title: Virus-mediated archaeal hecatomb in the deep seafloor.
abstract: Viruses are the most abundant biological entities in the world's oceans, and they play a crucial role in global biogeochemical cycles. In deep-sea ecosystems, archaea and bacteria drive major nutrient cycles, and viruses are largely responsible for their mortality, thereby exerting important controls on microbial dynamics. However, the relative impact of viruses on archaea compared to bacteria is unknown, limiting our understanding of the factors controlling the functioning of marine systems at a global scale. We evaluate the selectivity of viral infections by using several independent approaches, including an innovative molecular method based on the quantification of archaeal versus bacterial genes released by viral lysis. We provide evidence that, in all oceanic surface sediments (from 1000- to 10,000-m water depth), the impact of viral infection is higher on archaea than on bacteria. We also found that, within deep-sea benthic archaea, the impact of viruses was mainly directed at members of specific clades of Marine Group I Thaumarchaeota. Although archaea represent, on average, ~12% of the total cell abundance in the top 50 cm of sediment, virus-induced lysis of archaea accounts for up to one-third of the total microbial biomass killed, resulting in the release of ~0.3 to 0.5 gigatons of carbon per year globally. Our results indicate that viral infection represents a key mechanism controlling the turnover of archaea in surface deep-sea sediments. We conclude that interactions between archaea and their viruses might play a profound, previously underestimated role in the functioning of deep-sea ecosystems and in global biogeochemical cycles.
authors.affiliation: Department of Life and Environmental Sciences, Polytechnic University of Marche, Ancona 60131, Italy.; Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Naples, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Danovaro
authors.affiliation: Department of Life and Environmental Sciences, Polytechnic University of Marche, Ancona 60131, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Dell'Anno
authors.affiliation: Department of Life and Environmental Sciences, Polytechnic University of Marche, Ancona 60131, Italy.; Department of Sciences and Engineering of Materials, Environment and Urbanistics, Polytechnic University of Marche, Ancona 60131, Italy.
authors.forename: Cinzia
authors.initials: C
authors.lastname: Corinaldesi
authors.affiliation: Department of Life and Environmental Sciences, Polytechnic University of Marche, Ancona 60131, Italy.; Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Naples, Italy.
authors.forename: Eugenio
authors.initials: E
authors.lastname: Rastelli
authors.affiliation: School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia.
authors.forename: Ricardo
authors.identifier: 0000-0001-8989-6402
authors.initials: R
authors.lastname: Cavicchioli
authors.affiliation: Unité de Biologie Moléculaire du Gène chez les Extrêmophiles, Institut Pasteur, Paris 75015, France.
authors.forename: Mart
authors.identifier: 0000-0001-5486-0098
authors.initials: M
authors.lastname: Krupovic
authors.affiliation: Institute of Marine Sciences, University of North Carolina at Chapel Hill, Morehead City, NC 28557, USA.
authors.forename: Rachel T
authors.identifier: 0000-0001-9071-8312
authors.initials: RT
authors.lastname: Noble
authors.affiliation: Institute of Biogeosciences, Japan Agency for Marine-Earth Science and Technology, Natsushima-cho, Yokosuka 237-0061, Japan.
authors.forename: Takuro
authors.identifier: 0000-0003-2323-0880
authors.initials: T
authors.lastname: Nunoura
authors.affiliation: Unité de Biologie Moléculaire du Gène chez les Extrêmophiles, Institut Pasteur, Paris 75015, France.
authors.forename: David
authors.initials: D
authors.lastname: Prangishvili
mesh_terms: D001105:Archaea / Q000254:growth & development / Q000821:virology; D023641:Archaeal Viruses / Q000502:physiology*; D017753:Ecosystem; D009792:Oceans and Seas; D014871:Water Microbiology
keywords: Deep-sea ecosystems; archaea; bacteria; biodiversity; ecosystem functioning; microbial loop; virus-host interactions