Methanotrophic Activity and Diversity Decrease in Response to Spruce-Derived Monoterpenes
2 Lehrstuhl für Bodenökologie, Universität Bayreuth
O 1.5 in Funktion von Ökosystemen
02.04.2009, 11:30-11:45, H8
Methanotrophic communities in soils under Norway spruce (Picea abies) exhibit up to three times lower annual methane consumption than those under European beech (Fagus sylvatica). The aim of this study was to resolve reasons causing this difference and determine their effect on the methanotrophic community. Adjacent beech and spruce soils from three temperate forests (Solling, Steigerwald, and Unterlüß, Germany) were investigated. Continuous flow microcosms with intact soil cores at constant methane concentrations, temperature, and matric potential indicated that maximal methane oxidation rates (Vmax(app)) and Michaelis Menten constants (KM(app)) were two times higher in beech than in spruce soils. Monoterpenes were abundant in spruce samples, whereas they were hardly detectable in beech samples. Supplemented β-pinene resulted in a 90% inhibition of atmospheric methane oxidation at concentrations that were two times higher than in spruce soils. Thus, a reduction of methane consumption by a factor of three in spruce soils was likely attributed to monoterpenes. Methanotrophic community structure was assessed by functional gene analysis. pmoA genotypes from all soils affiliated mainly with subclusters within the upland soil cluster alpha. Two further distinct sequence clusters with low similarities to known pmoA or amoA genotypes were detected. Several independent statistical approaches indicated that detectable methanotrophic diversity was higher in beech than in spruce soils. These collective results suggest that specific monoterpenes from Norway spruce litter and roots decrease the activity and diversity of methanotrophs and might explain the decreased capacity of spruce soils to consume atmospheric methane.
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