Microbial Interactions at the Microscale

Microbes live in a small world where interactions between members of a community are short-ranged. To study the spatial and functional organization of microbial communities at the microscale, we we combine microfluidics with time-lapse microscopy. The resulting insights into growth rates and ecophysiology at the single-cell level allows us to understand how microbes behave and interact with each other and how they respond to changing environmental conditions.

Metabolic interactions in spatially structured microbial communities

Microfluidic chamber with two fluoresclently labelled E. coli strains — Two auxotrophic *E. coli* strains engage in cross-feeding. Individual cells can be segmented and tracked using Midap, our automated image analysis software.

Microbial communities exhibit complex networks of interactions, where the metabolic output of one member affects the growth of another. To better understand these networks in spatially structured communities, our research explores:

The evolution of cell-cell interactions in spatially structured synthetic microbial communities (Divvya)
The role of non-growing but metabolically active members in microbial communities (Gatwa)

Group behavior and collective nutrient breakdown

Caulobacter crescentus growing on xylan — As *Caulobacter crescentus* grows on the polysaccharide xylan if forms clusters. Cells are false-coloured according to their lineage.

Microbial primary degraders mediate carbon cycling in nearly every environment on Earth. As such, their activities profoundly shape our climate. Degraders have evolved two fundamentally different strategies for achieving polysaccharide degradation -- extracellular versus intracellular hydrolysis -- which are subjected to different tradeoffs and exert different ecological and biogeochemical impacts in the environment. To better understand how degraders are (and will continue) shaping the fate of carbon in different ecosystems, our research is exploring how different degradation strategies influence degraders' growth and function under different environmental conditions, with specific emphasis on marine particle turnover dynamics. We investigate:

How do different microbial polysaccharide degradation strategies (i.e., extracellular vs. intracellular hydrolysis) influence degrader growth and organic matter turnover under different environmental conditions? (Shae)