Phages Unlock Vitamin B12 for Microbial Communities

Researchers from Virginia Tech have uncovered a novel mechanism by which bacteriophages, viruses that infect bacteria, can release vitamin B12 trapped inside bacterial cells. This process allows neighboring microbes, which cannot produce B12 themselves, to access this essential nutrient, reshaping microbial communities.

Vitamin B12, also known as cobalamin, is crucial for DNA synthesis, red blood cell formation, and nerve function. However, it is produced only by certain bacteria and archaea. The study, published in The ISME Journal, reveals that phage-driven bacterial rupture releases B12, which can then be utilized by other microbes.

The researchers demonstrated this by using a controlled system with a B12-producing bacterium and another bacterium that required B12 but could not produce it. When a phage infected and destroyed the B12-producing cells, the vitamin was released into the environment, supporting the growth of the dependent bacteria.

Further experiments showed that the presence of B12 was essential for microbial growth. When phages lysed B12-producing bacteria, the diversity of bacterial communities increased, indicating that phages play a role in nutrient recycling by releasing valuable molecules like B12.

This discovery highlights the ecological role of phages beyond merely killing bacteria. By releasing nutrients, phages can influence microbial ecosystems in various environments, including the human gut, soil, and oceans.