Comparative physiology of forty-five Yarrowia lipolytica strains grown on pretreated switchgrass hydrolysate

Yarrowia lipolytica is a well-characterized yeast of the phylum Ascomycota with established use in the biotechnology industry for production of organic acids and enzymes.  In addition, the yeast is a model oleaginous organism that accumulates lipids during growth on a variety of carbon sources.  The availability of an annotated genome, efficient transformation methods, and genetic tools, such as specialized expression vectors and selectable markers, has facilitated metabolic engineering of Y. lipolytica for overproduction of single-cell oil and synthesis of other oleochemicals.  In the present study, we investigated growth and lipid production by forty-five Y. lipolytica strains from the ARS and CBS culture collections on acid-pretreated switchgrass hydrolysate.  The goal of the screening was to identify oleaginous strains of the genetically tractable species that are most suitable for accumulating lipids using abundant, low-cost biomass feedstocks.  Although two recent peer-reviewed studies have reported lipid production by Y. lipolytica on lignocellulosic biomass hydrolysates, they each included only the most commonly used isolate.  In this study, forty-five strains were evaluated  using the same hydrolysate and culture conditions, and we were able to rank the strains in terms of lipid titer and productivity, cell growth, and glucose and xylose utilization.  Lipid production varied considerably among the set (min = 0.06 g/L; max = 5.10 g/L; mean = 2.29 g/L), and three strains were especially promising for cellulosic biomass conversion with average improvements of 43%, 57%, and 64% in final lipid titer as compared to the control strain W29.