First records of members of the genus Coelastrella (Chlorophyta) in tundra soils of Duvanny Yar (Sakha Republic, Russia)

Abstract

The present study provides the results of morphological, molecular genetic, and biochemical analyses of six strains of green microalgae belonging to the genus Coelastrella, isolated from tundra soils of Duvanny Yar, a key reference section of Upper Pleistocene deposits on the right bank of the Kolyma River in the Nizhnekolymsky District of the Republic of Sakha (Russia). Strains were identified using light microscopy and molecular phylogenetic analysis based on internal transcribed spacer ITS2 sequences. Three strains, D2_3c1, D4_8k, and D7_11k, were identified as C. affinis; two strains, D2_6a2 and D4_1/5, –as C. polaris; and one strain, D4_4/5, –as C. multistriata. These findings represent the first documented evidence of the presence of these three species in modern soils of Duvanny Yar. Fatty acid profile analysis revealed that α-linolenic acid dominated in all studied strains, with its concentrations ranging from 35% to 42% of the total fatty acid pool. The highest values were recorded in C. polaris strains (40.4–42.1%). C. polaris and C. affinis strains also exhibited high concentrtions of palmitic (20–23%) and linoleic (9–12%) acids. Strain C. multistriata D4_4/5 showed significant accumulation of 7,10,13-hexadecatrienoic acid (16%), the concentration of which was 1.6–3.3 times higher than in the other studied strains. The obtained results expand our understanding of the species diversity of the genus Coelastrella in Arctic ecosystems and demonstrate the significant biotechnological potential of the isolated strains as producers of polyunsaturated fatty acids for applications in aquaculture and the food industry.