Energetic constraints on the viruses of anaerobes: molecular adaptations and ecological consequences

Phage proliferation depends on factors like environmental conditions, metabolic resources, and host-provided energy. Gibbs free energy can be limited in anoxic habitats, yet bacteriophages survive and thrive. Despite many natural environments being anoxic, phages of anaerobes remain understudied compared to phages of aerobes. Phages are successful both in aerobic biomes with dense bacterial communities and in anaerobic biomes where microbial hosts are sparse and have low turnover. Our overarching goal is to elucidate how phages adapt to these energy-limited conditions. We co-enriched bacteria and their viruses anoxically from river water using nitrate and sulfate as electron acceptors. Full-length 16S rRNA and viromes were sequenced to analyze bacterial and viral community responses to contrasting energy regimes. During enrichment, the microbiome and virome shifted towards distinct substrate-specific bacterial and viral communities. Host predictions linked enriched phages to bacterial taxa consistent with 16S community profiles. We are currently investigating virome community adaptations in regulatory, structural, and auxiliary metabolic genes. Ongoing work focuses on isolating representative bacteria and their phages from the enriched communities for further structural and functional characterization, ultimately to study the adaptations that allow these phages to survive at low-energy conditions. Enrichment experiments under additional low-energy electron acceptors are currently ongoing. These findings contribute to the JSMC theme of Microbial Communication by revealing how energy availability shapes phage-host interactions and drives community-level adaptations in anoxic environments.

PhD start: 03/20/2024