Methanotrophic bacteria in boreal forest soil after fire.

Methane-oxidizing bacteria are the only terrestrial sink for atmospheric methane. Little is known, however, about the methane-oxidizing bacteria that are responsible for the consumption of atmospheric methane, or about the factors that influence their activity and diversity in soil. Effects of fire and its end-product, wood ash, on the activity and community of methane oxidizing bacteria were studied in boreal forest 3 months and 12 years after the treatments. Fire significantly increased the atmospheric CH(4) oxidation rate. Both fire and wood ash treatments resulted in increased soil pH, but there was no correlation with methane oxidation rates. Changes in the methane-oxidizing bacterial community due to treatments were not detected by cultivation-independent recovery and comparative sequence analysis of pmoA gene products from soil. Phylogenetic analysis showed that a majority of the pmoA sequences obtained belonged to the "upland soil cluster alpha", which has previously been detected in diverse forest environments.