Methane is one of the most potent greenhouse gases and previous studies suggested that it is removed from the atmosphere through aerobic and anaerobic processes with the help of bacteria and archaea. Recent evidence suggests, however, that methane can be removed through other pathways involving as-yet unidentified microbes.
To learn more about these pathways and help establish their roles in the global carbon cycle, researchers led by longtime DOE Joint Genome Institute collaborator Ludmila Chistoserdova sequenced and analyzed DNA sequences from microbial communities collected from sediment samples of Lake Washington.
In their report published February 19, 2013 in the open-access journal PeerJ, the team identified several genomes representing two dominant methane-oxidizing microbial families, Methylococcaceae and Methylophilaceae. Under aerobic conditions, the team reported, species of Methylococcaceae harnessed methane with “some type of a cooperative behavior” involving species of Methylophilaceae.
The team looked for genes crucial to the methane oxidation pathway, but did not find them in some of the microbial species present. They also reported finding “a persistence of genes” that suggested these microbes were involved in nitrogen fixation and denitrification of the lake sediments.
“[T]heir coordinated response to methane and nitrate suggest that these species may be engaged in cooperative behavior, the nature of which remains unknown,” the researchers wrote in their study.