Microbial Physiology of Alcohol and Hydrogen Production at High Temperatures

超嗜热菌是一组在80°C及以上条件下生长最佳的微生物。其中一些可以发酵各种生物质来生产酒精和氢气，这是可再生能源。由于它们在高温下在液相中的溶解度较低，在线收集乙醇或丁醇与使用酵母的传统发酵过程中使用蒸馏步骤相比是有利的。此外，也不需要冷却，这是大多数大规模发酵过程所需要的一个重要的能量消耗过程。超嗜热菌还具有新的耐热酶，具有很高的催化效率。因此，本研究的长期目标是分离新的和高产醇和产氢的超嗜热微生物，表征新的耐热酶，如醇脱氢酶、醛生产酶和氢化酶，揭示它们在代谢途径中的作用以及在生产醇和氢作为生物燃料方面的潜在应用。关键酶将从新分离的物种和已经从细菌（Thermotoga hypogea, Tmax=90°C和Thermotoga maritima， Tmax=90°C）和古细菌（Thermococcus guaymasensis, Tmax=90°C和Hyperthermus butylicus， Tmax= 112°C）中获得的具有代表性的嗜热菌中纯化和表征。这项工作的成功完成将导致构建在更高温度下生产酒精和氢气的替代和更有效的系统，并发现用于生物技术应用的新型生物催化剂。

Hyperthermophiles are a group of microorganisms growing optimally at 80°C and above. Some of them can ferment various kinds of biomass to produce alcohol and hydrogen, renewable energy sources. Due to their lower solubility in liquid phase at high temperatures, on-line collection of ethanol or butanol is advantageous compared to the use of a distillation step in a conventional fermentation process using yeast. Also, there would be no need for cooling, a significant energy consuming procedure required for most large-scale fermentation process. Hyperthermophiles also possess new thermostable enzymes that have great catalytic efficiency. Therefore, the long-term goal of the research described in this proposal is to isolate new and high alcohol- and hydrogen-producing hyperthermophilic microorganisms, characterize novel thermostable enzymes such as alcohol dehydrogenases, aldehyde-producing enzymes and hydrogenases, and reveal their roles in metabolic pathways and potential applications in the production of alcohols and hydrogen as biofuels. Key enzymes will be purified and characterized from newly isolated species and the representative hyperthermophiles already available from Bacteria (Thermotoga hypogea, Tmax=90°C and Thermotoga maritima, Tmax=90°C) and Archaea (Thermococcus guaymasensis, Tmax = 90°C and Hyperthermus butylicus, Tmax =112°C). Successful completion of this work will lead towards the construction of alternative and more efficient systems for the production of alcohol and hydrogen at higher temperatures, and the discovery of novel biocatalysts for applications in biotechnology.