Effects of a short pulse administration of<i>Ulva rigida</i>on innate immune response and intestinal microbiota in<i>Sparus aurata</i>juveniles
Roberto Abdala‐Díaz, Jorge García‐Márquez, Rosa María Rico, Juan Luis Gómez‐Pinchetti, Juan Miguel Mancera, Félix L. Figueroa, Francisco Javier Alarcón, Eduardo Martínez‐Manzanares, Miguel Ángel Moríñigo
Abstract
Given the potential of algae as a new aquafeed ingredient, this study evaluated the effect of the tank-cultivated macroalgae Ulva rigida C. Agardh (Chlorophyta) on innate immune response, intestinal microbiota and their resistance against Photobacterium damselae subsp. piscicida in juvenile gilthead seabream (Sparus aurata L.) after a short pulse of administration. An algae-free diet was used as control, and an experimental diet was formulated containing 25% of U. rigida (UL-25). After 2, 7, 15 and 30 days biological samples were taken. No statistical significance (p > 0.05) was detected in respiratory burst activity. Diet UL-25 significantly enhanced alternative complement pathway activity respect to control diet from the beginning of the experiment (p < 0.05). When fish were challenged against P. damselae subsp. piscicida, UL-25-fed fish were more resistant against the pathogen than the fish fed control diet, obtaining a relative survival percentage of 54.55%. The ability of UL-25 diet to modify the intestinal microbiota was also confirmed. In conclusion, the use of a short pulse of dietary administration of 25% U. rigida in S. aurata diet modulates the immune response, intestinal microbiota and reduced the mortality rate during P. damselae subsp. piscicida infection.