Factors affecting microbial metabolism in a human fecal fermentation model to evaluate prebiotics

In vitro fermentations using human fecal bacteria are an often used high through put strategy to evaluate the prebiotic potential of food ingredients. We investigated the influence of the substrate presented to fecal microbiota by monitoring the microbial short chain fatty acid production. We also examined the impact of cryopreserved glycerol stocks of feces on the performance of multiple batches of fermentations to examine the feasibility of using standardized inocula for multiple batches. Both composition and concentrations of bioactives (dietary fibre, polyphenols) were found to influence the metabolic capacity of human fecal microbiota. We also found that feces preserved at −80 °C provided a consistent and stable inoculum for performing batch fermentations for a duration of up to 3 years.