Cultivation of oleaginous yeast using aqueous fractions derived from hydrothermal pretreatments of biomass

•Waste glycerol from hydrolysis of fats and oils was used for growing oleaginous yeast.•Growth and lipid accumulation occurred at levels identical to commercial pure glycerol.•Byproduct of hydrothermally processed C. curvatus was recycled for yeast growth.•Recycling promoted higher biomass production without affecting lipid accumulation.

This study addresses some of the current challenges in producing biofuels from yeast oils. Specifically, it valorizes byproduct waste streams of biomass processing technologies by integrating them as alternative carbon or nutrient sources in oleaginous yeast cultivation. Crude glycerol recovered from the thermal hydrolysis of various fats and oils was successfully used in culturing of the oleaginous yeast Cryptococcus curvatus, with growth and lipid accumulation occurring at levels identical to those achieved when commercially purchased glycerol was used. The aqueous byproduct stream from the hydrothermal processing of C. curvatus can also be recycled as a growth substrate for subsequent C. curvatus cultures. The addition of this stream promoted higher biomass production without affecting lipid accumulation and only moderately changing the fatty acid profile. Use of these recycling strategies reduces costs and environmental impact of current microbial biofuels production by providing accessible, non-expensive carbon sources and nutrients for oleaginous yeast cultivation.