ABSTRACTSphagnumpeatlands are important ecosystems in the methane cycle. Methane-oxidizing bacteria in these ecosystems serve as a methane filter and limit methane emissions. Yet little is known about the diversity and identity of the methanotrophs present in and onSphagnummosses of peatlands, and only a few isolates are known. The methanotrophic community inSphagnummosses, originating from a Dutch peat bog, was investigated using apmoAmicroarray. A high biodiversity of both gamma- and alphaproteobacterial methanotrophs was found. WithSphagnummosses as the inoculum, alpha- and gammaproteobacterial acidophilic methanotrophs were isolated using established and newly designed media. The 16S rRNA,pmoA,pxmA, andmmoXgene sequences showed that the alphaproteobacterial isolates belonged to theMethylocystisandMethylosinusgenera. TheMethylosinusspecies isolated are the first acid-tolerant members of this genus. Of the acidophilic gammaproteobacterial strains isolated, strain M5 was affiliated with theMethylomonasgenus, and the other strain, M200, may represent a novel genus, most closely related to the generaMethylosomaandMethylovulum. So far, no acidophilic or acid-tolerant methanotrophs in theGammaproteobacteriaclass are known. All strains showed the typical features of either type I or II methanotrophs and are, to the best of our knowledge, the first isolated (acidophilic or acid-tolerant) methanotrophs fromSphagnummosses.
Isolation and characterization of oligotrophic acido-tolerant methanogenic consortia from a Sphagnum peat bog