Selecting low-cost carbon sources for carotenoid and lipid production by the pink yeast Rhodosporidium toruloides NCYC 921 using flow cytometry

•Carop pulp syrup (CPS) and sugarcane molasses (SCM) were used as carbon sources.•CPS at 75 g L−1 induced the highest fatty acid and carotenoid productivities.•Flow cytometry detected differences between the cell membrane grown on CPS and SCM.•R. toruloides growth on CPS induced lower ratio of permeabilised cells than on SCM.

The present work studied low-cost carbon sources for carotenoid and lipid production using the yeast Rhodosporidum toruloides NCYC 921. Carob pulp syrup and sugarcane molasses at different concentrations were used as low-cost carbon sources in R. toruloides batch cultivations. Carob pulp syrup containing a total sugar concentration of 75 g L−1 induced the highest total fatty acid productivity (1.90 g L−1 h−1) and the highest carotenoid productivity (9.79 μg L−1 h−1). Flow cytometric analysis revealed that most of the yeast cells (>60%) grown on carob pulp syrup displayed intact polarised membranes, conversely to the cells grown on sugarcane molasses, wherein a large proportion (>45%) displayed permeabilised cytoplasmic membranes.