Cobamide-based interactions between soil bacteria can be predicted based on monoculture growth.

Area of Science:

• Microbial Ecology
• Bacterial Interactions
• Nutrient Cycling

Background:

• Microbial community structure and function are shaped by complex interactions.
• Studying these interactions mechanistically is challenging due to the scale of co-occurring relationships.
• The model nutrient approach simplifies studying interactions by focusing on a single nutrient class.

Purpose of the Study:

• To investigate nutrient competition and sharing interactions using cobamides (vitamin B12 family) as a model nutrient.
• To examine interactions between cobamide-producing and cobamide-dependent bacteria.
• To predict microbial interactions in increasingly complex bacterial consortia.

Main Methods:

• Utilized co-culture and tri-culture experiments with grassland soil bacteria.
• Categorized bacteria as 'producers' (synthesize cobamides) or 'dependents' (require cobamides).
• Analyzed genomic metabolic capacity to identify key shared nutrients.

Main Results:

• Competition outcomes between dependent bacteria were predictable based on monoculture growth.
• Cobamide producers supported the growth of dependent bacteria in co-cultures.
• Producers influenced the competitive outcomes between dependent bacteria in tri-cultures, with cobamides identified as the primary shared nutrient.

Conclusions:

• Cobamides serve as a key shared nutrient mediating interactions in bacterial consortia.
• The model nutrient approach effectively characterizes and predicts microbial interactions.
• This approach is valuable for understanding bacterial consortia of varying complexity.