How Corrinoids Shape Soil Microbiomes and Ecosystems

Microbiomes in soil are incredibly diverse, with as many as 10,000 species in just a single cup of soil. Researchers are working to better understand how these microbial communities interact with their environment, as their activities can significantly influence the composition and properties of soil.

In two studies published in The ISME Journal, scientists explored how different microbe species exchange vital resources such as vitamins, particularly focusing on corrinoids, a group of nutrients that includes vitamin B12. Many bacteria in the environment cannot produce these essential nutrients on their own.

By focusing on a single nutrient, the researchers were able to study microbiomes in more detail. Both studies focused on the same California grassland soil, providing a framework for understanding nutrient cycling within the ecosystem.

The first study examined how corrinoids impacted individual bacteria. The team isolated more than 100 bacteria, including 37 new species, to test if they could produce corrinoids or if they would need to rely on others to supply these nutrients. They found that 60% of the bacteria produced corrinoids, but only a few released them into the environment, suggesting that corrinoid-producing organisms could provide essential nutrients to other members of the microbiome, influencing its assembly and function.

The second study analyzed the levels of corrinoids in the soil itself. The results showed that soil contains corrinoids in excess of what is needed for microbial growth, although most of these nutrients are bound to soil particles. Adding different types of corrinoids to the soil temporarily altered the microbiome, suggesting that these nutrients could be used to manipulate the structure and behavior of microbial communities in both natural and engineered systems.

Soils play a crucial role in maintaining ecosystem health by storing organic matter, cycling nutrients, filtering water, and supporting plant growth. Since microbes are integral to these soil processes, understanding how to influence their behavior could improve soil quality and function.

The two studies demonstrated that the presence of corrinoids can impact how individual soil bacteria grow in the lab and how they coexist in the environment. This research opens up new possibilities for manipulating microbiomes to improve soil health and optimize the benefits that soils provide to ecosystems.