Oberbach, A; Haange, SB; Schlichting, N; Heinrich, M; Lehmann, S; Till, H; Hugenholtz, F; Kullnick, Y; Smidt, H; Frank, K; Seifert, J; Jehmlich, N; von Bergen, M.
Metabolic in vivo labelling highlights differences of metabolically active microbes from the mucosal gastrointestinal microbiome between high fat and normal chow diet.
J Proteome Res. 2017;
- Autor/innen der Med Uni Graz:
The gastrointestinal microbiota in the gut interacts metabolically and immunologically with the host tissue in the contact zone of the mucus layer. For understanding the details of these interactions and especially their dynamics it is crucial to identify the metabolically active subset of the microbiome. This became possible by the development of stable isotope probing (SIP) techniques, which has only sparsely been applied to microbiome research. Here, we applied the in vivo stable isotope approach using (15)N labelled diet with subsequent identification of metabolically active bacterial species. Four-week old male Sprague-Dawley rats were randomly assigned to chow diet (CD, n =15) and high fat diet (HFD, n =15). After 11 weeks, three animals from each group were sacrificed for baseline characterization of anthropometric and metabolic obesity. The remaining animals were exposed to either a (15)N-labelled (n =9) or a (14)N-unlabelled experimental diet (n =3). Three rats from each cohort (HFD and CD) were sacrificed at 12 h, 24 h, and 72 h. The remaining three animals from each cohort, which received the (14)N-unlabelled diet, were sacrificed after 72 h. The colon was harvested, divided into three equal sections (proximal, medial and distal), the mucus layer of each specimen was sampled by scraping. We identified the active subset in a high fat diet (HFD) model of obesity in comparison to lean controls rats using metaproteomics. In addition, all samples were investigated by 16S rRNA amplicon gene sequencing. The active microbiome of the HFD group showed an increase of bacterial taxa for Verrucomicrobia and Desulfovibrionaceae. In contrast to no significant changes in alpha diversity, clearly time- and localization-dependent effects in beta-diversity were observed. In terms of enzymatic functions the HFD group showed strong affected metabolic pathways such as energy production and carbohydrate metabolism. In vivo isotope labelling combined with metaproteomics provides a valuable method to distinguish the active from the non-active bacterial phylogenetic groups which are relevant for microbiota-host interaction. For morbid obesity such analysis may provide potentially new strategies for targeted pre- or probiotic treatments.