초록
<P><B>Abstract</B></P><P>Conversion of byproduct from biodiesel production glycerol to high‐value compounds is of great importance. Ethanol is considered a promising product of glycerol bioconversion. The methylotrophic thermotolerant yeast <I>Ogataea</I> (<I>Hansenula</I>) <I>polymorpha</I> is of great interest for this purpose as the glycerol byproduct contains methanol and heavy metals as contaminants, and this yeast utilizes methanol and is relatively resistant to heavy metals. Besides, <I>O. polymorpha</I> shows robust growth on glycerol and produces ethanol from various carbon sources. The thermotolerance of this yeast is an additional advantage, allowing increased fermentation temperature to 45–48 °C, leading to increased rate of the fermentation process and a fall in the cost of distillation. The wild‐type strain of <I>O. polymorpha</I> produces insignificant amounts of ethanol from glycerol (0.8 g/l). Overexpression of <I>PDC1</I> coding for pyruvate decarboxylase enhanced ethanol production up to 3.1 g/l, whereas simultaneous overexpression of <I>PDC1</I> and <I>ADH1</I> (coding for alcohol dehydrogenase) led to further increase in ethanol production from glycerol. Moreover, the increased temperature of fermentation up to 45 °C stimulated the production of ethanol from glycerol used as the only carbon source up to 5.0 g/l, which exceeds the data obtained by methylotrophic yeast strains reported so far. Copyright © 2016 John Wiley & Sons, Ltd.</P>