Les dynamiques hôte-virus dans les digesteurs anaérobies sous l'effet d'un stress abiotique

Le résumé fourni par la source

Viruses of microbes are major players in various ecosystems, influencing the structure and dynamics of microbial communities. Despite this, their presence and impact in anaerobic digestion (AD) processes remain underexplored. AD ecosystems are highly sensitive to disturbances, which can lead to inhibition and reduced methane production. In this PhD work, I investigated the interplay between abiotic disturbance, microbial community composition - including viromes - and AD process performance. I monitored viral population dynamics in anaerobic digesters using metavirome shotgun sequencing. One objective was to determine whether abiotic stresses known to inhibit AD can trigger the production of temperate viruses through provirus induction. Another aim was to identify novel virus-host pairs by employing bioinformatics approaches. The results revealed high diversity among both prokaryotes and viruses, with Clostridiales dominating the prokaryotic community and Caudoviricetes prevailing in the microbial viruses. Numerous viruses and hosts showed differential abundance under disturbing conditions, with a strong concordance between host and virus dynamics. Contrary to expectations, abiotic stresses did not significantly induce prophages, suggesting that viruses may exert a more gradual influence over time rather than causing abrupt “time bomb” effects. Additionally, this study expands the knowledge on AD, highlighting the significant diversity and novelty of AD viruses. I identified new virus-host pairs and annotated manually the genome of a novel spindle-shaped virus, along with other viral genomes. This may lead to the creation of a new family of viruses infecting methanogenic archaea.

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