Methanococcus jannaschii, a deep-sea thermophile: Pressure-temperature effects on the growth and methane production, and purification and characterization of hydrogenases
Methanogenesis and growth at both 86 and 90{degree}C were accelerated by pressure up to 750 atm, but growth was not observed above 90{degree}C at 250 atm. However, growth and methanogenesis were uncoupled above 90{degree}C, and the high-temperature limit for methanogenesis was increased by pressure. Substantial methane formation was evident at 98{degree}C and 250 atm, whereas no methane formation was observed at 94{degree}C and 7.8 atm. The present work is the first report on the purification of two hydrogenases, F{sub 420}-reactive and F{sub 420}-nonreactive, from an extremely thermophillic methanogen. The enzymes were purified using anion-exchange chromatography, salt precipitation, and preparative native PAGE. The major form for both hydrogenases was an aggregate of M{sub r} ca. 510,000. The F{sub 420}-nonreactive enzyme was further resolved into two subunits (M{sub r} 49, 35 K). The pH and temperature optima for the F{sub 420}-nonreactive hydrogenase has no pH optimum for methyl viologen (MV)-reducing activity, and its temperature optimum was 90{degree}C. F{sub 420}-reducing activity, however, was maximal at a pH of 7 and a temperature of 80{degree}C. Both enzymes were active up to about 103{degree}C with MV as an electron acceptor. Each enzyme had a half-life of greater than 3 hours at 70{degree}C. With F{sub 420} as the substrate, the F{sub 420}-active enzyme was less thermostable and lost half its activity in about 70 min at 70{degree}C.
- Research Organization:
- Cornell Univ., Ithaca, NY (USA)
- OSTI ID:
- 6348687
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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HYDROGENASES
FRACTIONATION
METHANE
YIELDS
METHANOGENIC BACTERIA
GROWTH
BIOLOGICAL HALF-LIFE
CHEMICAL COMPOSITION
HIGH PRESSURE
ION EXCHANGE CHROMATOGRAPHY
MEDIUM TEMPERATURE
PH VALUE
ALKANES
BACTERIA
CHROMATOGRAPHY
ENZYMES
HYDROCARBONS
MICROORGANISMS
ORGANIC COMPOUNDS
OXIDOREDUCTASES
SEPARATION PROCESSES
090800* - Biomass Fuels- Production- (1990-)