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Effects of O 2 and CH 4 on presence and activity of the indigenous methanotrophic community in rice field soil
Author(s) -
Henckel Thilo,
Roslev Peter,
Conrad Ralf
Publication year - 2000
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1046/j.1462-2920.2000.00149.x
Subject(s) - methane monooxygenase , methanotroph , biology , anaerobic oxidation of methane , paddy field , microbial population biology , population , methane , 16s ribosomal rna , environmental chemistry , bacteria , soil water , temperature gradient gel electrophoresis , food science , ecology , chemistry , genetics , demography , sociology
The activity and distribution of methanotrophs in soil depend on the availability of CH 4 and O 2 . Therefore, we investigated the activity and structure of the methanotrophic community in rice field soil under four factorial combinations of high and low CH 4 and O 2 concentrations. The methanotrophic population structure was resolved by denaturant gradient gel electrophoresis (DGGE) with different PCR primer sets targeting the 16S rRNA gene, and two functional genes coding for key enzymes in methanotrophs, i.e. the particulate methane monooxygenase ( pmo A) and the methanol dehydrogenase ( mxa F). Changes in the biomass of type I and II methanotrophic bacteria in the rice soil were determined by analysis of phospholipid‐ester‐linked fatty acid (PLFA) biomarkers. The relative contribution of type I and II methanotrophs to the measured methane oxidation activity was determined by labelling of soil samples with 14 CH 4 followed by analysis of [ 14 C]‐PLFAs. CH 4 oxidation was repressed by high O 2 (20.5%), and enhanced by low O 2 (1%). Depending on the CH 4 and O 2 mixing ratios, different methanotrophic communities developed with a higher diversity at low than at high CH 4 concentration as revealed by PCR‐DGGE. However, a prevalence of type I or II populations was not detected. The [ 14 C]‐PLFA fingerprints, on the other hand, revealed that CH 4 oxidation activity was dominated by type I methanotrophs in incubations with low CH 4 mixing ratios (1000 p.p.m.v.) and during initiation of CH 4 consumption regardless of O 2 or CH 4 mixing ratio. At high methane mixing ratios (10 000 p.p.m.v.), type I and II methanotrophs contributed equally to the measured CH 4 metabolism. Collectively, type I methanotrophs responded fast and with pronounced shifts in population structure and dominated the activity under all four gas mixtures. Type II methanotrophs, on the other hand, although apparently more abundant, always present and showing a largely stable population structure, became active later and contributed to CH 4 oxidation activity mainly under high CH 4 mixing ratios.