Manipulating microbial communities with vitamins

Despite the critical roles these communities play in the health of our environment, their size and complexity make it difficult to understand how each microbe contributes to ecosystem-level processes. To address this challenge, researchers in the lab of Michi Taga, a professor in the Department of Plant and Microbial Biology, developed a model that allows them to dissect how one nutrient impacts microbial communities across scales—from the individual microbe to the ecosystem level—by influencing intermicrobial interactions. 

This approach was named the “corrinoid model” by Taga because it focuses on the corrinoid family of nutrients related to vitamin B12. She served as the corresponding author for two papers in The International Society for Microbial Ecology (ISME) Journal that outlined the lab’s research and applications of the corrinoid model to understand microbial interactions in a California grassland soil.

In one study led by Zoila Alvarez-Aponte, a PhD candidate in the Taga lab, researchers isolated bacteria from the soil and studied them in the laboratory, culturing more than 100 different bacterial species including 37 that they discovered for the first time. The authors characterized each species, testing whether the bacteria can produce corrinoids for themselves or depend on neighboring microbes to provide them. “We found that surprisingly, all the isolates either synthesize or prefer B12, in contrast to the dozen other corrinoids that have been discovered in many other environments,” said Alvarez-Aponte.

A second study focused on how corrinoids impact the soil environment. “Despite previous results suggesting that corrinoids are limiting nutrients in soil, our chemical prospecting demonstrates that there is actually a deep reservoir of vitamin B12 present in soils,” said postdoctoral researcher Zachary Hallberg, who co-led the study with Alexa Nicolas, PhD ’22 Microbiology. “When we added vitamin B12 to the soil, the composition of the bacterial community did not change, but the addition of alternate corrinoids caused distinct changes in the soil community,” notes Nicolas. 

According to Taga, this discovery opens the exciting possibility of using corrinoids to alter microbial communities and elicit healthier environmental and human health outcomes. The lab will now explore how individual bacteria interact with each other to form complex communities that impact carbon sequestration, human and plant health, and remediation of toxic chemicals.