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Methane Oxidation by Nitrosococcus oceanus and Nitrosomonas europaea
1Department of Microbiology and School of Oceanography, Oregon State University, Corvallis, Oregon 97331.
Applied and Environmental Microbiology
|February 1, 1983
Summary
Certain ammonium-oxidizing bacteria can metabolize methane, converting it to CO2 and cellular components. Nitrite-oxidizing bacteria, however, cannot oxidize methane, highlighting distinct metabolic capabilities within these microbial groups.
Area of Science:
- Microbiology
- Environmental Science
- Biochemistry
Background:
- Chemolithotrophic bacteria play crucial roles in nutrient cycling.
- Ammonium-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) are key players in nitrification.
- The metabolic potential of these bacteria beyond their primary roles is an area of ongoing research.
Purpose of the Study:
- To investigate the methane oxidation capabilities of AOB and NOB.
- To determine the influence of environmental factors like substrate concentration and pH on methane oxidation by AOB.
- To compare the methane oxidation potential between different bacterial species.
Main Methods:
- Selected AOB (Nitrosomonas europaea, Nitrosococcus oceanus) and NOB (Nitrobacter sp., Nitiospina gracilis, Nitrococcus mobilis) were cultured.
- Methane oxidation was measured by CO2 production and cellular incorporation of methane-carbon.
- Experiments were conducted under varying concentrations of methane, ammonium, and different nitrogen sources.
- The effect of pH on methane oxidation was also assessed.
Main Results:
- All tested AOB, including Nitrosomonas europaea and Nitrosococcus oceanus, oxidized methane to CO2 and biomass.
- NOB species did not exhibit methane oxidation activity.
- Ammonium significantly stimulated methane oxidation in both Nitrosococcus oceanus and Nitrosomonas europaea.
- Methane concentrations showed varying inhibitory effects on ammonium oxidation depending on the bacterial species.
- Nitrite and nitrate also stimulated methane oxidation in AOB.
Conclusions:
- Ammonium-oxidizing bacteria possess the metabolic capacity for methane oxidation, a function not found in nitrite-oxidizing bacteria.
- Environmental factors such as substrate availability and pH critically influence the efficiency of methane oxidation by AOB.
- This finding expands our understanding of the ecological roles and metabolic versatility of ammonium-oxidizing bacteria in methane cycling.