title: Marine planktonic archaea take up amino acids.
abstract: Archaea are traditionally thought of as "extremophiles," but recent studies have shown that marine planktonic Archaea make up a surprisingly large percentage of ocean midwater microbial communities, up to 60% of the total prokaryotes. However, the basic physiology and contribution of Archaea to community microbial activity remain unknown. We have studied Archaea from 200-m depths of the northwest Mediterranean Sea and the Pacific Ocean near California, measuring the archaeal activity under simulated natural conditions (8 to 17 degrees C, dark and aerobic [corrected]) by means of a method called substrate tracking autoradiography fluorescence in situ hybridization (STARFISH) that simultaneously detects specific cell types by 16S rRNA probe binding and activity by microautoradiography. In the 200-m-deep Mediterranean and Pacific samples, cells binding the archaeal probes made up about 43 and 14% of the total countable cells, respectively. Our results showed that the Archaea are active in the uptake of dissolved amino acids from natural concentrations (nanomolar) with about 60% of the individuals in the archaeal communities showing measurable uptake. Bacteria showed a similar proportion of active cells. We concluded that a portion of these Archaea is heterotrophic and also appears to coexist successfully with Bacteria in the same water.
authors.affiliation: Department of Biological Sciences, University of Southern California, Los Angeles, California 90089-0371, USA. ouverney@stanford.edu
authors.forename: C C
authors.initials: CC
authors.lastname: Ouverney
authors.forename: J A
authors.initials: JA
authors.lastname: Fuhrman
mesh_terms: D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D001105:Archaea / Q000254:growth & development / Q000378:metabolism*; D001345:Autoradiography / Q000379:methods; D015169:Colony Count, Microbial; D017403:In Situ Hybridization / Q000379:methods; D008828:Microbiological Techniques / Q000379:methods; D010933:Plankton / Q000254:growth & development; D012623:Seawater / Q000382:microbiology*
chemical_list: D000596:Amino Acids