Effects Of Six Probiotics On Acids Production During The Simulated Colonic Fermentation Of Three Dietary Fibers

Inulin, isomalto-oligosaccharides and xylo-oligosaccharides all belong to dietary fibers, and are considered as prebiotics. They can not be digested in the small intestine but fermented by the intestinal flora in the large intestine. Probiotics can utilize prebiotics via cell-attached extra-cellular hydrolases, change the compositions of the host intestinal flora, and thus confer colonic health. In the present study, the three dietary fibers were in vitro fermented by healthy adult fecal extract at 37 °C in the absence and presence of the selected six probiotics. Acetic, propionic and butyric acids generated in the fermentative systems during the colonic fermentation were detected by GC, to clarify the influences of fermentative substrates and the added probiotics on acid production, and to provide scientific evidence for the application of three dietary fibers and probiotics in functional foods. The main results are listed as below.(1) When inulin, isomalto-oligosaccharides and xylo-oligosaccharides were fermented by fecal extract at 37°C for 48 h respectively, they all were found to produce acetic acid in the greatest levels. And more, inulin and isomalto-oligosaccharides were also the suitable substrates to produce propionic acid, while xylo-oligosaccharides could result in more butyric acid production.(2) When inulin was fermented by fecal extract and six probiotics, in comparison of acetic acid production in the fermentative system containing inulin only, the added Enterococcus faecalis, Lactobacillus plantarum, L. rhamnosus and E. faecium increased acetic acid production by 35-91%. Addition of E. faecalis, L. brevis, L. rhamnosus and E. faecium increased propionic acid production by 15-34%, and addition of L. rhamnosus and E. faecium increased butyric acid production by 252%. However, addition of L. acidophilus showed the weakest ability to enhance three acids production in inulin-containing fermentative system.(3) When isomalto-oligosaccharides was fermented by fecal extract and six probiotics, addition of L. brevis, L. rhamnosus and E. faecium resulted in enhanced acetic acid production by 37-70%. Addition of L. brevis, L. rhamnosus, L. acidophilus and E. faecium enhanced propionic acid production by 51-122%. At same time, butyric acid production was increased by 140%-196%, when L. acidophilus, E. faecalis, L. rhamnosus and E. faecium were added. However, addition of L. plantarum had the weakest ability to enhance three acids production in the fermentative system.(4) When xylo-oligosaccharides was fermented by fecal extract and six probiotics, addition of five probiotics(but not L. acidophilus) increased acetic acid production by 66-82%, while addition of L. plantarum, L. rhamnosus and L. brevis resulted in more propionic acid production, and addition of L. brevis, E. faecalis and L. plantarum, butyric acid production was increased by 84-96%.(5) It was observed that dietary fibers-probiotics combinations, such as inulin-L. rhamnosus, inulin-E. faecium and xylo-oligosaccharides-L. plantarum combination, would produce more acetic acid. In total, inulin-L. brevis, inulin-L. rhamnosus, inulin-E. faecium and isomalto-oligosaccharides-E. faecium combinations could produce more propionic acid, while xylo-oligosaccharides-L.brevis, xylo-oligosaccharides-L. plantarum and xylo-oligosaccharides-L. faecalis combinations were more able to produce butyric acid.In conclusion, the three dietary fibers showed different abilities to produce three acids(acetic, propionic and butyric acids) during clonic fermentation, and addition of probiotics into fermentative system had effects on three acids production, which mostly could enhance three acids production to different levels.