Isolation of diatom Navicula cryptocephala and characterization of oil extracted for biodiesel production

Abstract

Over the past decade diatoms are screened for high lipid content. Geologists claim that much of crude oil comes from diatoms. In this study diatom Navicula cryptocephala, isolated from fresh water source was grown on suitable media for extracting and characterizing the oil for biodiesel production. Three methods namely, shake flask, polythene bag and photobioreactor were adopted for culturing the diatom. The maximum yield of biomass was obtained in photobioreactor (5.95 g/ 100 ml of media). Compound microscope and electron microscopic studies were carried out to identify the diatom. Both soxhlet and sonication methods were used for extraction of oil from the diatom biomass. The yield of oil is higher in sonication method (0.364 g/g of dry biomass). Further characterization of oil using gas chromatography showed the presence of Palmitic acid, Oleic acid, Palmitolic acid and linoleic acid as major fatty acids. HPLC analysis of crude oil showed the presence of OLL (dilinoleoyloleoylglycerol) and OOL (linoleoyldioleoylglycerol) as major triacylglycerols (TAGs).

Key words: Diatom, biodiesel, triaclyglycerols, photobioreactor.