Production of galactitol from galactose by the oleaginous yeast Rhodosporidium toruloides IFO0880

Abstract

AbstractBackgroundSugar alcohols are commonly used as low-calorie sweeteners and can serve as potential building blocks for bio-based chemicals. Previous work has shown that the oleaginous yeastRhodosporidium toruloidesIFO0880 can natively produce arabitol from xylose at relatively high titers, suggesting that it may be a useful host for sugar alcohol production. In this work, we explored whetherR. toruloidescan produce additional sugar alcohols.ResultsRhodosporidium toruloidesis able to produce galactitol from galactose. During growth in nitrogen-rich medium,R. toruloidesproduced 3.2 ± 0.6 g/L, and 8.4 ± 0.8 g/L galactitol from 20 to 40 g/L galactose, respectively. In addition,R. toruloideswas able to produce galactitol from galactose at reduced titers during growth in nitrogen-poor medium, which also induces lipid production. These results suggest thatR. toruloidescan potentially be used for the co-production of lipids and galactitol from galactose. We further characterized the mechanism for galactitol production, including identifying and biochemically characterizing the critical aldose reductase. Intracellular metabolite analysis was also performed to further understand galactose metabolism.ConclusionsRhodosporidium toruloideshas traditionally been used for the production of lipids and lipid-based chemicals. Our work demonstrates thatR. toruloidescan also produce galactitol, which can be used to produce polymers with applications in medicine and as a precursor for anti-cancer drugs. Collectively, our results further establish thatR. toruloidescan produce multiple value-added chemicals from a wide range of sugars.