Fermentation in the large intestine unravelled using 13C-labelled substrates Implications for obesity and gut health
bookPart
The colon is one of the body's metabolically most active organs. While insight in colonic microbial diversity increases, little is known about the metabolic function of the microbes, the way diet affects metabolic fluxes, and how the metabolites that are produced affect obesity or gut health. 13C-stable isotope labelling of substrates was employed with the aim to investigate the activity of the colonic microbiota in detail. The TNO in vitro model of the colon (TIM-2) was inoculated with a standardised adult human faecal microbiota. The substrates (starch, inulin or lactose), uniformly labelled with the stable isotope 13C, were added, and samples were taken at various time points for analysis. LC-MS and NMR techniques were used to identify microbial metabolites and to analyse their 13C contents. Mathematical modelling of isotopomer distributions was used to build a flux model. 16S rRNA-Stable Isotope Probing (SIP) was employed to study the incorporation of label in the biomass of those members of the microbiota that fermented the substrates. Using these techniques direct links could be established between metabolites produced and the micro-organisms responsible for their production. This type of detailed information about the fermentation of substrates in the context of a complex microbiota can only be obtained through the use of stable isotope labelled substrates. For instance, the exact amount of kcal/g substrate after fermentation can be determined, and thus also the role of the microbiota in obesity can be assessed in detail. In addition, the effect of microbial metabolites on gut health can be assessed. For this we have developed sophisticated gastroenterological tools to sample the colon in (healthy) human volunteers. The combination of these techniques holds great promise to unravel the processes occurring in the colon and linking them to health and disease. © Wageningen Academic Publishers The Netherlands, 2010.
TNO Identifier
954146
ISBN
9789086861286
Publisher
Wageningen Academic Publishers
Source title
Dietary Fibre: New Frontiers for Food and Health
Editor(s)
Kamp, J.W. van der
Jones, J.
McCleary, B.
Topping, D.
Jones, J.
McCleary, B.
Topping, D.
Place of publication
Wageningen
Pages
539-554
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