Long-term preservation of concentrated Nannochloropsis gaditana cultures for use in aquaculture

The aim of this paper is to solve problems that may arise in microalgae cultivation facilities at a hatchery in such a way that its activities are not disrupted. Thus, the effect of storage conditions (time, initial biomass concentration, presence or absence of light, addition of preservatives and conservation atmospheres) on cell viability, evolution of sample concentration, contamination, fatty acid and pigment content for long-term preservation of Nannochloropsis gaditana biomass has been studied. The polyunsaturated fatty acid content was maintained and the eicosapentaenoic acid (EPA, 20:5n3) content was kept stable at 3.6 % (d.w.). The total pigments content was also preserved at 0.85 % (d.w.), what allowed maintaining the antioxidant activity of samples. The results show that samples preserved both as concentrated inocula ready to run a photobioreactor, at an initial biomass (N. gaditana) concentration of 5 g L-1, and as pastes to be used as live food if any incident happens in a hatchery, at 150 g L-1, can be stored for up to 4 months at 4 A degrees C under nitrogen or air atmosphere of conservation maintaining the cell viability and the sample concentration stable and at low incident irradiance (35 mu mol photons m(-2) s(-1)). This allows the photosynthetic activity of cells to be preserved in the case of samples at 5 g L-1. The bacterial load was kept at low level by the regular addition of preservative agents.