Beneficial contribution of the microalga Odontella aurita to the growth, immune response, antioxidant capacity, and hepatic health of juvenile golden pompano (Trachinotus ovatus)

Abstract

Under specific culture conditions, the marine diatom Odontella aurita can accumulate chrysolaminarin, which has antioxidant and anti-inflammatory functions, to improve immunity and regulating lipid metabolism. The current study investigated the use of chrysolaminarin-rich O. aurita as an immunostimulant in the diet of juvenile golden pompano Trachinotus ovatus. Three experimental diets containing 0%, 1% and 5% O. aurita were used to feed T. ovatus for 6-week. The results indicated that diet supplementation with O. aurita powder boosted the growth of T. ovatus by decreasing the feed conversion ratio, increasing the activities of lipase and pepsin in the intestine, and improving intestinal villi structure. Supplementation with 5% O. aurita promoted its antioxidant capacity by stimulating the Nrf2-ARE signal pathway and enhancing the total antioxidant capacity and activities of catalase, superoxide dismutase, and glutathione peroxidase. It also exerted hepatoprotective effects by inhibiting lipid deposition and downregulating the expression of proinflammatory cytokines and apoptosis-related genes, as well as improving the nonspecific immune response by increasing the expression levels of c-type lysozyme and complement 4. Therefore, a diet supplemented with 5% O. aurita is recommended to enhance the growth, antioxidant ability, and immunity of T. ovatus.