Phycoprospecting the nutraceutical potential of <i>Isochrysis</i> sp as a source of aquafeed and other high‐value products

Abstract

Marine microalgae, an exceptionally diverse yet highly specialized group of photoautotrophs are the key regulators of ecological habitats and aquatic ecosystems. Isochrysis, a ubiquitously present golden-brown flagellate, isolated from southern coastline of India, was assessed as a suitable feed source for aquaculture. Absence of tough cell walls with an appropriate ingestible cell size of 4–5 μm and fast growth rate besides possessing essential nutritive constituents like high per cent of cellular lipids (32% dry weight [DW]) and significant yield of eicosapentaenoic acid (EPA) (10.21 mg g−1 DW) and docosahexaenoic acid (DHA) (7.24 mg g−1 DW) proves this strain as an ideal option for aqua feed. The concomitant synthesis of carotenoids and numerous secondary metabolites also highlighted its incomparable antioxidant capacity (up to 43.4% inhibition of α, α-diphenyl –β-picryl hydrazyl (DPPH) radical) as well as their role as a biocontrol agent in preventing growth of fish pathogens like Aeromonas. This study thereby demonstrates the potential utilization of Isochrysis as a quintessential dietary supplement, and fish feed as a sustainable feedstock.