Phage-induced lysis of a B12-producing bacterium releases vitamin B12 in sufficient amounts to support neighboring B12-dependent microbes, whereas intact producer cells do not release usable B12.

Control experiments with a B12 non-producer mutant confirm that B12 release is necessary for the growth of dependent microbes, not merely a consequence of cell rupture.

Viruses that infect bacteria can trigger lysis and spill cellular contents, including vitamin B12, into the surrounding environment.

The work broadens the ecological role of viruses in microbiomes, suggesting phage activity can influence nutrient access and community dynamics in the gut, soil, and oceans.

Reference: Barreira et al., ISME Journal, 2026, ‘Bacteriophage-mediated cell lysis externalizes a metabolically valuable nutrient to broadly modulate bacterial communities.’

The findings propose phages function as nutrient recyclers, moving valuable metabolites from producers to consumers and shaping microbial ecosystems beyond predator-prey dynamics.

In complex gut communities, phage-triggered B12 release altered community composition and increased diversity, with effects linked to the timing and localization of nutrient release rather than B12 addition alone.

Vitamin B12 is a metabolically expensive nutrient produced by only certain bacteria and archaea, making many organisms reliant on external sources or cobamides.