Biodiesel Production from Oleaginous Yeast
This study explored a strategy to convert agricultural residues into microbial lipid, which could be further transformed into biodiesel. Demand of alternative fuels is increasing day by day due to the present crisis of petroleum based fuels. Biodiesel is one of the most demanding alternative fuels. One probable solution is to use microorganisms especially oleaginous species, because of their higher lipid content and almost similar composition as plant animal lipid. For this experiment, yeast was selected because of several reasons like easy availability, rapid growth rate, and higher lipid accumulation capacity, capable to grow on a variety of media etc. Among the 250 yeast strains screened for xylose assimilating capacity, eight oleaginous yeasts were selected by Sudan Black B test. The lipid content of these 8 strains was determined by soxhlet extraction method. The optimal fermentation conditions were obtained as follows glucose as carbon source 100 g l yeast extract and peptone as nitrogen sources at, respectively, 8 and 3 g l initial pH of 5.0 Inoculation volume of 5 temperature at 28°C, shaking speed of 180 r min, cultivated for 96 h. More encouraging results were observed for the lipid production with alternative carbon sources. In this experiment, yeast was adapted to accumulate maximum quantity of lipids by providing metabolic stress condition, which was later converted into biodiesel by acid transesterification. Elimination of lipid extraction step has made the process much faster and easier as compared to traditional methods. Presence of fatty acid methyl esters were confirmed by high performance thin layer chromatography HPTLC and gas chromatography GC . Fatty acids composition was determined by gas chromatography GC by comparing with standards.
Oleaginous yeast, Economic production of biodiesel, Yeast biomass, Single step transesterification method.
S. Karthika | M. Kannahi