title: Origin, dynamics, and implications of extracellular DNA pools in marine sediments.
abstract: In marine sediments, DNA occurs both inside and outside living organisms. DNA not enclosed in living cells may account for the largest fraction of total DNA, and include molecules locked within dead cells, organic and inorganic aggregates, adsorbed onto mineral matrices, and viral DNA. This DNA comprises genetic material released in situ from sediment microbial communities, as well as DNA of pelagic and terrestrial origin deposited to the seafloor. DNA not enclosed in living cells undermines the assumption of a direct link between the overall DNA pool and the local, currently living microbial assemblages, in terms of both microbial cell abundance and diversity. At the same time, the extracellular DNA may provide an integrated view of the biodiversity and ecological processes occurring on land, in marine water columns, and sediments themselves, thereby acting as an archive of genetic information which can be used to reconstruct past changes in source environments. In this review, we identify and discuss DNA pools in marine sediments, with special focus on DNA not enclosed in living cells, its origin, dynamics, and ecological and methodological implications. Achievements in deciphering the genetic information held within each DNA pool are presented along with still-standing challenges and major gaps in current knowledge.
authors.affiliation: Center for Geomicrobiology, Department for Bioscience, Aarhus University, Ny Munkegade 116, Building 1535 DK-8000 Aarhus C, Denmark. Electronic address: torti@bios.au.dk.
authors.forename: Andrea
authors.initials: A
authors.lastname: Torti
authors.affiliation: Institute of Biogeochemistry and Pollutant Dynamics, Department of Environmental Systems Sciences, Swiss Federal Institute of Technology Zurich (ETHZ), Universitätstrasse 16, 8092, Zürich, Switzerland. Electronic address: mark.lever@usys.ethz.ch.
authors.forename: Mark Alexander
authors.initials: MA
authors.lastname: Lever
authors.affiliation: Center for Geomicrobiology, Department for Bioscience, Aarhus University, Ny Munkegade 116, Building 1535 DK-8000 Aarhus C, Denmark. Electronic address: bo.barker@bios.au.dk.
authors.forename: Bo Barker
authors.initials: BB
authors.lastname: Jørgensen
mesh_terms: D000818:Animals; D059001:Aquatic Organisms / Q000145:classification* / Q000235:genetics*; D044822:Biodiversity; D004247:DNA / Q000737:chemistry / Q000145:classification / Q000235:genetics*; D019015:Geologic Sediments / Q000737:chemistry*
chemical_list: D004247:DNA
keywords: Ancient DNA; Extracellular RNA; Fossil DNA; Microbial diversity; Non-soluble DNA; Soluble DNA