Abundance measurements reveal the balance between lysis and lysogeny in the human gut microbiome.
Level 5 - mechanism / opinion, no new human data
Level 5 by design analogy; ecological modeling combined with reanalyzed human datasets and gnotobiotic mouse experiments (bench/animal research).
PubMed 40300605 · doi:10.1016/j.cub.2025.03.073
What was done
The authors combined imaging and sequencing data from prior human studies with a generalized mathematical model of temperate phage dynamics to quantify gut phage population dynamics and lifestyle traits. They validated model predictions using a synthetic microbial community in gnotobiotic mice.
What was found
The average human gut was found to have a low ratio of phage particles to bacterial cells (~1:100) but a higher ratio of phage genomes to bacterial genomes (~4:1), indicating that most gut phages are temperate (e.g., integrated prophages or phage-plasmids). Phage induction and bacterial lysis occur at low baseline rates (~0.001-0.01 per bacterium per day), imposing modest fitness costs. In gnotobiotic mice, phage composition could be quantitatively predicted purely from bacterial abundances.
Why it matters
This clarifies that temperate lysogeny dominates over active lytic predation in the healthy human gut. The resulting quantitative model establishes a foundation for interpreting how phage-bacterial dynamics influence microbiome stability and human health.
Limits
The abstract reports no human sample size, demographic data, or specific clinical cohorts for the underlying datasets. Experimental validation relied on a synthetic community in gnotobiotic mice, which may not capture full human microbiome complexity, diet variations, or environmental stressors.
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