Depolymerized RG-I enriched pectin from citrus segment membrane modulates gut microbiota, increases SCFAs production, promotes the growth of Bifidobacterium spp., Lactobacillus spp. and Faecalibaculum spp.

Rhamnogalacturonan-I (RG-I) enriched pectin (WRP) was recovered from citrus processing water by sequential acid and alkaline treatment in a previous study. RG-I enriched pectin was proposed as a potential supplement for functional food and pharmaceutical development. However, previous studies illustrated favorable modulations of gut microbiota by RG-I enriched pectin were based on in vitro, changes in the overall microbial structure and whether there is a structure-dependent way in modulation of gut microbiota remain largely enigmatic. In the present study, modulations of gut microbiota by commercial pectin (CP), WRP and its depolymerized fraction (DWRP) with different RG-I content and Mw were compared in vivo. Revealed by 16s rRNA high-throughput sequencing, WRP and DWRP mainly composed of RG-I, modulated the gut microbiota in a positive way. WRP significantly increased the abundance of prebiotic such as Bifidobacterium spp., Lactobacillus spp., while DWRP increased SCFAs producers including species in Ruminococcaceae family. By maintaining more balanced gut microbiota composition and enriching some SCFA producers, dietary WRP and DWRP also elevated SCFAs content in the colon. Collectively, our findings offer new insight into structure-activity correlation of citrus pectin and provide impetus towards the development of RG-I enriched pectin with small molecular weight for specific use in health-promoting prebiotics ingredient and therapeutic.