The impact of fluid motion on microbial ecology: phytoplankton patchiness and bacterial biofilm development in porous media.

Dr. Mack Durham (Oxford University)

Thursday 24th January, 2013 14:00-15:00 203


While many microorganisms spend their lives in moving fluids, their local fluid dynamical environment is often ignored when characterizing important ecological processes such as competition, predation, and the maintenance of diversity. In this talk, I will present laboratory experiments and mathematical models that illustrate how flow shapes the ecology of phytoplankton and bacteria by driving heterogeneity in their spatial distribution. First, I will show how coherent and turbulent fluid shear triggers the aggregation of vertically migrating phytoplankton into layer and patch structures, respectively. These structures are routinely observed in the field and have a profound impact on phytoplankton population dynamics. Second, will present recent experiments in which Escherichia coli is inoculated in patterned microfluidic devices that simulate a porous soil environment. We find biofilm patches undergo a self-organization mediated by the interaction of growth and flow, leading to the formation of preferential flow channels at intermediate flow rate. This mechanism is found to strongly modulate overall biofilm productivity and may have implications on the maintenance of bacterial diversity in porous systems.

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