Microbial ecology and nutrient cycling

I have a long-running collaboration with Dr. Andrew Free of the School of Biological Sciences in Edinburgh, on a joint experimental/simulation project to understand community assembly and community composition in self-sustaining microbial ecosystems.

In our experiments, we set up and analyse Winogradsky Columns - plastic tubes containing pond sediment and water, as well as nutrients, which are exposed to light for a period of weeks or months. These microcosms develop into self-sustaining ecosystems with vertical redox gradients, which cycle sulphur and carbon, as well as other nutrients. We use modern molecular techniques to measure the species composition of these microbial communities and we also measure their chemical composition using voltammetry.

Among other things, we have investigated whether replicate microcosms are identical in their community development. In parallel with this experimental work, we have also developed theoretical and computational models for the population dynamics of the microbes in nutrient-cycling ecosystems. These models have looked at how small population number fluctuations can have a dramatic effect on long-time dynamics, and also, more recently, how non-linearities in microbial population dynamics can cause drastic changes in chemical and species composition in response to environmental perturbations.