Senior Research Fellow
The microbial community in the human large intestine consists of a diverse range of bacteria that break down complex nutrients of dietary and host origin. The members of this ecosystem form a complex metabolic network in which the product of one group can serve as substrate for another group. Overall, this leads to the accumulation of mainly three organic acids, acetate, propionate and butyrate, which are partially absorbed by the colon and serve as an additional energy source for the human host. Butyrate is of special interest, as it serves as the preferred energy source for the colonic wall and thus contributes to the proper functioning of the gut. It has also been claimed to be protective against colon cancer and inflammatory bowel disease through effects on host gene expression and cellular development of the colon. Propionate also influences host physiology and its potential effects on host satiety is of particular interest in view of the current obesity epidemic.
Dietary intakes can influence the microbial gut community and shift the balance between different functional bacterial groups, with potential consequences for host health. Our research concentrates on assessing those changes using molecular techniques, especially quantitative PCR against the 16S rRNA gene as a phylogenetic marker, with a view to establishing the effect of different diets on gut health. In addition we are developing degenerate PCR approaches against functional genes that can be used as phylogenetic markers for specific functional groups of bacteria. This has been successfully applied to investigating the butyrate-producing community in response to intake of the prebiotic inulin (Louis et al, 2010). A further area of interest is the release of dietary plant phenolics from their glycosidic parent compounds by the gut microbiota, which is an essential step in facilitating their health-promoting activities. Techniques used in my lab range from molecular phylogeny and metagenomics to microbial physiology and biochemistry.