An experimental model for the spatial structuring and selection of bacterial communities.

Area of Science:

• Evolutionary Biology
• Microbial Ecology
• Experimental Evolution

Background:

• Community-level selection is theorized to emerge in spatially structured environments.
• Bacterial interactions and spatial structuring are key to understanding microbial community dynamics.

Purpose of the Study:

• To experimentally model and test community-level selection in spatially structured bacterial communities.
• To investigate the role of coaggregation in bacterial competition under grazing pressure.

Main Methods:

• Developed an experimental model using coaggregating bacterial strains (Blastomonas natatoria and Micrococcus luteus).
• Applied protozoan grazing as a selection pressure in a continuous culturing system.
• Assessed the relative fitness of different Blastomonas natatoria strains.

Main Results:

• A slow-growing strain, Blastomonas natatoria 2.1, which coaggregates with Micrococcus luteus, outcompeted a fast-growing strain, Blastomonas natatoria 2.8.
• Spatial structuring via coaggregation conferred a competitive advantage under protozoan grazing pressure.

Conclusions:

• Spatial structuring can drive community-level selection in bacteria, favoring strains that benefit from physical associations.
• These findings have implications for the evolution of bacterial communities in natural, heterogeneous environments.