Using Aspergillus ochraceus, a Native Fungus, to Convert Biodiesel-Derived Crude Glycerol to Single Cell Oil for Commercial Applications

Microbial oils are becoming increasingly popular as a means of creating alternatives to traditional transportation fuels. From this point of view, the study sought to produce microbial lipids from an industrial residue that is typically regarded as waste in order to reduce the process costs and explore the end applications of the lipids synthesized. For the first time, the ability of Aspergillus ochraceus, a native fungus, to use the undervalued by-product of biodiesel production, glycerol, for the synthesis of microbial lipids was investigated. Glycerol concentration of 80 g/L resulted in maximum biomass and lipid production; concentration exceeding 80 g/L was found to be detrimental to fungal growth. Owing to the maximum production of lipids during the 288th hour of incubation in the medium containing 80 g/L of crude glycerol, day 12 was considered as the ideal time for lipid extraction from the fungus. The optimal process conditions were determined to be a 12% (v/v) inoculum concentration (spore count equal to 10.8* 10(11) spores/mL), pH 6.0 and a temperature of 30 degrees C. The maximum biomass concentration, lipid concentration and lipid content achieved at optimized conditions were 14.16 g/L, 4.97 g/L and 35.1%, respectively. The extracted lipids contained ascorbyl dipalmitate, elaidic acid and stearic acid as major constituents, making them an excellent feedstock for production of valuable lipid metabolites of wide commercial significance and biodiesel. Preliminary investigations further suggested that the study organism was resistant to impurities present in crude glycerol, thus proving it to be a potent host for converting biodegradable waste to value added end products. [GRAPHICS] .

Automated summary

Microbial lipids were successfully synthesized from an industrial residue using Aspergillus ochraceus. The best conditions for lipid production were determined to be a glycerol concentration of 80 g/L, a 12% (v/v) inoculum concentration, pH 6.0, and a temperature of 30 degrees C. The extracted lipids contained valuable constituents for commercial use.