Lipid production in the under-characterized oleaginous yeasts, Rhodosporidium babjevae and Rhodosporidium diobovatum, from biodiesel-derived waste glycerol.

The growth, lipid production, and carbon use efficiency of two oleaginous yeasts, Rhodosporidium babjevae and Rhodosporidium diobovatum, were compared under nitrogen-limiting conditions with glycerol as the carbon source. Final biomass concentrations of R. babjevae and R. diobovatum were 9.4±0.80g/L and 12.0±0.82g/L, respectively, after 120h of growth. Final lipid accumulation in for R. babjevae and R. diobovatum were 34.9±3.0% cell dry weight (cdw) and 63.7±4.5% cdw, respectively. Biomass production increased to 9.9±0.2g/L for R. babjevae and 14.1±0.2g/L for R. diobovatum in medium containing biodiesel-derived waste glycerol, but lipid accumulation decreased in both species. In a 7L bioreactor with biodiesel-derived glycerol as carbon source, R. diobovatum produced 13.6±0.4g/L biomass and accumulated lipids to 50.7±2.2% cdw, matching flask experiments.