Selection of probiotics and prebiotics for synbiotics and confirmation of their in vivo effectiveness

Influence of fructan-type oligosaccharides (as prebiotics) on growth and acidifying activity of Bifidobacterium strains (as probiotics) was studied in vitro, using minimal nutrition media. The selected synbiotic pairs of stimulated bifidobacteria strains and oligosaccharides enhancing their growth were studied in vivo to determine the effect of probiotics, prebiotics and synbiotics on microecology of gut. Daily, > 10(9) live cells of bifidobacteria strains and/or 5% (w/w) of oligofructose in the diet were orally administered to Wistar rats. After a 14-day feeding experiment, the numbers of faecal bifidobacteria, aerobic and facultatively anaerobic bacteria, coliforms, and spores of anaerobic and aerobic bacteria were determined using microbiological methods. In vitro studies showed that the majority of Bifidobacterium species utilised FOS and low-polymerised inulins, but only 18 out of 30 strains tested (mostly of B. longum and B. animalis species) were stimulated. Incorporation of oligofructose into the diet stimulated the proliferation of faecal bifidobacteria by 1.6 log cfu/g in comparison to the control. B. longum KN29.1 and KNA1 selected in vitro, slightly increased the faecal bifidobacteria live cell number by about 0.6 log cfu/g under in vivo conditions, whereas B. animalis KSp4 was not effective. But administration of bifidobacteria together with the prebiotic (as synbiotics) improved the bifidogenic effect by 1.4 log cfu/g of faeces. Supplementation of diet had almost no effect on the other determined groups of gut microflora. The obtained results showed the selective stimulation of faecal bifidobacteria by probiotics, prebiotic and synbiotics, a great bifidogenic effectiveness of oligofructose, confirmed proper selection of synbiotics and showed their higher effectiveness in relation to probiotics. (C) 2002 Elsevier Science Ltd. All rights reserved.