Better in captivity or wild? Upside-down jellyfish as potential biofactories

The zooxanthellate jellyfish Cassiopea andromeda is among the first marine immigrant that over 100 years ago crossed the Suez Canal to become established in the Mediterranean Sea. We previously demonstrated that it contains valuable bioactive compounds such as fatty acids (mainly PUFAs as DHA, EPA, and oleic acid) and pigments produced by the photosyntethic dinoflagellates hosted as endosymbionts. Here we compared jellyfish cultured under laboratory conditions with wild specimens sampled in Sicily, Italy, for a) the hosted symbionts' molecular identity, number and density, and for b) their content of protein, phenols, lipids and pigments in the holobiont biomass. Using an established protocol, total extracts and their fractions were biochemically characterized and analyzed for their antioxidant activity. We found wild jellyfish showed a higher content of proteins, lipids and a richer composition of polyunsaturated fatty acids, whereas cultured jellyfish showed a higher content of phenols and antioxidant activity. We discuss the role of the endosymbiotic dinoflagellate metabolism in determining the Cassiopea holobiont biochemical composition, and the possible improvement of rearing conditions, also in light of their potential application as functional food, feed, and as source of bioactive compounds, in line with the goals of the blue-green economy.