Abstract
Wetlands are one of the major sources of atmospheric methane. However, not all methane produced by methanogens reaches the atmosphere as a substantial amount of CH4 (1 to 90%) is recycled in soil aerobic zone by methanotrophic bacteria. It was found that methane oxidation is also conducted by methanotrophic bacteria endosymbionts ofSphagnum mosses. The aims of the study were to examine Sphagnum-involved CH4oxidation in transition moor in Eastern Poland and the molecular studies of methanotrophic communities inhabiting Sphagnum recurvum. The identification of endosymbiotic methanotrophs was performed by polymerase chain reaction (PCR) andfluorescence in situ hybridization (FISH) techniques. The methanotrophic activity of submerged and non-submerged Sphagnum mosses was determined at the level of 7.6±0.1 and 2.5±0.1 mM CH4g-1DWday-1 for complete plants from pool and lawn mosses, respectively. The highest activity was found in the top plants parts. On the basis of genomic analyses, it was found that endosymbionts belonged to methanotrophs of type I and II. The spread of Sphagnum species in peat bogs and the contribution of methanotrophic endosymbionts to methane recycling, (very important in relation to expected climate warming), could be greatly important in predicting the methane fluxes from wetlands. Key words: Methane oxidation, methanotrophs, Sphagnum moss, symbiosis.
Highlights
Methane is one of the most important greenhouse gases
The first acidophilic methanotrophs were isolated from Sphagnum peat bogs in East bp of Siberia and North Russia boreal forests were qualified as the type of Methylocella sp. and Methylocapsa sp. (Dedysh et al, 1998 a,b, 2004)
In 2005, Raghoebrasing and co-workers showed the presence of first methanotrophic bacteria inhabiting the hyaline cells and on the steam leaves of Sphagnum sp. originating from Dutch peat bogs
Summary
Methane is one of the most important greenhouse gases. Because of its relatively low mixing ratio (c.a. 1774 ppb) (IPCC, 2001), CH4 is considered to contribute to about 20% of global warming effect (EPA, 2006). It was confirmed that global methane budget is strongly influenced by anthropogenic emissions (IPCC, 2001, 2007; Wuebbles, 2002), still the largest methane part (c.a. 37 %) entering the atmosphere annually originates from wetlands (IPCC 2001, 2007) Another way of the wetlands impact on the composition of the atmosphere and, in particular on methane mixing ratio is their ability to act as an active CH4 sink. It was confirmed, that substantial amount of CH4 (1 to 90%) is recycled in aerobic zone by methanotrophic bacteria and does not reach the atmosphere (Segers, 1998; Marani and Alvalá, 2006; Freeman et al, 2002; Dinsmore et al, 2009). The participation of wetland CH4 in global methane emissions makes understanding and assessment of CH4 sink-source relationships in peatlands crucial for global warming processes (Freeman et al, 2002)
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