GC-TOF/MS-based metabolomics studies on the effect of protein sources in formulated diet for pearl oyster Pinctada fucata martensii

Natural disasters and environmental pollution are the main problems for traditional offshore culture. Pearl oyster culture through industrial farming can prevent these difficulties, but food availability is limited. In this study, we formulated two diets, P3 and P5, with yeast powder and corn gluten, respectively, as major protein sources. Two experimental groups (EG1 and EG2) were separately fed with P3 and P5 diets indoors. After 45 days of feeding, GC-TOF/MS-based metabolomics of the hepatopancreas was performed to assess the effect of different formulated diets on pearl oyster (Pinctada fucata martensii) combined with growth performance. EG1 displayed significantly faster absolute growth rate and higher survival rate than EG2. In the metabolomic assay, 125 metabolites were identified by mass spectrum matching with a spectral similarity value (SV) > 700, and 35 were considered significantly different metabolites (SDMs) (VIP > 1 and P < 0.05). Pathway analysis indicated that the SDMs were involved in 34 pathways, including seven influential pathways (pathway impact value > 0.1). The impact values of phenylalanine, tyrosine, and tryptophan biosynthesis, ascorbate and aldarate metabolism, phenylalanine metabolism, inositol phosphate metabolism, tyrosine metabolism, sulfur metabolism, and cysteine and methionine metabolism were 0.500, 0.500, 0.308, 0.219, 0.207, 0.167, and 0.161, respectively. Further integrated key metabolic pathway analysis showed that EG2 exhibited lower capability for inositol phosphate metabolism, ascorbate and aldarate metabolism, phenylalanine metabolism, and tyrosine metabolism. This study suggested that yeast powder is a better protein source of formulated diet for pearl oysters than corn gluten.