Two viruses, MCV1 and MCV2, which infect Marinitoga bacteria isolated from deep‐sea hydrothermal vents: functional and genomic analysis

Abstract

Viruses represent a driving force in the evolution of microorganisms including those thriving in extreme environments. However, our knowledge of the viral diversity associated to microorganisms inhabiting the deep-sea hydrothermal vents remains limited. The phylum of Thermotogae, including thermophilic bacteria, is well represented in this environment. Only one virus was described in this phylum, MPV1 carried by Marinitoga piezophila. In this study, we report on the functional and genomic characterization of two new bacterioviruses that infect bacteria from the Marinitoga genus. Marinitoga camini virus 1 and 2 (MCV1 and MCV2) are temperate siphoviruses with a linear dsDNA genome of 53.4 kb and 50.5 kb respectively. Here, we present a comparative genomic analysis of the MCV1 and MCV2 viral genomes with that of MPV1. The results indicate that even if the host strains come from geographically distant sites, their genomes share numerous similarities. Interestingly, heavy metals did not induce viral production, instead the host of MCV1 produced membrane vesicles. This study highlights interaction of mobile genetic elements (MGE) with their hosts and the importance of including hosts-MGEs' relationships in ecological studies.

Newly identified proviruses in Thermotogota suggest that viruses are the vehicles on the highways of interphylum gene sharing

“…Based on tail morphology, TAV1 was classified to the order Caudovirales and the family Siphoviridae, confirming the classification using bioinformatic tools. This is similar to the three previously characterized temperate Marinitoga viruses, whose virion tails were just slightly longer [15,16]. TAV1 induction produced low amounts of virions upon mitomycin C induction (data not shown).…”

Thermosipho spp. immune system differences affect variation in genome size and geographical distributions

“…Recent reports have identified three temperate siphoviruses in Thermotogae genomes, and together with the above findings, it becomes clear that prophages are not unusual genomic features within this phylum ( Lossouarn et al. 2015 ; Mercier et al. 2018 ).…”

Thermosiphospp. immune system differences affect variation in genome size and geographical distributions

“…Interestingly, several of these regions encode likely integrated prophages ( T. melanesiensis BI429 / BI431, T. affectus BI1074, T. africanus H17ap60334) as they contain typical phage genes (Supplementary information, Supplementary materials Table S4). Recent reports have identified three temperate siphoviruses in Thermotogae genomes, and together with the above findings, it becomes clear that prophages are not unusual genomic features within this phylum (Lossouarn et al 2015; Mercier et al 2018). The remaining clusters are dominated by hypothetical proteins, CRISPR-cas genes or genes involved in various types of cellular activities (Supplementary materials Table S4).…”