Bifidobacteria are important microbes in the gut, especially in early-life, but studying them is challenging. Now, researchers have developed new tools to better understand the role of Bifidobacterium breve, revealing its competitive growth strategies and potential for supporting the immune system.

The findings, published in Cell, may lead to better ways to use B. breve for improving health, in particular during infancy. The tools, the researchers say, “will catalyze future investigations of this important beneficial microbe.”

Bifidobacteria help with nutrition, immune system development and protecting against infections. However, these bacteria have specific growth requirements, needing certain conditions to thrive, and they are difficult to genetically manipulate. Bifidobacteria also interact with the gut in ways that are not fully understood, and species vary widely across individuals, making it difficult to draw conclusions about their effects.

Anthony Shiver at Stanford University in California and his colleagues developed a series of tools to better understand B. breve, exploring how it interacts with the body, how it grows, and how it produces helpful compounds.

Valuable resource

The researchers created more than 230,000 genetic mutations in B. breve to understand what each gene does. By tracking how these mutations affected the microbe’s survival, they identified key genes. 

Next, the team created a map of gene functions in B. breve by testing the mutant microbes in different environments, such as varying antibiotics and nutrients. The researchers also tested these mutants in animals with different diets to understand how Bifidobacterium survives and grows in the body, and they investigated the production of small molecules and the composition of Bifidobacterium’s cell wall. 

The mutant collection is a valuable resource for exploring the functions of individual genes in Bifidobacteria, the authors say.

Microbial competition

Using the tools they generated, the researchers found that B. breve mainly relies on plant-based carbohydrates for growth in the gut, and its ability to use these sugars is crucial for its survival and competition with other bacteria such as Bacteroides thetaiotaomicron. 

B. breve produces specific metabolites that are important for immune signaling, particularly in infants. These metabolites are produced by enzymes that help the microbe recycle energy, promoting its growth. 
The tools developed in this study could help researchers to better understand B. breve’s role in the gut, its competition with other bacteria and its response to stress, informing approaches to use this microbe to improve health, the authors say.