Studies on development of super-enzymes from marine hyperthermophiles

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In this study, we firstly isolate the useful marine hyperthermohpilic bacteria for genetic engineering, medicine, food science and chemical engineering. Secondly we purify heat and chemical stable enzymes and clone their genes for the development of unknown genetic resources.The results are as follows ;(1)New anaerobic hyperthermophilic archaeon Pyrococcus sp.growing optimally at 100ﾟC was isolated from a shallow marine hydrothermal vent in Tachibana Bay. The gene for DNA polymerase of this archaeon was cloned and expressed in E.coli. The amino acid sequence of this gene was closely relate to that of pol A from P.furiosus.(2)New aerobic thermophilic bacterium Rhodothermus obamensis OKD7 growing optimally at 80ﾟC was isolated from the same station. CO_2 fixiing enzyme (PEPC) was purified and characterized. The allosteric enzyme PEPC was a homotetramer of 400kDa and showed maximum activity at 75ﾟC.The cloned gene of PEPC was expressed in E.coli. A thermostable recombinant PEPC showed similar property of the wild type.(3)A novel aerobic hyperthermophilic archaeon Aeropyrum pernix K1 growing optimally at 90ﾟC was isolated from a costal soltataric vent at Kodakara Island. Strain K1 produced an extracellular metalloprotease with a molecular mass of 52kDa. The optimum temperature for the enzyme was 100ﾟC.The enzyme was extremely thermostable showing half-life of 1.2h at 125ﾟC.