Dr.Petra Louis - Diet and functional groups of the gut microbiota
Research focus
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 gene expression and cellular development of the colon.
Dietary intakes can influence the microbial gut community and shift the balance between different functional bacterial groups, with potential consequences for host health. My 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 I am 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.
Policy Briefings
Latest Publications
McIntosh FM, Maison N, Holtrop G, Young P, Stevens VJ, Ince J, Johnstone A, Lobley G, Flint HJ, Louis P (2012) Phylogenetic distribution of genes encoding β-glucuronidase activity in human colonic bacteria and the impact of diet on faecal glycosidase activities. Environ Microbiol 14: 1876-1877.
Louis P (2012) Does the human gut microbiota contribute to the etiology of autism spectrum disorders? Dig Dis Sci 57: 1987-1989.
Flint HJ, Scott KP, Duncan SH, Louis P, Forano E (2012) Microbial degradation of complex carbohydrates in the gut. Gut Microbes 3: 289-306.
Flint HJ, Scott KP, Louis P, Duncan SH (2012) The role of the gut microbiota in nutrition and health. Nat Rev Gastroenterol Hepatol 9: 577-589
Ze X, Duncan SH, Louis P, Flint HJ (2012) Ruminococcus bromii is a keystone species for the degradation of resistant starch in the human colon. ISME J 6: 1535-1543.
Scott KP, Duncan SH, Louis P, Flint HJ (2011) Microorganisms in the human gut. The Biochemist 33 (4): 4-9.
Scott KP, Duncan SH, Louis P, Flint HJ (2011) Nutritional influences on the gut microbiota and the consequences for gastrointestinal health. Biochem Soc Trans 39: 1073-1078
Flint HJ, Duncan SH, Louis P (2011) Impact of Intestinal Microbial Communities upon Health. In: Beneficial microorganisms in multicellular life forms. E Rosenberg and U Gophna (eds). Springer-Verlag Berlin Heidelberg, pp. 243-252.
Walker AW, Ince J, Duncan SH, Webster LM, Holtrop G, Ze X, Brown D, Stares MD, Scott P, Bergerat A, Louis P, McIntosh F, Johnstone AM, Lobley GE, Parkhill J, Flint HJ (2011) Dominant and diet-responsive groups of bacteria within the human colonic microbiota. ISME J 5: 220-230.
Eeckhaut V, Van Immerseel F, Croubels S, De Baere S, Haesebrouck F, Ducatelle R, Louis P, Vandamme P (2011) Butyrate production in phylogenetically diverse Firmicutes isolated from the chicken cecum. Microbial Biotechnology 4: 503-512.