The effects of selected Isomalto/malto-polysaccharides (IMMPs) on human microbiota composition and function during in vitro fermentation

Isomalto/malto-polysaccharides (IMMPs) are such a novel type of soluble dietary fibers with a prebiotc potential. These fibers are synthetized from starch by enzymatic conversion of (alpha 1 ? 4)-glucan bonds into (alpha 1 ? 6)-glycosidic linkages by the Lactobacillus reuteri 121 GTFB 4,6-alpha-glucanotransferase enzyme. The resulting (alpha 1 ? 6) linkages present in IMMPs make these fibers resistant to digestion by the human enzymes in the small intestine. Thus, this modified starch can pass undigested into the lower intestine where it is fermented by the resident microbes capable of breaking down the (alpha 1 ? 6) linkages. This property of the IMMPs makes them potentially interesting for the use as a prebiotic food ingredient capable of modulating the intestinal microbiota and exerting health promoting effects onto the host. Previous study reported increased production of the short chain fatty acids, especially acetate and propionate when IMMPs were used as a carbon source for microbial in vitro fermentation with human fecal inoculum as the microbial source. In this study we investigated the effects of IMMPs on the microbial composition and function during in vitro batch fermentations with fecal inocula from healthy human adults.