One‑carbon nutrients and genistein as nutritional programming effectors in juvenile gilthead seabream (Sparus aurata): Contrasting effects on phenotypic traits

Several studies have been conducted on the nutritional programming of farmed fish. Genistein (GEN) and one‑carbon nutrients (1C) produce different epigenetic effects, being suitable candidates as nutritional programming effectors. We fed juveniles of the gilthead seabream with a control and with 1C-micronutrients and genistein enriched feeds for 2 months, and then with a commercial diet for 4.5 months in common garden tanks. Similar fish performance was obtained with 1C and GEN diets, but resulted in different basal levels of cortisol, which conditioned the stress response. In addition, GEN increased hepatic reactive oxygen species (ROS) and lipid peroxidation, but all these effects fade after 4.5 months. Also, 1C and GEN made the behavioral traits of fish to diverge, with 1C fish being bolder and GEN fish shyer, but these behaviors were even emphasized with time. Finally, 1C and GEN affected diversity indices and taxonomic composition of the intestinal microbiota. After 4.5 months on a commercial diet, a clear separation of experimental groups was still observed, with a higher relative abundance of the vitamin B-producer bacteria family Rhodobacteraceae in 1C fish, and specifically, the genus Sulfitobacter . This study reveals the positive effects of increased 1C micronutrient content in feed for gilthead seabream juveniles on stress resistance, antioxidant status and behavioral traits, and it is the first providing evidence of a programming effect at the juvenile stage on microbiota composition and behavioral traits. More research is needed to increase the scope of GEN and 1C effects and to understand the underlying mechanisms. • Dietary 1C-nutrients improve stress resistance and antioxidant status. • Dietary 1C-nutrients increase intestinal microbiota richness. • 1C-nutrients program for higher abundance of vitamin B-producer Sulfitobacter . • Dietary genistein and 1C-nutrients program for divergent fish risk-taking behavior.