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Abstract :
[en] The study aims to isolate microalgal strains from shrimp – farm wastewater and select some of them suitable for production of biomass, biodiesel and other valuable products. We have isolated 4 isolates, namely NL3, NL4, NL6 and NL12. The four isolates were preliminarily identified using molecular techniques based on partial sequence of 18S rRNA gene and classified into four different genera belonging to two phyla, Desmodesmus, Chlorella, Nannochloris (Chlorophyta) and Nannochloropsis (Eustigmatophyta). They were subjected to characterization in terms of growth, protein content, pigment and fatty acid content and profiles. As a result, isolates NL3 and NL6 were chosen for the project. The two strains were further identified based on the whole sequence of 18S rDNA – ITS1-5.8S-ITS2. Isolate NL3 was identified as Desmodesmus sp. NL3, which is proposed to be a new species with two group I introns (S516 and S1046) while isolate nl6 was 100% identical to Nannochloropsis salina (D12, accession number JX185299.1) from Shandong in China, so named Nannochloropsis salina NL6. Those two strains were further characterized in terms of growth, protein, pigment, fatty acid profiles and salinity tolerance (10‰, 20‰, 30‰ and 35‰). The two strains are tolerant to the different salinities studied. Nannochloropsis salina NL6 was characterized by a high percentage of fatty acids (40% DW at the end of exponential phase) and a fatty acid profile suitable for biodiesel production. Desmodesmus sp. NL3 was characterized by high protein (40% DW), biomass (1.54 g/L), and lutein (7 mg/g DW) contents at the end of the exponential phase. Notably, Nannochloropsis salina NL6 (N. salina NL6) was able to produce eicosapentaenoic acid (EPA) and astaxanthin. Their performance on the production of these compounds did not change much across the four salinities. The two strains, therefore, fit the project goals.
