Growth of sedimentaryBathyarchaeotaon lignin as an energy source

Significance Marine sediment holds the largest organic carbon pool on earth, where microbial transformation of carbon is considered a key process of carbon cycling. Bathyarchaeota are among the most abundant and active groups of microorganisms in marine sediment. It has been suggested that Bathyarchaeota may play a globally important role in the carbon cycling in the marine environment through fermentation of complex organic substances, acetogenesis, and methanogenesis based on metagenome analysis. Here we provide several lines of converging evidence suggesting the bathyarchaeotal group Bathy-8 is able to grow with lignin as an energy source and bicarbonate as a carbon source. Consequently, members of the Bathyarchaeota are probably important, previously unrecognized degraders of lignin.