[Metabolic engineering of yeast Hansenula polymorpha for construction of efficient ethanol producers]

Until recently, the methylotrophic yeast was not considered as a potential producer of biofuels, particularly of ethanol from lignocellulosic hydrolysates. The first work published 10 years ago reveals the ability of thermotolerant methylotrophic yeast Hansenula polymorpha to ferment xylose--one of the main sugars of lignocellulosic hydrolysates, which has made these yeast promising organism for high temperature alcoholic fermentation. Such feature of the H. polymorpha can be used in the implementation of potentially effective process of simultaneous saccharification and fermentation (SSF) of raw materials. SSF allows combining enzymatic hydrolysis of raw materials with the conversion of produced sugars into ethanol: enzymes hydrolyze polysaccharides to monomers, which are immediately consumed by microorganisms-producers of ethanol. However, the efficiency of alcoholic fermentation of major sugars realized after hydrolysis of lignocellulosic raw materials, and especially xylose, by wild strains of H. polymorpha requires significant improvement. In this review the main results of metabolic engineering of H. polymorpha for the construction of improved producers of ethanol from xylose, starch, xylan, and glycerol, as well as strains with increased tolerance to high temperature and ethanol are represented.