Dietary supplementation with polysaccharides from Rhizoma dioscoreae resulting in the enhanced immunity and the structural modulation of the intestinal microbiota in Luciobarbus capito

Abstract

Rhizoma Dioscoreas (R. dioscoreae), also known as Chinese yam, is a well-known edible and pharmaceutical plant in China. Yam polysaccharide (YP) is one of the main bioactive components of R. dioscoreae due to its decent medicinal and nutritional value. However, the underlying effect of YP treatment on Luciobarbus capito (L. capito) still remains unknown. Considering this, the current work aims to investigate the potential impact of different levels of YP treatment (i.e. 0.10 g/L, 1.00 g/L and 10.0 g/L) on L. capito in the context of the antioxidant enzyme activity, immune-related enzyme activity, digestive enzyme activity and intestinal microbiota. The activities of most antioxidant enzymes and immune-related enzymes were found to be generally increased after the varied doses of YP treatment, particularly for CAT, ACP and AKP (P < 0.05). This indicated that YP treatment could enhance the antioxidant activity and immune functions of L. capito via the modulation of various metabolic enzymatic activities. 16S rRNA gene amplicon sequencing data revealed that YP treatment can trigger dramatical alterations in the compositional structures of the dominant intestinal microbiota in L.capito, which could significantly increase the relative abundance of Aeromonas and decrease the relative abundance of Lactobacillus and Cetobacterium (P < 0.05). The global diversity of the intestinal microbiota of L. capito after different levels of YP treatment was found to be generally decreased, particularly reduced after 1.00 g/L YP treatment (P < 0.05). Functional predications revealed that there were no significant differences within different functional categories, including Biosynthesis category, Degradation/Utilization/Assimilation category, and Generation of Precursor Metabolites and Energy category, among others (P > 0.05). This work would be helpful to uncover the potential effect of YP treatment on L. capito and provide further insights into future utilization of YP as supplement to ameliorate the immunity and modulate the intestinal microbiota during the aquaculture process of L. capito.