Recovery of Fuel-Precursor Lipids from Oleaginous Yeast

Mary Biddy, Jacob Kruger, Nicholas Cleveland, Tao Dong, Kelsey Kinley, Nicholas Nagle, Gregg Beckham, James McMillan, Andrew Lowell

Research output: Contribution to journalArticlepeer-review

30 Scopus Citations


Bioderived lipids offer a potentially promising intermediate to displace petroleum-derived diesel. One of the key challenges for the production of lipids via microbial cell mass is that these products are stored intracellularly and must be extracted and recovered efficiently and economically. Thus, improved methods of cell lysis and lipid extraction are needed. In this study, we examine lipid extraction from wet oleaginous yeast in combination with seven different cell lysis approaches encompassing both physical and chemical techniques (high-pressure homogenization, microwave and conventional thermal treatments, bead beating, acid, base, and enzymatic treatments) to facilitate lipid extraction from a model oleaginous yeast strain, Lipomyces starkeyi. Of the seven techniques investigated, acid treatment led to the highest lipid recovery yields. Further exploration of acid treatment and integration with an economic model revealed that treatment at 170 °C for 60 min at 1 wt % H2SO4 and 8 wt % yeast solids represents a viable option for both lipid recovery yield and process economics, enabling experimental lipid recovery yields of 88.5-93.0% to be achieved at a corresponding estimated minimum fuel selling price (MFSP) of 5.13-5.61/gallon of gasoline equivalent (GGE). The same acid treatment conditions applied to two other strains of oleaginous yeast (Cutaneotrichosporon curvatus and Rhodotorula toruloides) resulted in similar lipid recovery yields. In pretreatment experiments scaled up to 300 mL, slightly lower temperatures or shorter pretreatment times, along with higher yeast solids loading, resulted in higher lipid yields than the conditions identified from the small-scale runs. Two replicate runs carried out at 170 °C for 30 min using 1 wt % H2SO4 and 19 wt % yeast solids achieved an average lipid recovery of 96.1% at a corresponding estimated MFSP of 4.89/GGE. In all cases, the lipids are primarily triglycerides and free fatty acids comprised mainly of palmitic, stearic, and oleic acids, with smaller fractions of polar lipids. The fatty acid composition of the lipids extracted from the wet treated cell mass is the same as that in freeze-dried whole oleaginous yeast cell mass, suggesting the acid treatment renders all lipids extractable. This work demonstrates that acid treatment is a robust and effective cell lysis technique in a microbial lipid-based biofuel scenario and provides a baseline for further scale-up and process integration.

Original languageAmerican English
Pages (from-to)2921-2931
Number of pages11
JournalACS Sustainable Chemistry and Engineering
Issue number3
StatePublished - 5 Mar 2018

Bibliographical note

Publisher Copyright:
© 2018 American Chemical Society.

NREL Publication Number

  • NREL/JA-5100-70832


  • Acid pretreatment
  • Cell lysis
  • Lipid extraction
  • Oleaginous yeast
  • Single-cell oil


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