Human fecal microbiome before and after consumption of a prebiotic galactoologosaccharide, a probiotic (IVS-1 or BB-12), or the synbiotic combination-Raw 16S rRNA sequence reads

One way to improve both the ecological performance and functionality of probiotic bacteria is by combining them with a prebiotic in the form of a synbiotic. However, the degree to which such synbiotic formulations improve probiotic strain functionality in humans has not been tested systematically. Our goal was to use a randomized, double-blind, placebo-controlled, parallel-arm clinical trial in obese humans to compare the ecological and physiological impact of the prebiotic galactooligosaccharides (GOS) and the probiotic strains Bifidobacterium adolescentis IVS-1 (autochthonous and selected via in vivo selection) and Bifidobacterium lactis BB-12 (commercial probiotic allochthonous to the human gut) when used on their own or as synbiotic combinations. Following three weeks of consumption, strain specific quantitative real-time PCR and 16S rRNA sequencing were performed to assess changes in the microbiota. IVS-1 reached significantly higher cell numbers in fecal samples than BB-12 and its administration induced an increase in total bifidobacteria that was comparable to that of GOS. Both probiotic strains showed a consistent but non-significant trend of higher fecal cell numbers when administered with GOS, and the OTU representing strain IVS-1 but not BB-12 was significantly enhanced in the synbiotic group when compared to the probiotic alone. This study demonstrated that 'autochthony' of the probiotic strain has a larger effect on ecological performance than the provision of a prebiotic substrate.