A fecal-culture model, monitoring gas production, for assessing prebiotics' fermentability in normal-weight and obese subjects

Abstract

[Background/Aims] The gut microbiota is altered in different conditions, which leads to the interest in prebiotics to restore it and to identify the best suited compounds. The use of fecal culture models provides an interesting strategy, allowing to identify prebiotics with suitable fermentation profiles, and appropriate microbiota-modulation properties, for each population. Here we aimed at comparing the fermentability and microbiota-modulation ability of different prebiotics, including the novel prebiotic 1-Kestose, in normal-weight and obese adults. [Methods] Fresh fecal samples from 9 normal-weight (BMI< 25kg/m2) and 10 obese (BMI> 40) volunteers were collected, transported to the laboratory (under anaerobic conditions), homogenized, diluted (10% v/v) into a carbohydrate-free basal medium and stabilized at 37°C in an anaerobiosis cabinet. The prebiotics tested (Actilight, Synergy, P95, Inulin, GOS and 1-kestose) were added (0.3%, w/v) to the stabilized fecal cultures and incubated at 37°C for 24 hours. Gas production along incubation was monitored in real-time by using the ANKOM RF System. Samples were taken at 0 and 24 hours of incubation for pH measurements, determination of short-chain-fatty-acids by gas chromatography and gut microbiota analyses by qPCR. [Results] In both volunteers’ groups kestose resulted the more fermentable prebiotic as indicated by the largest accumulation of gas and the lowest pH after incubation. On the contrary, inulin was the less fermentable compound. Interestingly, intestinal microbiota from obese individuals tended to show a lower ability to produce gas than that from normal-weight volunteers. The different prebiotics were able to induce changes in microbiota composition in both volunteer groups, although showing differences among them. [Conclusions] The fecal culture model used, with real-time monitoring of gas production, constitutes a fast and easy method for assessing the fermentability of prebiotics in different population groups. 1-kestose showed good characteristics suggesting its applicability as a readily fermentable prebiotic substrate for intestinal microbiota modulation.