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Ammonium and methylamine transport by the ectomycorrhizal fungus Paxillus involutus and ectomycorrhizas

Author

Summary, in English

Using [C-14]methylamine as an analogue of ammonium, the kinetics and the energetics of NH: transport were studied in the ectomycorrhizal fungus, Paxillus involutus (Batsch) Fr. The apparent half-saturation constant (K-m) and the maximum uptake rate (V-max) for the carrier-mediated transport derived from the Eadie-Hofstee transformation were 180 mu M and 380 nmol (mg dry wt)(-1) min(-1,) respectively. Both pH dependence and inhibition by protonophores indicate that methylamine transport in P. involutus was dependent on the electrochemical H+ gradient. Both long-term and short-term uptake experiments were consistent with regulation of ammonium/methylamine transport processes by the presence of an organic nitrogen source. Analysis of methylamine uptake by different P. involutus isolates revealed no obvious trend in the uptake capacities in relation to N deposition at the collection site. Kinetic parameters were determined in P. involutus/Betula pendula (Roth.) axenic association and in detached mycorrhizal roots isolated from forest sites. Enhanced methylamine uptake in the presence of the fungal symbiont was demonstrated. Homogeneous V-max values were found for axenic and detached mycorrhizas, whereas K-m values showed greater variations. (C) 1999 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.

Publishing year

1999

Language

English

Pages

355-366

Publication/Series

FEMS Microbiology Ecology

Volume

30

Issue

4

Document type

Journal article

Publisher

Oxford University Press

Topic

  • Biological Sciences

Keywords

  • Ammonium/methylamine uptake
  • Kinetic experiment
  • Mycorrhiza
  • Paxillus involutus

Status

Published

Research group

  • Microbial Ecology

ISBN/ISSN/Other

  • ISSN: 1574-6941