Alcohol and hydrogen metabolism of hyperthermophilic microorganisms

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The long-term goal of the proposed research is to characterize novel thermostable alcohol dehydrogenases and hydrogenases, and to reveal their roles and potential applications as key enzymes for the production of alcohol and hydrogen as biofuels. Hyperthermophiles have a remarkable property of growing at temperatures of 90°C and above, and they are capable of metabolizing carbohydrates including various biopolymers and some waste materials to produce ethanol and hydrogen. However, there is very limited knowledge about all the enzymes and their metabolic regulation as well as metabolic pathways involved in the hyperthermophilic production of alcohol and hydrogen. One of the objectives of the research is to investigate the mechanisms of alcohol and hydrogen production from carbohydrates including glycerol, a by-product of biodiesel manufacture. The regulation of the production of ethanol and hydrogen will be studied under various growth conditions, and the identification of key enzymes involved in the metabolic pathways will be investigated using two-dimensional gel electrophoresis and biochemical analysis as well as molecular probes. The enzymes will be purified and characterized with respect to their catalytic and biophysical properties using techniques including enzymatic analyses and three-dimensional structural determination. The optimization of the production of alcohol and hydrogen will be achieved using molecular techniques available for hyperthermophiles. The microorganisms to be used in this study include representatives from the domains of Bacteria (Thermotoga maritima, Tmax =90°C, and T. petrophila, Tmax =88°C) and Archaea (Thermococcus guaymasensis, Tmax =90°C, and T. kodakarensis KOD1, Tmax =100°C). Successful completion of this research will provide further information about the hyperthermophilic alcohol and hydrogen metabolism, and elucidate the metabolic pathways at temperatures near 100°C. Furthermore, the results obtained will provide key information in the construction of alternative and more efficient systems for the production of biofuels alcohol and hydrogen, as well as new information on the evolutionary relationships between hyperthermophilic and mesophilic enzymes.