Prebiotic activities of dextran from <i>Leuconostoc mesenteroides</i> SPCL742 analyzed in the aspect of the human gut microbial ecosystem

Abstract

The aim of this study was to investigate the prebiotic activities of dextran (LM742) produced by <i>Leuconostoc mesenteroides</i> SPCL742 in the aspect of the human gut microbial ecosystem focusing on microbiome and metabolome changes in <i>in vitro</i> colonic fermentation. LM742 dextran had a medium-chain structure with the molecular weight of 1394.87 kDa (DP = 7759.22) and α-1,6 and α-1,3 linkages with a 26.11 : 1 ratio. The LM742 dextran was resistent to digestive enzymes in the human gastrointestinal conditions. The individual cultivation of 30 intestinal bacteria with LM742 dextran showed the growth of <i>Bacteroides</i> spp., whereas <i>in vitro</i> human fecal fermentation with LM742 exhibited the symbiotic growth of <i>Bacteroides</i> spp. and beneficial bacteria such as <i>Bifidobacterium</i> spp. Further co-cultivation of <i>Bacteroides xylanisolvens</i> and several probiotics indicated that <i>B. xylanisolvens</i> provides a cross-feeding of dextran to probiotics. In fecal fermentation, LM742 dextran resulted in increased concentrations of short-chain fatty acids, valerate and pantothenate, but it rarely affected the conversion of betaine to trimethylamine. Lastly, LM742 dextran inhibited the adhesion of pathogenic <i>E. coli</i> to human epithelial cells. Taken together, these results demonstrate the prebiotic potential of LM742 dextran as a health-beneficial polysaccharide in the human intestine.