Using Multi-parameter Flow Cytometry to Monitor the Yeast Rhodotorula glutinis CCMI 145 Batch Growth and Oil Production Towards Biodiesel

Multi-parameter flow cytometry was used to monitor cell intrinsic light scatter, viability, and lipid content of Rhodotorula glutinis CCMI 145 cells grown in shake flasks. Changes in the side light scatter and forward light scatter were detected during the yeast batch growth, which were attributed to the different yeast growth phases. A progressive increase in the proportion of cells stained with PI (cells with permeabilized cytoplasmic membrane) was observed during the yeast growth, attaining 79% at the end of the fermentation. A high correlation between the Nile Red fluorescence intensity measured by flow cytometry and total lipid content assayed by the traditional gravimetric lipid analysis was found for this yeast, making this method a suitable and quick technique for the screening of yeast strains for lipid production and optimization of biofuel production bioprocesses. Medium growth optimization for enhancement of the yeast oil production is now in progress.