Dr. Douglas Brumley (University of Melbourne)

Abstract

Ocean nutrient cycling is driven by the concerted action of marine microbes, but the fine-scale interactions between these microbes and their physical and chemical environments remains elusive. I will present recent work which utilises a novel experimental platform for delivering sub-millimetre scale nutrient pulses, quantitatively mimicking those found in the ocean. Advanced video-microscopy is used to characterise microbial motion at the single cell level, and reveals the precise conditions under which bacteria can detect and climb dynamic nutrient gradients. New mathematical theory, based on the counting of individual molecules of dissolved organic matter, is in striking agreement with the experimental findings. From these quantitative foundations, we have developed a mechanistic framework for microbial motion, which directly unifies individual behaviour (cell motility, chemotaxis) with population-scale phenomena (collective nutrient uptake, competition between species). This provides a new path towards predicting ocean carbon cycling which is firmly based on micro-scale observations.

About the speaker

Douglas Brumley is a Lecturer in Applied Mathematics at The University of Melbourne. His studies span a range of length and time scales, from the dynamics of individual swimming microorganisms and the way they interact with one another, to the large scale flows around coral reefs. He uses microfluidic devices, fluorescent microscopy and high speed imaging in conjunction with mathematical models to investigate the fundamental physical principles in these systems and the role that behaviour at the microscale plays in determining macroscale observations in our oceans.

Website: https://www.douglasbrumley.com/