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The kinetics of inulin-type fructan degradation is examined by representatives of the genera Anaerostipes and Roseburia and a method based on online gas chromatography (GC) is developed for assessing gas production in a continuously sparged fermentation vessel for complete coverage of metabolite production. The complete recovery of metabolites during fermentations of Clostridial cluster XIVa butyrate-producing colon bacteria has allowed stoichiometric balancing of the metabolite pathway for butyrate production, including the formation of [H.sub.2].

An in vitro competitiveness trials with bifidobacterial strains belonging to the different phenotypical clusters are designed to study the fructan degradation capacity of B. thetaiotaomicron LMG 11262 growing on oligofructose or inulin. The results indicated that different groups of inulin-type-fructan prebiotics might stimulate distinct subgroups of the large-intestinal Bifidobacterium population, a variation that could be reflected in differences concerning their health-promoting effects.

The bacterial growth, carbohydrate consumption and metabolite production of Bifidobacterium strains grown on fructose, oligofructose or inulin are kinetically analyzed. The variations have shown niche-specific adaptation of bifidobacteria and have in vivo implications on the strain specificity of the stimulatory effect of inulin-type fructans on bifidobacteria.

Interspecies interactions are studied by performing in vitro coculture fermentations of Bifidobacterium longum BB536 and two acetate-converting, butyrate-producing colon bacteria, Anaerostipes caccae DSM 14662 and Roseburia intestinalis DSM 14610, with oligofructose as the sole energy source. It is found that the cross-feeding mechanisms could play a role in the colon ecosystem and contribute to the combined bifidogenic/butyrogenic effect observed after addition of inulin-type fructans to the diet.