In Vitro Kinetic Analysis of Fermentation of Prebiotic Inulin-Type Fructans by Bifidobacterium Species Reveals Four Different Phenotypes

Abstract

Kinetic analyses of bacterial growth, carbohydrate consumption, and metabolite production of 18 Bifidobacterium strains grown on fructose, oligofructose, or inulin were performed. A principal component analysis of the data sets, expanded with the results of a genetic screen concerning the presence of a ␤-fructofuranosidase gene previously encountered in Bifidobacterium animalis subsp. lactis DSM 10140 T , revealed the existence of four clusters among the bifidobacteria tested. Strains belonging to a first cluster could not degrade oligofructose or inulin. Strains in a second cluster could degrade oligofructose, displaying a preferential breakdown mechanism, but did not grow on inulin. Fructose consumption was faster than oligofructose degradation. A third cluster was composed of strains that degraded all oligofructose fractions simultaneously and could partially break down inulin. Oligofructose degradation was substantially faster than fructose consumption. A fourth, smaller cluster consisted of strains that shared high fructose consumption and oligofructose degradation rates and were able to perform partial breakdown of inulin. For all strains, a metabolic shift toward more acetate, formate, and ethanol production, at the expense of lactate production, was observed during growth on less readily fermentable energy sources. No correlation between breakdown patterns and the presence of the ␤-fructofuranosidase gene could be detected. These variations indicate niche-specific adaptation of bifidobacteria and could have in vivo implications on the strain specificity of the stimulatory effect of inulin-type fructans on bifidobacteria.

Mutual Cross-Feeding Interactions between Bifidobacterium longum subsp. longum NCC2705 and Eubacterium rectale ATCC 33656 Explain the Bifidogenic and Butyrogenic Effects of Arabinoxylan Oligosaccharides

“…Indeed, in Bifidobacterium spp., pyruvate can be converted into formate, acetate, and ethanol (Fig. 4), at the expense of lactate, to respond to a higher energy demand when growing on complex carbohydrates, which results in a lower growth rate and a shift from lactate production to mixed acid production (12,37,(50)(51)(52). The production of additional ethanol allowed the B. longum strain to regenerate more NAD ϩ , which is important for continuation of the upper pathways.…”

In Vitro Kinetics of Prebiotic Inulin-Type Fructan Fermentation by Butyrate-Producing Colon Bacteria: Implementation of Online Gas Chromatography for Quantitative Analysis of Carbon Dioxide and Hydrogen Gas Production

“…Residual concentrations of glucose, fructose, oligofructose, and inulin (the latter two expressed in mM FE), as well as concentrations of acetate, butyrate, ethanol, formate, and lactate were determined through high-performance liquid chromatography as described previously (19). All samples were analyzed in triplicate.…”

“…Consequently, they might be responsible for an enhancement of gas production as a result of fructan fermentation, through either cross-feeding or direct degradation of inulin-type fructans (15,16). Indeed, inulin-type fructan consumption has been reported to cause some gastrointestinal discomfort related to gas productionessentially, flatulence and bloating (43)-while bifidobacteria, the main beneficiaries of dietary fructan intake, do not produce gases (19,49). Although CO 2 and H 2 production by colon butyrate producers could have implications for human intestinal well-being, (in vitro) production has not been satisfactorily monitored up to now, probably due to limited availability of a performant apparatus for (online) gas analysis (15,20).…”

“…A major challenge of gastrointestinal microbiology lies in linking phylogenetic subgroups with particular ecological habitats and niches (7,8,23). The latter requires further development of highly discriminating 16S rRNA gene-targeted probes to monitor spatial bacterial distribution, combined with renewed efforts toward species isolation through the application of innovative cultivation methods and media, and extensive metabolic characterization of representative strains (19,35,48).…”

Fructo-Oligosaccharide Synthesis by Mutant Versions of Saccharomyces cerevisiae Invertase

“…Moreover, the relative behavior of different species is also conditioned by the chemical nature of the FOS (type of fructosyl-fructose linkages and degree of polymerization). When using inulin-type or levan-type FOS as the sole carbon source, different bifidobacteria species show diverse phenotypes regarding growth rates and patterns of synthesized metabolites (lactate, acetate, formate) (13,23). This observation may raise the possibility of modulating the colon microbiota by specific FOS compositions.…”