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Short-term uptake of dissolved organic nitrogen by an axenic strain of Ulva pertusa (Chlorophyceae) using [15]N isotope measurements

  • Kenji Tarutani , Yoko Niimura and Takuji Uchida
Published/Copyright: June 1, 2005
Botanica Marina
From the journal Volume 47 Issue 3

Abstract

Uptake rates of dissolved organic nitrogen (DON; urea, alanine and glutamate) by Ulva pertusa were determined using axenic cultures and 15N isotopic tracers. When urea or alanine was added to N-starved cultures, the incorporation of 15N into algal tissue was found at all concentrations tested (0.5–40 μM). Maximum uptake rates were 7.92 and 3.00 μmol N g−1 dw h−1, and half-saturation constants were 25.5 and 27.6 μM for urea and alanine, respectively. These results show that U. pertusa can take up urea and alanine directly without bacterial decomposition to inorganic nitrogen. Therefore, U. pertusa is able to utilize certain species of DON, and has the potential to regulate DON fluxes and transformations in coastal environments.

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Published Online: 2005-06-01
Published in Print: 2004-07-12

Copyright © 2004 by Walter de Gruyter GmbH & Co. KG

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