Kinetics of formate metabolism in Methanobacterium formicicum and Methanospirillum hungatei
The kinetics of formate metabolism in Methanobacterium formicicum and Methanospirillum hungatei were studied with log-phase formate-grown cultures. The progress of formate degradation was followed by the formyltetrahydrofolate synthetase assay for formate and fitted to the integrated form of the Michaelis-Menten equation. The Km and Vmax values for Methanobacterium formicicum were 0.58 mM formate and 0.037 mol of formate/h/g (dry weight), respectively. The lowest concentration of formate metabolized by Methanobacterium formicicum was 26 muM. The Km and Vmax values for Methanospirillum hungatei were 0.22 mM and 0.044 mol of formate/h/g (dry weight), respectively. The lowest concentration of formate metabolized by Methanospirillum hungatei was 15 muM. The apparent Km for formate by formate dehydrogenase in cell-free extracts of Methanospirillum hungatei was 0.11 mM. The Km for H2 uptake by cultures of Methanobacterium formicicum was 6 muM dissolved H2. Formate and H2 were equivalent electron donors for methanogenesis when both substrates were above saturation; however, H2 uptake was severely depressed when formate was above saturation and the dissolved H2 was below 6 muM. Formate-grown cultures of Methanobacterium formicicum that were substrate limited for 57 h showed an immediate increase in growth and methanogenesis when formate was added to above saturation. (Refs. 16).
- Research Organization:
- Dept of Anaerobic Microbiology, Virginia Polytechnic Inst and State Univ, Blacksburg, VA 24061
- OSTI ID:
- 6221926
- Journal Information:
- Appl. Environ. Microbiol.; (United States), Vol. 44:3
- Country of Publication:
- United States
- Language:
- English
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