Characterization of Methanotrophic Communities in Soils from Regions with Different Environmental Settings

Abstract

Methanotrophic communities from freshwater wetland (FW), seawater wetland (SW), forest (FS), and landfillsoils (LS) around Seoul of South Korea, were characterized using comparative sequence analyses of clonelibraries. Proportions of Methylocaldum, Methlyococcus and Methylosinus were found to be greater in FW andSW, while Methylobacter and Methylomonas were more notable in FS and Methylocystis and Methylomicro-bium more prominent in LS. Lag periods behind the initiation of methane oxidation significantly variedamongst the soils. Methane oxidation rates were greater in FW≥LS≥SW>FS (p<0.05). Thus, the environmen-tal setting is a significant factor influencing the communities and capabilities of methanotrophs.Keywords: Methanotrophs, clone library, environmental setting, methane oxidation potentialThere are diverse methanotrophs in natural environmentswhere they utilize methane as their sole source of carbonand energy. Environmental characteristics such as climatic,physiographic, geologic, biotic, and land-use features candetermine growth and activity of methanotrophs. For instance,methane concentration is a key determinant for methanotro-phic community composition as well as characteristics ofmethane oxidation [6, 9, 11, 13]. Methanotrophs in well-aerated upland soils show a high enzymatic affinity formethane since they grow on atmospheric methane [1, 9]. Incontrast, methanotrophs in wetland or landfill soils mayhave lower enzymatic affinity levels since they grow onmethane produced in the soils or emitted from the landfills,respectively. The main objective in the present study was totest hypotheses that environmental setting can determinewhether a specific type of methanotrophs is present, andthat it also can determine methane-oxidation potential ofmethanotrophs.We defined methanotrophic communities and characterizedCH