Enrichment of bifidobacteria from human gut contents by oligofructose using continuous culture.

Chemostat cultures of human faecal bacteria were used to determine the bifidogenic effect of oligofructose, a fermentable carbohydrate found in a number of plants. In single stage continuous culture, oligofructose preferentially enriched for bifidobacteria, in comparison to sucrose and inulin. This stimulatory effect was enhanced at a high dilution rate, high substrate concentration and low pH. These parameters are likely to approximate to those that occur in the proximal colon. Studies with a three-stage continuous culture model of the large intestine confirmed the bifidogenic effect of oligofructose. These in vitro data indicate that an increase in the concentration of fructose-based oligosaccharides in the diet may alter the balance of the gut microflora towards bifidobacteria, a purported health-promoting genus.