Assessing the Potential of Some Freshwater and Saline Microalgae as Biodiesel Feedstock

Abstract

Microalgae have attracted a major interest in biofuel, food and feed stock sectors as they can accumulate lipids, proteins and carbohydrates in large amounts within short periods of time. The selection of the most suitable algal species for biofuel production is based on key parameters such as lipids, fatty acids composition and characteristics. This paper describes the bioprospecting and molecular screening of 21 microalgal strains isolated from different fresh and saline water habitats by analysing their biomass, lipids and fatty acid profiles, used for estimating biodiesel properties. Biomass productivity amongst the strains varied from 142.5±13.4 to 622.8±14.0 mg/L. Seven strains viz. Acutodesmus sp. TST2, Scenedesmus sp. PK1, Desmodesmus armatus TTT1, Desmodesmus armatus FW005, Neochloris sp. RP2, Stichococcus bacillaris LU1 and Hegewaldia sp. LC1 showed a lipid mass fraction of >25% on a dry basis. Fatty acid profiling showed that fatty acids with carbon chain length of C16–C18 such as palmitic, oleic and linoleic acids were major fatty acids in all the isolated species. Three strains viz. Acutodesmus sp. TST2, Stichococcus bacillaris LU1 and Hegewaldia sp. LC1 accumulated high lipid content (>28% dwt), with higher levels of fatty acid profiles of C16–C18 (>70%) indicating their potential as sources of biodiesel with suitable biodiesel properties of high cetane number (57–59), low viscosity (4.73–4.85 mm2/s), lower iodine value (54.4–68.5 gl2/100 g), relative cloud point 9–13 °C) and negative cold filter plugging point (–2 to –6 °C) in accordance with international standards.