Microbial ecology, the interaction of microorganisms with their environment, is an essential component in understanding the functioning of the global ecosystem. Tom Fenchel, a leading Danish microbial ecologist, defined the aim of microbial ecology as “...to find principles that explain the structure and function of microbial communities. Only when these principles are understood will the full impact of microbial activity on the global ecosystem be apparent.

Dr Purdy’s research focuses on seeking principles that explain microbial ecology in two main areas:

• Understanding fundamental ideas in microbial ecology, particularly to do with the relationship between microbial community structure and function;
• Studying communities involved in global biogeochemical cycling.

Fundamental ideas in microbial ecology

However, microbial ecology lacks a strong fundamental basis and as a result much of the work in this field has been primarily descriptive. By their nature microbes are difficult to identify, quantify and, in many cases, grow in the laboratory, making the study of their ecology a difficult task. Microbial ecology lacks the firm theoretical basis of traditional ecology and, as a result, has suffered from being empirical in nature and descriptive in practice [11]. Thus, it is essential to build the theoretical basis of microbial ecology with studies on fundamental aspects of microbial diversity and in situ function.

In order to begin the process of building the fundamentals of microbial ecology the groups research is focused in two areas: studying microbial distribution and ecology along natural environmental gradients (tidal estuaries) and on the distribution and function of methanogenic archaea in termite guts. Both systems are used as models, the estuaries are dynamic systems of continuous variation in a number of facts while termites represent more stable systems that vary substantially from species to species.

Present projects:

MicroComXT: Microbial ecology: the relationships between community diversity, structure and function

This €1.35M project is funded by the European Commission under Framework Programme 6. It has two strands of research: Understanding the relationship between genotypic and phenotypic distribution ecology and Investigating the stability and plasticity of genotypes and phenotypes. The Team presently consists of the Team Leader (Dr Purdy), a senior post-doctoral researcher (Dr Brian Oakley) and two PhD students, Franck Carbonero and Alessandra Natale.

Nitrous oxide and nitrogen gas production in the Arabian Sea – a process and community based study

This NERC-funded project is in collaboration with Dr Mark Trimmer at Queen Mary College, University of London. Our understanding of the nitrogen cycle has undergone a revolution in the past 10 years. The discovery of anaerobic ammonia oxidation and the discovery that marine crenarchaea can aerobically oxidise ammonia has fundamentally altered the way we view this vital biogeochemical cycle. In this project we will investigate the link between the production of nitrous oxide, a potent greenhouse gas, and anaerobic ammonia oxidation. We will visit the vast and ecologically important Oxygen Minimum Zone in the Arabian Sea to measure the processes that occur there, experimentally test specific hypotheses about the relationship between N2O and N2 production in situ as well as using a suite of molecular methods to determine the identities of the organisms involved in nitrogen cycling. The project, which should begin in 2008, will employ a Post-Doctoral researcher (Dr Jo Nicholls) at Queen Mary and a PhD student here at Warwick.

Role of methanogens in the evolution and ecophysiology of termites

In collaboration with Dr Paul Eggleton at the Natural History Museum in London we have been investigating the relationship between termites and their gut methanogens. There is strong evidence that links methane production in termite guts with the feeding guild the termites belong to. Wood/grass and fungus feeding termites produce very little methane, while humus and soil feeding termites produce far more. As switching between different feeding guilds has occurred in closely related termite species these represent a natural model evolutionary and ecological system to address questions of adaptation to environments, rates of evolutionary change as well as the role microbes may play in the development and evolution of larger organisms.