Methane oxidation by Nitrosococcus oceanus and Nitrosomonas europaea
Chemolithotrophic ammonium-oxidizing bacteria were examined as to their ability to oxidize methane in the absence of ammonium or nitrite. The addition of ammonium stimulated both CO/sub 2/ production and cellular incorporation of methane-carbon by N. oceanus and N. europaea. Less than 0.1 mM CH/sub 4/ in solution inhibited the oxidation of ammonium by N. oceanus by 87% but had no inhibitory effects on N. europaea. In the absence of NH/sub 4/-N, N. oceanus achieved a maximum methane oxidation rate of 2.20 x 10/sup -2/ ..mu..mol of CH/sub 4/ h/sup -1/ mg (dry weight) of cells/sup -1/, which remained constant as the methane concentration was increased. In the presence of NH/sub 4/-N (10 ppm (10 ..mu..g/ml)), its maximum rate was 26.4 x 10/sup -2/ ..mu..mol of CH/sub 4/ h/sup -1/ mg (dry weight) of cells/sup -1/ at a methane concentration of 1.19 x 10/sup -1/ mM. Increasing the methane concentrations above this level decreased CO/sub 2/ production, whereas cellular incorporation of methane-carbon continued to increase. N. europaea showed a linear response throughout the test range, with an activity of 196.0 x 10/sup -2/ ..mu..mol of CH/sub 4/ h/sup -1/ mg (dry weight) of cells/sup -1/ at a methane concentration of 1.38 x 10/sup -1/ mM. Both nitrite and nitrate stimulated the oxidation of methane. The pH range was similar to that for ammonium oxidation, but the points of maximum activity were at lower values for the oxidation of methane. (JMT)
- Research Organization:
- Oregon State Univ., Corvallis
- OSTI ID:
- 5896587
- Journal Information:
- Appl. Environ. Microbiol.; (United States), Journal Name: Appl. Environ. Microbiol.; (United States) Vol. 45:2; ISSN AEMID
- Country of Publication:
- United States
- Language:
- English
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