High-Efficiency Ukrainian Strains of Microalgae for Biodiesel Fuel Production (Overview)

In Ukraine, the research works focused on the study of green microalgae as an alternative source of feedstock for biodiesel production started in 2009. The screening of the Ukrainian Microalgae Culture Collection (IBASU-A) revealed a number of promising strains of species belonging to Chlorella, Chloroidium, Desmodesmus, and Parachlorella (Chlorellaceae and Scenedesmaceae) genera. The main criteria for strain selection were: accumulation of a significant volume of lipids, high kinetic characteristics (specific growth rate and productivity), resistance to stresses and biological contaminations. Some novel algal strains with relevant properties and optimized to the local climatic conditions were also isolated from different regions of Ukraine. Biotechnological studies showed a rather high potential of many of them, especially those of species from Tetradesmus and Desmodesmus (Scenedesmaceae) genera. Recently, some strains of species belonging to Monoraphidium, Raphidocelis, and Selenastrum (Selenastraceae) genera have also been isolated and the search for strains with a high biomass production continued.

Moving from an overview of the oleaginous high-efficiency strains present in the largest algal collection in Ukraine (IBASU-A) and a critical analysis of problems related to biodiesel fuel production by microalgae, here we report preliminary data on biomass productivity, lipid amount and fatty acid profiles of some Ukrainian strains of Selenastraceae family.

Traditional techniques were used for the isolation of new strains. The study of growth characteristics was carried out under intensive conditions and the daily increase of algal biomass was determined by the gravimetrical method. The data obtained on growth characteristics were compared with those of the well-known producers of biomass. The fatty acid composition in the most promising strains was determined by the gas-liquid chromatography.

Three new algal strains, M. minutum IBASU-A 574, Monoraphidium sp. IBASU-A 377 and Raphidocelis subcapitata IBASU-A 358, of Selenastraceae, adapted to regional climatic conditions, were isolated from different regions of Ukraine. They showed a higher efficiency in biodiesel production with respect to strains of Chlorellaceae and Scenedesmaceae earlier investigated. The biomass productivity of M. minutum IBASU-A 574, Monoraphidium sp. IBASU-A 377 and Raphidocelis subcapitata IBASU-A 358 was 1.84, 0.84 and 1.32 g DW L^-1·day^-1, while the lipid contents were 33.65%, 29.43% and 23.14%, respectively. Their fatty acid profiles included mainly C16:0, C18:2 and C18:3, all of interest for biodiesel production.

The Ukrainian Microalgae Culture Collection has been supplemented with strains of species from family Selenastraceae showing high-efficiency for biodiesel production and adaptation to local environmental conditions.