Hansenula polymorpha strain NCYC 495 leu1.1 is a yeast capable of fermenting xylose, cellobiose, and glucose to ethanol at high temperatures (45 – 50° C). This particular strain ferments xylose much more efficiently than other strains of H. polymorpha. Hence, it is a promising strain for the simultaneous saccharification and fermentation (SSF) process, which combines enzymatic hydrolysis of pretreated lignocellulose by cellulases and hemicellulases (exhibiting optimal activities around 50° C) with simultaneous fermentation of produced hexoses and pentoses to ethanol in the same vessel. Commercially feasible SSF technology has not been developed yet because of the absence of a robust organism capable of efficient ethanolic fermentation of xylose and other lignocellulosic sugars at high temperatures. Still, ethanol yield from xylose fermented by this strain is rather low and must be improved via metabolic engineering approaches. This work can be efficient and successful only when a complete genomic sequence is available.
Seqeuencing will enable the identification of the limiting steps (bottlenecks) in the fermentation pathway from xylose to ethanol. In addition, H. polymorpha NCYC 495 is also a popular system for basic research, such as studies of growth and degradation of peroxisomes (organelles that metabolize fatty acids and toxins), nitrate assimilation, resistance to heavy metals and oxidative stress, as well as enabling organisms to produce proteins of biotechnological significance. Studies of this organism’s modes of protein and organelle degradation are important for elucidating the mechanisms of severe human diseases (Huntington’s chorea, Alzheimer’s disease, some forms of cancer). Scientists from diverse fields will greatly benefit from a complete genomic sequence database of this organism.
Principal Investigators: Andriy A. Sibirny (Nat. Acad. Sci. of Ukraine and Rzeszów Univ., Poland)
Program: CSP 2009