초록
<P><B>Significance</B></P><P>The microbial production of ethanol (bioethanol) is a massive commercialized technology. Though alcohols with longer carbon chains are chemically much better suited for current transportation needs, their biotechnological production remains challenging. Here we have engineered the model hyperthermophile <I>Pyrococcus furiosus</I> to produce various alcohols from their corresponding organic acids by constructing a synthetic route termed the AOR/AdhA pathway. Our study is also the first example, to our knowledge, of significant alcohol formation in an archaeon, emphasizing the biotechnological potential of novel microorganisms. Moreover, we show that carbon monoxide and hydrogen (syngas) can be used as the driving forces for alcohol production. The application of the AOR/AdhA pathway in syngas-fermenting microorganisms is potentially a game-changing platform technology for the production of longer bioalcohols.</P><P>Bioethanol production is achieved by only two metabolic pathways and only at moderate temperatures. Herein a fundamentally different synthetic pathway for bioalcohol production at 70 °C was constructed by insertion of the gene for bacterial alcohol dehydrogenase (AdhA) into the archaeon <I>Pyrococcus furiosus</I>. The engineered strain converted glucose to ethanol via acetate and acetaldehyde, catalyzed by the host-encoded aldehyde ferredoxin oxidoreductase (AOR) and heterologously expressed AdhA, in an energy-conserving, redox-balanced pathway. Furthermore, the AOR/AdhA pathway also converted exogenously added aliphatic and aromatic carboxylic acids to the corresponding alcohol using glucose, pyruvate, and/or hydrogen as the source of reductant. By heterologous coexpression of a membrane-bound carbon monoxide dehydrogenase, CO was used as a reductant for converting carboxylic acids to alcohols. Redirecting the fermentative metabolism of <I>P. furiosus</I> through strategic insertion of foreign genes creates unprecedented opportunities for thermophilic bioalcohol production. Moreover, the AOR/AdhA pathway is a potentially game-changing strategy for syngas fermentation, especially in combination with carbon chain elongation pathways.</P>