Phylogeny and Fatty Acid Profiles of New Pinnularia (Bacillariophyta) Species from Soils of Vietnam

We studied the morphology, ultrastructure, and phylogeny of eight soil diatom strains assigned to the Pinnularia genus. Six of these strains, identified by us as new species, are described for the first time. We provide a comprehensive comparison with related species and include ecological data. Molecular phylogeny reconstruction using 18S rDNA and rbcL affiliates the new strains with different subclades within Pinnularia, including ‘borealis’, ‘grunowii’ and ‘stomatophora’. We also studied the fatty acid profiles in connection with the emerging biotechnological value of diatoms as a source of lipids. Stearic (36.0–64.4%), palmitic (20.1–30.4%), and palmitoleic (up to 20.8%) acids were the dominant fatty acids in the algae cultured on Waris-H + Si medium. High yields of saturated and monounsaturated fatty acids position the novel Pinnularia strains as a promising feedstock for biofuel production

Antioxidant Status and Biotechnological Potential of New <em>Vischeria vischeri</em> (Eustigmatophyceae) Soil Strains in Enrichment Cultures

The functional state of enrichment cultures of the Eustigmatophycean strains Vischeria vischeri MZ–E3 and MZ–E4 after 25-day cultivation in the BBM medium was studied. The concentrations of chlorophyll a, total carotenoids, protein, vitamins A and E, fatty acid peroxidation product content, an antioxidant enzyme, and succinate dehydrogenase activity were measured. MZ–E3 succinate dehydrogenase activity was significantly higher by 2.21 times; the MZ–E4 strain had 2.94 times higher glutathione peroxidase activity. The MZ–E3 antioxidant activity index and the MZ–E3 unsaturation of fatty acids were 1.3 and 1.25 times higher than the MZ–E4. The retinol and α-tocopherol content of the MZ–E3 was 28.6% and 38.76% higher than MZ–E4. The main fatty acid profile differences were the 3.46-fold and 3.92-fold higher stearic and eicosapentaenoic acid content in the MZ–E4 biomass. MZ–E3 had higher antioxidant, energy, and metabolic and photosynthetic status than MZ–E4. The antioxidant status of the studied strains showed the dependence of the adaptive mechanisms of each, associated with differences in the ecological conditions of the biotopes from which they were isolated. These strains are promising for producing α-tocopherol and biomass enriched with omega-3 and omega-6 fatty acids