Abstract
In the Giessen free-air CO2 enrichment (GiFACE) experiment, 5 years of CO2 enrichment led to decreased CH4 uptake rates of the investigated meadow soil. In soils, CH4 is mainly oxidised by methanotrophic bacteria. In the present study, abundances of methanotrophic bacteria and total bacteria in soil samples from the GiFACE experiment were quantified by applying pmoA- and 16S rRNA gene-targeted real-time PCR and fluorescence in situ hybridisation (FISH). Methanotrophic bacteria of the Methylosinus group (Alphaproteobacteria) and the Methylobacter/Methylosarcina group (Gammaproteobacteria) were detectable by real-time PCR as well as by FISH. Both quantitative analytical approaches revealed that abundances of either bacteria or methanotrophic bacteria in soil samples from sites under CO2-enriched atmosphere were decreased. Compared to ambient site, only 46 and 30.5% of methanotrophic bacteria and 38 and 63.2% of total bacterial cell numbers could be detected under CO2-enriched atmosphere by FISH and real-time PCR, respectively. These results suggest that significantly decreased abundances of methanotrophic bacteria could explain reduced CH4 uptake rates.
Published Version
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