Evaluation of lipid accumulation from lignocellulosic sugars by Mortierella isabellina for biodiesel production

Abstract

The filamentous fungus Mortierella isabellina ATCC42613 was used to assess the conversion of different carbon sources (glucose, xylose, mixed glucose/xylose, acid and alkali treated corn stover hydrolysate) in submerged media to lipid. Glucose and xylose cultures composed of varying initial sugar concentrations (28.1-91.7gL(-1), and 26.6-90.9gL(-1) respectively) showed a positive correlation to lipid accumulation, with significant quantities occurring at the upper limit of the substrate range (10.2, and 8.8gL(-1) lipid respectively). While lipid concentrations increased with each incremental glucose and xylose level, the lipid yield (0.41-0.44, and 0.39-0.43gg(-1) cell mass respectively), and intracellular fatty acid composition remained relatively constant. Additionally, sulfuric acid hydrolysate, without detoxification, exhibited greater cell mass, and equivalent lipid production compared to synthetic medium with similar initial glucose and xylose concentrations. These results elucidate the potential of utilizing filamentous fungal fermentation to accumulate lipids from lignocellulosic biomass for biodiesel production.