Using non-ionic surfactant as an accelerator to increase extracellular lipid production by oleaginous yeast Cryptococcus curvatus MUCL 29819

The aim of this work was to study the effects of non-ionic surfactant on the accumulation of total microbial lipids and extracellular lipid by Cryptococcus curvatus MUCL 29819 with acetic acid as carbon source. Compared with Brij 58 and Triton X-100, Brij 58 most increased the total lipids, with a yield up to 2.84 g/L (extracellular lipid up to 47%). Brij 58 also increased the metabolic flow of acetic acid to lipid accumulation (maximum conversion of 0.54 g/g at 1.0 g/L Brij 58) and limited its conversion to non-lipid biomass (minimum conversion 0.12 g/g at 0.5 g/L Brij 58). The improvement in the proportion of extracellular lipid by tea saponin and Brij 58 was due to changes in cell membrane permeability and improvement of cell membrane fluidity. Triton X-100, having weaker surface activity, promoted release of extracellular lipid and also increased the proportion of polyunsaturated fatty acid (C22:6, docosahexaenoic acid).