초록
The hyperthermophilic archaeon, Pyrococcus furiosus, grows optimally near 100<SUP>o</SUP>C by fermenting sugars to acetate, carbon dioxide and molecular hydrogen as the major end products. The organism has recently been exploited to produce biofuels using a temperature-dependent metabolic switch using genes from microorganisms that grow near 70<SUP>o</SUP>C. However, little is known about its metabolism at the lower temperatures. We show here that P. furiosus produces acetoin (3-hydroxybutanone) as a major product at temperatures below 80<SUP>o</SUP>C. A novel type of acetolactate synthase (ALS), which is involved in branched-chain amino acid biosynthesis, is responsible and deletion of the als gene abolishes acetoin production. Accordingly, deletion of als in a strain of P. furiosus containing a novel pathway for ethanol production significantly improved the yield of ethanol. These results also demonstrate that P. furiosus is a potential platform for the biological production of acetoin at temperatures in the 70-80<SUP>o</SUP>C range.