Electrospray alginate microgels co-encapsulating degraded Konjac glucomannan and quercetin modulate human gut microbiota in vitro

Alginate microgels co-encapsulating degraded Konjac glucomannan (KGM60) underwent in vitro fecal fermentation and their effects on human microbiota and metabolites were investigated. KGM60 delayed quercetin release and enhanced phenolic metabolites production. Microgels co-encapsulating KGM60 and quercetin increased linear short chain fatty acid but decreased branched chain fatty acid production. Microgels encapsulated with quercetin with or without KGM60 decreased Firmicutes while increased Bacteroidetes over 24 h of fermentation, at genus level promoted Bacteroides growth at 24 h and decreased the abundance of Negativibacillus, Ruminococcus_NK4A214, and Christensenellaceae R_7. Faecalibacterium and Collinsella levels were exclusively promoted by microgels encapsulating KGM60 with or without quercetin, highlighting prebiotic effect of KGM60. Only microgels co-encapsulating both KGM60 and quercetin enhanced Dialister while inhibited Lachnoclostridium, indicating synergism between KGM60 and quercetin. Our study indicates that co-encapsulating KGM60 and quercetin in alginate microgel is effective in modulating human gut microbiota and metabolites production potentially beneficial to gut health.