Fatty acid profiling of new Irish microalgal isolates producing the high-value metabolites EPA and DHA

Microalgae constitute a heterogeneous and diverse group of organisms capable of accumulating high-value products under specific conditions, making them promising organisms for biotechnological applications in the nutraceutical, functional food, animal feed, biofertilisation or biofuel sectors. Recent studies have shown that most regions of the world display low to very low levels of nutritional intakes of the long chain polyunsaturated omega-3 fatty acids EPA and DHA, highlighting the requirement for economically and environmentally sustainable means of raising the nutritional quality of foods and feeds. Eighty-five microalgae strains isolated from aquatic habitats in Ireland were successfully brought into culture and phototrophically grown, which was assessed for fatty acid composition using GC/MS. Hierarchical clustering grouped the strains into five assemblages based on their fatty acid profiles. Three marine strains (diatom cf. Stauroneis sp. LACW24, ochrophyte cf. Phaeothamnion sp. LACW34 and haptophyte Diacronema sp. GMC30) which could synthesise EPA and/or DHA were further studied in 15 L reactors to ascertain variation in their fatty acid profiles over a 65-day cultivation regime. The average yields of EPA were 3.9, 11.9 and 1.3 mg EPA / g DW for GMC30, LACW24 and LACW34, respectively. The average yields of DHA were 3.0 and 2.0 mg DHA / g DW for GMC30 and LACW34, respectively. The capacity of the strains to produce EPA and/or DHA, together with the fact that they have been previously shown to exhibit antioxidant activity and to contain appreciable levels of carotenoid pigments, make them potential candidates for the biorefining of high-value metabolites.