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.