Benguela Upwelling sediments metagenome study

Marine sediments are the largest organic carbon sink on Earth. Microbial activities in sediments drive carbon remineralization, thus these processes have central importance in regulating global carbon cycle and climate. Despite tremendous advances in the study of microbial biogeography in subsurface marine sediments, little is known about the factors determining microbial community structure or the metabolism of the majority of subsurface microbes. In particular, the relationship between organic matter composition in sediments and microbial community structure is poorly understood.Since organic matter can differ considerably in terms of chemical composition depending by age, source and sedimentary settings, I hypothesize that the macromolecular composition of buried organic matter could be one key factor in shaping subseafloor microbial communities.To address this hypothesis I analyzed community composition on a transect spanning from continental shelf to abyssal plain - reflecting different chemical composition of organic matter - in one of the most productive systems on Earth, the Benguela Upwelling System. To elucidate what are the communities' metabolic capabilities and how these are changing across the continental margin in relation to organic matter composition I performed metagenomic sequencing on three subsurface samples representative of different sedimentary settings. This will be the first study comparing metagenomes across a defined environmental gradient in marine subsurface environments.This project will contribute to answering question as “what are the ecological rules shaping subsurface community structure and biogeography”, and “what are the principal pathways of carbon transformation in marine subsurface environments”.