Gilmour, C.C., A.L. Bullock, A. McBurney, M. Podar, and D.A. Elias.
mBio 9:e02403-17(2018)

Archaea, specifically methanogenic organisms, play a role in Hg methylation in nature, but their global importance to MeHg production and the subsequent risk to ecosystems are not known. Methanogenesis has been linked to Hg methylation in several natural habitats where MeHg production incurs risk to people and ecosystems, including rice paddies and permafrost. This research confirmed that most methanogens carrying the hgcAB gene pair are capable of Hg methylation. The investigators found that methylation rates vary inherently among hgcAB⁺ methanogens but that several species are capable of MeHg production at rates that rival those of the better-known Hg-methylating sulfate- and iron-reducing bacteria. Methanogens might need to be considered equally with sulfate and iron reducers in evaluating MeHg production in nature. https://repository.si.edu/bitstream/handle/10088/35591/Gilmour%202018%20mBio%20Robust%20mercury%20methylation%20across%20diverse%20methanogenic%20Archaea.pdf