Desmids (Zygnematophyceae, Streptophyta) as a promising freshwater microalgal group for the fatty acid production: results of a screening study

This study aimed to investigate fatty acid content and productivity of the insufficiently investigated group of freshwater microalgae-desmids (Zygnematophyceae, Streptophyta)-and to estimate their commercial potential. A total of 29 desmid strains of various environmental preferences were grown in standard cultivation conditions to assess fatty acid concentration and composition and biomass productivity during the growth phases. Six desmid strains belonging to Cosmarium crenatum var. boldtianum, C. meneghinii, C. regnellii var. pseudoregnellii, C. leave, Staurastrum boreale, and S. punctulatum had distinctly high total fatty acid contents (>200 mg g(-1) dry weight), among which C. crenatum had by far the highest average of total fatty acids (308.1 mg g(-1) dry weight). Despite that desmids were grown in a medium which was not enriched with nutrients and CO2, these six strains achieved moderate biomass productivity (up to 0.14 g dry weight L-1 day(-1)), while the fatty acid productivity was in the range 8-11.1 mg L-1 day(-1). The relatively high amounts of linoleic and palmitic acids in C. crenatum var. boldtianum and C. meneghinii were comparable to those found in several commercially grown plants, indicating that fatty acid extracts of these desmids could be utilized in cosmetics, pharmacy, medicine, or in additional industrial applications. On the other hand, the high proportion of oleic acid in a new isolate of Staurastrum boreale, along with its relatively high biomass productivity and cell size, pointed that this strain might be used for further investigations regarding biodiesel production.