2004. pmoA-based analysis of methanotrophs in a littoral lake sediment reveals a diverse and stable community in a dynamic environment. Appl Environ Microbiol

Diversity and community structure of aerobic methane-oxidizing bacteria in the littoral sediment of Lake Constance was investigated by cloning analysis and terminal restriction fragment length polymorphism (T-RFLP) fingerprinting of the pmoA gene. Phylogenetic analysis revealed a high diversity of type I and type II methanotrophs in the oxygenated uppermost centimeter of the sediment. T-RFLP profiles indicated a high similarity between the active methanotrophic community in the oxic layer and the inactive community in an anoxic sediment layer at a 10-cm depth. There were also no major changes in community structure between littoral sediment cores sampled in summer and winter. By contrast, the fingerprint patterns showed substan-tial differences between the methanotrophic communities of littoral and profundal sediments. Aerobic methane-oxidizing bacteria (methanotrophs) play an important role in controlling methane fluxes from anoxic environments to the atmosphere (11, 19). In freshwater sedi-ments, the activity of methanotrophs is largely restricted to a narrow layer at the oxic-anoxic interface, where methane and oxygen gradients overlap (5, 28, 33). In the case of Lake Constance, where oxygen penetrate