Carbon source utilization and toxin tolerance of oleaginous yeasts

There have been many reports of utilization of oleaginous (lipid accumulating) yeasts for conversion of lignocellulosic hydrolysates to lipids. Seventeen new oleaginous yeast species have been reported from our lab in the last two years. Of over 60 known oleaginous yeast species, some may be more suited to specific hydrolysates than others. Many characteristics contribute to the industrial robustness of an oleaginous yeast strain: fast growth, high yield, production of the desired products, ease of genetic manipulation, ability to utilize certain nutrients, ability to grow independently of costly nutrients such as vitamins, and ability to tolerate stresses such as pH, osmolarity, temperature and toxins. Some combination of these characteristics may already be present in wild precursor strains. In this study, 47 oleaginous yeast strains representing 44 yeast species were tested for ability to utilize carbon sources associated with lignocellulosic hydrolysates, tolerate toxins, and grow in medium without supplemented vitamins. Differences in characteristics such as toxin tolerance were detected when multiple strains of the same species were compared. Some oleaginous yeasts that have not been frequently utilized in research or industrial production emerged as promising candidates for industrial use. No strains were able to utilize all carbon sources and tolerate all toxins tested, which reinforces the importance of comparing multiple strains of multiple species before selecting the most promising candidates for strain and process development. See the companion poster (Sitepu et al.) regarding lipid production by selected yeasts on AFEX^TM–pretreated corn stover hydrolysate.