Metagenomic insights into the energy metabolism and immune variation of sea cucumber Apostichopus japonicus during reproduction

Gut microbiota plays an important role in life activity of host. It is well known that the energy requirement of broodstock increased and the immunity of broodstock decreases during reproduction. However, the function of intestinal microbiota in the energy and immune during reproductive period is still not cleared. In this study, metagenomic analysis of the gut inclusions of sea cucumber Apostichopus japonicus investigated those variations of the gut microorganism and KEGG pathways.Results suggested that the ratio of Firmicutes/Bacteria is closely relate to gain energy and energy metabolite, the ratio of F/B also different in different genders, The immunity decreased and pathogenic bacteria increased in gonadal growth stage. Post spawning, immunity of A. japonicus decreased, the ratio of probiotics is increase, it supplements depressed immune. In different genders, several KEGG pathways varied and different significantly between female and male, such as Metabolic pathways, Biosynthesis of secondary metabolites, Biosynthesis of amino acids, Oxidative phosphorylation and Fatty acid metabolism. the trade of Oxidative phosphorylation is similar to Metabolic pathways. This study provided an important information for breeding and application in aquaculture of A. japonicus.