Effect of Human Faecal Donor on in Vitro Fermentation Variables

Abstract

Homogenized and diluted human faeces (66.6 g/l) collected from six individuals were incubated with four standard substrates (oat bran, wheat bran, kidney beans (Phaseolus uulgaris), and guar gum) for 4, 8, 12, and 24 h. Neutral detergent fibre (NDF) digestibility coefficients, short-chain fatty acid (SCFA) production (mmol/g organic matter (OM)), and gas production (ml/g OM) were significantly affected by donor, substrate, and donor X substrate interactions, within an incubation time, but substrate fermentability rankings were similar at 24 h for all six donors. Substrate differed in NDF digestibilities at all incubation times, whereas SCFA and gas productions differed only at 8, 12, and 24 h. The results indicate that inoculum source (donor) can influence in vitro fermentation variables but not the substrate fermentability ranking at 24 h. It is recommended that several donors, at least three, be used to improve the accuracy of in vitro estimates of colonic fermentation.

Key Words:

• Colonic fermentation
• dietary fibre
• faecal microbiota
• short-chain fatty acids