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R. D. , A. D. , C. C. , R. N. , C. C. et al., contributed to data elaboration. All authors discussed and wrote the manuscript and commented on the paper. Competing interests: The authors declare that they have no competing interests. Data and materials availability: All data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Materials. Additional data related to this paper may be requested from the authors. The sequences of the viromes and of the ribosomal genes analyzed in this paper have been deposited in MetaVir (metavir-meb.univ-bpclermont.fr) and in MG-RAST (metagenomics.anl.gov), respectively, I31J10000060001) and by the European Commission Seventh Framework Program Project MIDAS (Managing Impacts of Deep-seA reSource exploitation, pp.1-6

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