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Dr Julian Marchesi  -  PhD


After graduating from Cardiff University I started work on looking at the impact of genetically modified microbes on natural ecosystems. At this point I developed an interest in the contribution of uncultured microbes to the maintenance and function of “natural” ecosystems i.e. molecular microbial ecology.  After this research position I continued to use molecular biological methods to investigate microbes in the deep biosphere ecosystem which exists below the sea-floor and developed molecular methods to investigate methane producing bacteria in this ecosystem.  

I followed this work with a Wellcome Trust Fellowship and extended my molecular microbial ecology interest to investigate, using culture independent methods, the diversity and distribution of genes involved in biodegradation of priority pollutants. It was during this period that I started turning my attention to using these molecular methods to explore the unculturable bacteria and their involvement in the human ecosystem.  

I obtained a Lectureship in the Department of Microbiology, University College Cork (UCC) and this provided me with the opportunity to investigate the contribution microbes make to gastrointestinal tract function.  In UCC my group investigated the human gut ecosystem in health and disease and used molecular methods to understand how bacteria contribute to the key functions which are found in human GI tracts.  

My current research interest is to continue this work in Cardiff and to further shed light on the contributions and role the human microbiome plays in health and disease.  The human microbiome consists of all the microbial genomes which are found in the human ecosystem.  The main fraction resides in the gastrointestinal tract and this collection of genetic information contains many functions which are able to influence the host’s own metabolism.  In fact the combined metabolic functions of these microbes are equivalent to that of the liver and we are now considering the gut microbiome as a virtual organ.  But unlike any conventional organ the range of functions are very dynamic and can be perturbed easily.  The gut microbiome has been implicated in many health and disease processes including obesity, non-alcoholic fatty liver disease and several atopic diseases.  Since this collection of microbes varies from one individual to another there exists the possibility that different individuals are being affected differently by their microbiome.