BIOPROSPECTION, ISOLATION AND USE IN AQUACULTURE OF NEW MICROALGA STRAIN Tetraselmis sp. IMP3

In the last decades, microalgae , have attracted attention as  a  possible feedstock for many applications. Since  it contains various compounds , thorough assessments of microalgae biomass are essential to determine whet her it should be applied to aquaculture or  to  other areas,  such as pharmaceuticals or food industry. IPMA , within the  scope of ALGARED+ project, realized the importance of bioprospecting new taxas, to increase the knowledge base ,  and  to develop a protocol to collect and isolate microalgae from high yielding sites such as fish pounds.  For this purpose, samples were collected from EPPO facilities and isolated by fluorescence activated cell sorting (FACS) using a pre-enrichment step, BODIPY staining. After culture, samples were taken for genetic identification. To understand their feasibility for aquaculture, all the isolated species were grown in aquaculture maternity conditions, plastic bag photobioreactors, with the most common culture mediums (MAM, f2 and Phytobloom) , and  the strains that didn't grown properly were discarded.   As a result, the promising strain Tetraselmis sp. IMP3 (Chlorophyta, Chlorodendrophyceae) was isolated.  IPM3 demonstrated a high resilience and capacity to grow in seawa ter  liquid and solid growth medium at different medium compositions. Liquid culture was carried in varying photoperiods, to study the relationship of light  and growth performance, number of cell and dry weight with the same light intensity (150 photons. s^-1. m^-2) . Samples were collected, during the stationary phase, for fatty acid profile assessment, to evaluate the potential use in food chain during fish larvae cultivation. Results showed that IMP3 contain relatively high levels of polyunsatur ated fatty acids (PUFA) and,  among these, ω3 PUFA were the most abundant. Howe ver, highly unsaturated ω3 FA contents were relatively low. In general, eicosapentaenoic acid (EPA, 20:5 ω3) contents were low. Conversely, docosahexaenoic acid (DHA, 2 2:6 ω3) never exceeded 3 % of total FA. α-Linolenic acid (ALA, 18:3 ω3) were the main PUFA. High con tents of palmitic (16:0) and ol eic (18:1 ω9 ) acids were found in Tetraselmis  sp. IMP3.

The enrichment of Rotifers spp. and Artemia sp. was performed, during 12 and 24 hours, to evaluate the utility of that strain to be bioencapsulated by zooplankton.  Results indicate  that  both organisms can graze on Tetraselmis sp. IMP3 (Table I) profiting from an increase of the survival rate (100%). This strain can be also used directly as feed marine fish larvae (e. g. sardines).

This s tudy had the support of the project  ALGARED+ (INTERREG VA (POCTEP), ID:1398).