Freshwater chemosynthetic mat community metagenomic assembly

Little is known about large sulfur bacteria that inhabit sulfidic groundwater seeps in large lakes. To examine how geochemicallyrelevant microbial metabolisms are partitioned among community members, we conducted metagenomic analysis of a chemosynthetic microbial mat in the Isolated Sinkhole, which is in a deep, aphotic environment of Lake Huron. For comparison, we also analyzed a white mat in an artesian fountain that is fed by groundwater similar to Isolated Sinkhole, but that sits in shallow water and is exposed to sunlight. Our results show that groundwater-fed communities in an artesian fountain and in submerged sinkholes of Lake Huron are a rich source of novel large sulfur bacteria, associated heterotrophic and sulfate-reducing bacteria, and enigmatic archaea.