Transformation of iodate to iodide in marine phytoplankton driven by cell senescence

Abstract

AB Aquatic Biology Contact the journal Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AB 11:1-15 (2010) - DOI: https://doi.org/10.3354/ab00284 FEATURE ARTICLE Transformation of iodate to iodide in marine phytoplankton driven by cell senescence K. Bluhm1,*, P. Croot1, K. Wuttig1, K. Lochte2 1IFM-GEOMAR, Leibniz Institute for Marine Sciences, Marine Biogeochemistry, Westshore Building, Duesternbrooker Weg 20, 24105 Kiel, Germany 2Alfred-Wegener-Institute for Polar- and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany *Email: kbluhm@ifm-geomar.de ABSTRACT: Previous studies have suggested that phytoplankton play an important role in the biogeochemical cycling of iodine, due to the appearance of iodide in the euphotic zone. Changes in the speciation of iodine over the course of the growth cycle were examined in culture media for a variety of phytoplankton taxa (diatoms, dinoflagellates and prymnesiophytes). All species tested showed the apparent ability to reduce iodate to iodide, though production rates varied considerably between species (0.01 to 0.26 nmol l–1 µg–1 chl a d–1), with Eucampia antarctica the least and Pseudo-nitzschia turgiduloides the most efficient iodide producers. Production was found to be species specific and was not related to biomass (indicated by e.g. cell size, cell volume, or chl a content). In all species, except for the mixotrophic dinoflagellate Scrippsiella trochoidea, iodide production commenced in the stationary growth phase and peaked in the senescent phase of the algae, indicating that iodide production is connected to cell senescence. This suggests that iodate reduction results from increased cell permeability, which we hypothesize is due to subsequent reactions of iodate with reduced sulphur species exuded from the cell. A shift from senescence back to the exponential growth phase resulted in a decline in iodide and indicated that phytoplankton-mediated oxidation of iodide to iodate was likely to be occurring. Iodide production could not be observed in healthy cells kept in the dark for short periods. Bacterial processes appeared to play only a minor role in the reduction of iodate to iodide. KEY WORDS: Iodine speciation · Iodide · Iodate · Antarctic diatoms · Nitrate reductase · Glutathione · Sulphur species · Cell senescence Full text in pdf format Information about this Feature Article NextCite this article as: Bluhm K, Croot P, Wuttig K, Lochte K (2010) Transformation of iodate to iodide in marine phytoplankton driven by cell senescence. Aquat Biol 11:1-15. https://doi.org/10.3354/ab00284 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AB Vol. 11, No. 1. Online publication date: October 28, 2010 Print ISSN: 1864-7782; Online ISSN: 1864-7790 Copyright © 2010 Inter-Research.