The use of flow cytometry to assess Rhodosporidium toruloides NCYC 921 performance for lipid production using Miscanthus sp. hydrolysates

The yeast Rhodosporidium toruloides NCYC 921 was used for lipid production, using Miscanthus biomass hydrolysate as carbon source. The hydrolysate was obtained by enzymatic hydrolysis of Miscanthus biomass (at high solids loading) previously subjected to a hydrothermal pre-treatment. Afterwards R. toruloides was grown on Miscanthus sp. hydrolysate (MH), undiluted and diluted, at the ratios of 1:4 (20 % v/v), 1:2 (33.3 % v/v) and 3:1 (75 % v/v). The best yeast performance was observed for MH 1:2 medium dilution, reaching the maximal biomass concentration of 6.3 g/L, the lipid content of 30.67 % w/w dry cell weight and the lipid concentration of 1.64 g/L. Flow cytometry demonstrated that R. toruloides cell membrane was massively damaged when the yeast was grown on undiluted MH, due to the presence of phenolic compounds; however, when the yeast was grown on diluted MH 1:2 and 1:4, the proportion of intact cells has increased during the yeast cultivation.