MEDEA · Microbial Ecology of the DEep Atlantic pelagic realm

The project aims at elucidating a major enigma in microbial ecology, i.e., the metabolic activity of prokaryotic communities in the deep sea under in situ pressure conditions, rather than under surface pressure conditions, as commonly done. Analysis of the global data set of prokaryotic abundance indicates that about 40% of prokaryotes reside in depth below 1000m depth with a phylogenetic composition different from that in surface waters. Using a recently fabricated high-pressure sampling and incubation system in combination with advanced tools to assess phylogenetic diversity, gene expression and single-cell activity, we will be able to resolve this enigma on a prokaryotic community level as well as on a phylotype level. This detailed knowledge on the distribution of the auto- and heterotrophic activity of deep-sea prokaryotes under in situ pressure conditions is essential to refine our view on the oceanic biogeochemical cycles, and to obtain a mechanistic understanding of the functioning of deep-sea microbial food webs.