Screening for oily yeasts able to convert hydrolyzates from biomass to biofuels while maintaining industrial process relevance

Authors: Slininger, Patricia - Pat; Dien, Bruce; Quarterman, Joshua; Thompson, Stephanie; Kurtzman, Cletus

Submitted to: Methods in Molecular Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/10/2018
Publication Date: 5/31/2019
Citation: Slininger, P.J., Dien, B.S., Quarterman, J.C., Thompson, S.R., Kurtzman, C.P. 2019. Screening for oily yeasts able to convert hydrolyzates from biomass to biofuels while maintaining industrial process relevance. Methods in Molecular Biology. 1995:249-283. https://doi.org/10.1007/978-1-4939-9484-7_16.
DOI: https://doi.org/10.1007/978-1-4939-9484-7_16

Interpretive Summary: In this research, a battery of new screening tools and protocols for evaluating yeast-based oil production from renewable biomass were developed and described. Based on conservative estimates, about 1.3 billion tons of plant biomass (lignocellulose) could be harvested each year in the U.S. in the form of energy crops, forest and agricultural residues. Using microorganisms called “oily” yeasts, this biomass could be converted to about 30 billion gallons of biodiesel/year, representing over 60% replacement of current annual U.S. diesel consumption. These unique yeasts can accumulate up to 70% of their cell weight as lipids with fatty acid composition similar to vegetable oil. Research has recently intensified to discover new yeast strains able to function more quickly and efficiently to produce high quality oils for use in biodiesel and chemicals. The new tools and protocols developed in our laboratory enable rapid screening of prospective yeast strains and conditions to maximize lipid yield and production rate. Technology advancements gained as a result of the new methods are expected to promote economic feasibility of high quality biodiesel and jet fuels from renewable biomass. Once operational, the biomass to bio-oil industry is expected to reduce our dependence on foreign oil, support the rural economy, and help to preserve the environment.

Technical Abstract: Research has recently intensified to discover new oleaginous yeast strains able to function quickly and efficiently in low cost lignocellulosic hydrolyzates to produce high quality lipids for use in biodiesel and chemicals. Detailed techniques are given here for ranking candidate yeast strains based on conversion of hydrolyzate sugars to lipids and then optimizing cultivation conditions for best performers in a 96-well aerobic micro-cultivation format. A full battery of assays applicable to high throughput of small-volume samples are described for efficiently evaluating cell biomass production, lipid accumulation, fatty acid composition, and sugar utilization. Orignial data is additionally presented on the validation of the micro-technique for GC analysis of lipid composition in yeast since this application involved modification of a previously published assay for microalgae.