Abstract

The use of high protein microalgae obtained by increasing the content of nitrate in the culture medium is recommended to improve the performance of broodstock, larvae and juveniles in bivalve hatchery. However, the effect of these concentrations of nitrate on the composition of fatty acids in microalgae is not known and it is relevant to assess possible changes in its nutritional properties for filtering bivalves. The results of nitrate increase in Isochrysis aff. galbana (clone T-Iso) showed that in the high nitrate medium, T-Iso is high in protein and carbohydrate and low in ash, and also exhibits higher values of polyunsaturated fatty acids (PUFA), especially n-3PUFA. The best culture medium for Tetraselmis suecica would also be the one high in nitrate because of it is high in protein and lipid and low in ash, although the best values PUFA were observed in the standard nitrate medium. T-Iso was characterized by its tendency to increase the level of n-3 PUFA with the increase of nitrate, while T.suecica was characterized by no effect of nitrate on the contents of n-3 PUFA of the cells nor a PUFA pattern related to the increase or decrease of nitrate.