ANME-SRB consortia partnerships revealed by FISH staining of a consortium with ANME-2b (blue) and SEEP-SRB1g (green), and another consortium with ANME-2a (red) and SEEP-SRB1a (yellow)
Anaerobic oxidation of methane (AOM) is performed by anaerobic methanotrophic archaea or (ANME). Methane is oxidized by ANME by reversing the methanogenesis pathway, but this is only feasible when it is coupled to an energetically favorable reaction such as sulfate, nitrate or metal reduction. Hence, AOM is most often performed by syntrophic consortia of ANME and syntrophic sulfate reducing bacteria (SRB). We are interested in developing an ecological framework to identify individual syntrophic partnerships, by sampling for these consortia in various field sites and characterizing them both with microscopy, various -omics approaches and stable isotope probing.
The metabolic adaptations are present in both partners as a result of their syntrophic association. Our research has demonstrated that direct interspecies electron transfer from ANME to SRB likely drives the syntrophic partnership. Our lab is also interested in how ANME-SRB use other metabolic strategies typical of syntrophy, such as the exchange of fixed nitrogen between partners. In identifying such metabolic adaptations specific to either partner, we are driving towards understanding the evolution of anaerobic oxidation of methane, a geologically significant process.