Production of ethanol from L-arabinose by Saccharomyces cerevisiae containing a fungal L-arabinose pathway

The fungal pathway for L-arabinose catabolism converts c-arabinose to D-xylulose 5-phosphate in five steps. The intermediates are, in this order: L-arabinitol, L-xylulose, xylitol and D-xylulose. Only some of the genes for the corresponding enzymes were known. We have recently identified the two missing genes for L-arabinitol 4-dehydrogenase and L-xylulose reductase and shown that overexpression of all the genes of the pathway in Saccharomyces cerevisiae enables growth on L-arabinose. Under anaerobic conditions ethanol is produced from L-arabinose, but at a very low rate. The reasons for the low rate of L-arabinose fermentation are discussed. (C) 2002 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.