Emerging concepts on microbial processes in the bathypelagic ocean - ecology, biogeochemistry, and genomics

Toshi Nagata, Christian Tamburini, Javier Aristegui, Federico Baltar, Alexander B. Bochdansky, Serena Fonda-Umani, Hideki Fukuda, Alexandra Gogou, Dennis. A. Hansell, Roberta L. Hansman, Gerhard J. Herndl, Christos Panagiotopoulos, Thomas Reinthaler, Rumi Sohrin, Pedro Verdugo, Namiha Yamada, Youhei Yamashita, Taichi Yokokawa, Douglas H. Bartlett

This paper synthesizes recent findings regarding microbial distributions and processes in the bathypelagic ocean (depth > 1000 m). Abundance, production and respiration of prokaryotes reflect supplies of particulate and dissolved organic matter to the bathypelagic zone. Better resolution of carbon fluxes mediated by deep microbes requires further testing on the validity of conversion factors. Archaea, especially marine Crenarchaeota Group I, are abundant in deep waters where they can fix dissolved inorganic carbon. Viruses appear to be important in the microbial loop in deep waters, displaying remarkably high virus to prokaryote abundance ratios in some oceanic regions. Sequencing of 18S rRNA genes revealed a tremendous diversity of small-sized protists in bathypelagic waters. Abundances of heterotrophic nanoflagellates (HNF) and ciliates decrease with depth more steeply than prokaryotes; nonetheless, data indicated that HNF consumed half of prokaryote production in the bathypelagic zone. Aggregates are important habitats for deep-water microbes, which produce more extracellular enzymes (on a per-cell basis) than surface communities. The theory of marine gel formation provides a framework to unravel complex interactions between microbes and organic polymers. Recent data on the effects of hydrostatic pressure on microbial activities indicate that bathypelagic microbial activity is generally higher under in situ pressure conditions than at atmospheric pressures. High-throughput sequencing of 16S rRNA genes revealed a remarkable diversity of Bacteria in the bathypelagic ocean. Metagenomics and comparative genomics of piezophiles reveal not only the high diversity of deep sea microbes but also specific functional attributes of these piezophilic microbes, interpreted as an adaptation to the deep water environment. Taken together, the data compiled on bathypelagic microbes indicate that, despite high-pressure and low-temperature conditions, microbes in the bathypelagic ocean dynamically interact with complex mixtures of organic matter, responding to changes in the ocean's biogeochemical state. (C) 2010 Elsevier Ltd. All rights reserved.

Functional and Evolutionary Ecology
External organisation(s)
Università degli Studi di Trieste, Royal Netherlands Institute for Sea Research, University of Tokyo, Aix-Marseille Université, Universidad de Las Palmas de Gran Canaria, Old Dominion University, Hellenic Centre for Marine Research, University of Miami, Shizuoka University, University of Washington, National Institute of Advanced Industrial Science and Technology (AIST), Florida International University, University of California, San Diego
Deep-Sea Research. Part 2: Topical Studies in Oceanography
No. of pages
Publication date
Peer reviewed
Austrian Fields of Science 2012
106021 Marine biology
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