系统（I-U 型），其中有 6 个针对 Blf4 的间隔序列，表明该防御系统在抵御入侵的 Blf4 病毒方面可能不是非常有效。
