Aquatic metagenomes implicate Thaumarchaeota in global cobalamin production

Cobalamin (vitamin B12) is a complex metabolite and essential cofactor required by many branches of life, including most eukaryotic phytoplankton. Algae and other cobalamin auxotrophs rely on environmental cobalamin supplied from a relatively small set of cobalamin-producing prokaryotic taxa. Although several Bacteria have been implicated in cobalamin biosynthesis and associated with algal symbiosis, the involvement of Archaea in cobalamin …