Alternative culture medium for Nannochloropsis oculata mass culture

Microalgae of the genus Nannochloropsis are highly valued in aquaculture due to their protein, fatty acid, and carotenoid content, offering potential as additives or substitutes for fish meal or oil. However, large-scale production encounters challenges, particularly concerning the culture medium. Thus, this study aimed to assess the impact of substituting artificial sea salt with common salt and standard medium with agricultural fertilizer in Nannochloropsis oculata production. Initially, the effects of reduced salinity were evaluated at salinities of 30, 10, 5, and 1 ups, followed by an examination of the effects of replacing artificial sea salt with common salt and using agricultural fertilizer on microalgae growth. Salinities of 30 and 10 exhibited the highest growth parameters. The salt source had no significant impact on culture growth, while the agricultural fertilizer enhanced it. Common salt increased the concentration of eicosapentaenoic acid compared to artificial sea salt, although the total lipid concentration was higher in microalgae cultured with artificial sea salt. The developed medium was validated through semi-continuous cultures in 100 L flat vertical bags, showing to be an economically viable alternative without hindering N. oculata growth.