The Potential of a Brown Microalga Cultivated in High Salt Medium for the Production of High-Value Compounds

Abstract

<i>Amphora</i> sp. was isolated from the Sfax Solar Saltern and cultivated under hypersaline conditions. It contains moderate rates of proteins, lipids, sugars, and minerals and a prominent content of bioactive compounds: polyphenols, chlorophyll a, carotenoids, and fatty acids. The analysis of fatty acids with GC/MS showed that the C16 series accounted for about 75% of <i>Amphora</i> sp. lipids. Saturated fatty acids whose palmitic acid was the most important (27.41%) represented 41.31%. <i>Amphora</i> sp. was found to be rich in monounsaturated fatty acids with dominance of palmitoleic acid. It also contains a significant percentage of polyunsaturated fatty acids with a high amount of eicosapentaenoic acid (2.36%). Among the various solvents used, ethanol at 80% extracted the highest amounts of phenols and flavonoids that were 38.27 mg gallic acid equivalent and 17.69 mg catechin equivalent g^-1 of dried extract, respectively. Using various <i>in vitro</i> assays including DPPH and ABTS radicals methods, reducing power assay, and <i>β</i>-carotene bleaching assay, the 80% ethanolic extract showed high antioxidant activity. A strong antibacterial activity was checked against Gram-positive bacteria (<i>Staphylococcus aureus</i> and <i>Micrococcus luteus</i>) and Gram-negative bacteria (<i>Klebsiella pneumoniae</i> and <i>Salmonella enterica</i>). These results are in favor of <i>Amphora</i> sp. valorization in aquaculture and food and pharmaceutical industries.