Abstract: Prebiotics can be used in fermented dairy products for improved sensory and textural properties, as well as enhanced health beneficial effects. In this study, the immunomodulatory effects of yogurt fortified with konjac mannanoligosaccharides (KMOS), a new type of functional oligosaccharides, were investigated in immunosuppressed BALB/C mice induced by cyclophosphamide (CTX). The results suggested that addition of KMOS enhanced the ability of yogurt to attenuate CTX-induced immunosuppression. Yogurt added with 0.5% (based on the weight of fresh milk) KMOS significantly improved the basic physiological state, the phagocytic activity of peritoneal macrophages, the proliferation rate of splenic lymphocytes, serum immunoglobulin concentration, and the release of inflammatory cytokines from peritoneal macrophages. Moreover, KMOS-fortified yogurt increased the relative abundance of non-dominant flora and the quantity of intestinal probiotics, and simultaneously suppressed the proliferation of Clostridium in the colon of immunosuppressed mice, thereby modulating the composition and structure of intestinal microbiota. These findings will provide useful information for the development of novel fermented milk products fortified with prebiotic oligosaccharides.

Key words: konjac mannanoligosaccharides; yogurt; immunosuppression; immunomodulatory activity; intestinal microbiota