Response of Wolfiporia cocos to iron availability: alterations in growth, expression of cellular proteins, Fe3+-reducing activity and Fe3+-chelators production.
OBJECTIVE
The main objective of this study was to evaluate the behaviour of the brown-rot fungus Wolfiporia cocos under differential iron availability.


RESULTS
W. cocos was grown under three differential iron conditions. Growth, catecholate and hydroxamate production, and mycelial and extracellular Fe3+-reducing activities were determined. Iron starvation slowed fungal growth and accelerated pH decline. Some mycelial proteins of low molecular weight were repressed under iron restriction, whereas others of high molecular weight showed positive iron regulation. Mycelial ferrireductase activity decreased as culture aged, while Fe3+-reducing activity of low molecular reductants constantly increased. Hydroxamates production suffered only limited iron repression, whereas catecholates production showed to be more iron repressible.


CONCLUSIONS
W. cocos seems to possess more than one type of iron acquisition mechanism; one involving secretion of organic acids and ferrireductases and/or extracellular reductants, and another relying on secretion of catecholates and hydroxamates chelators.


CONCLUSIONS
This paper is the first to report the kinetic study of brown-rot fungus grown under differential iron availability, and the information provided here contributes to address more traditional problems in protecting wood from brown decay, and also makes a contribution in the general area of the physiology of brown-rot fungi.
Arantes
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V
Department of Biotechnology, Escola de Engenharia de Lorena, University of São Paulo - USP Lorena, Lorena/SP, Brazil. arantes@debiq.eel.usp.br
Milagres
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AM
D004591:Electrophoresis, Polyacrylamide Gel; D038181:FMN Reductase / Q000378:metabolism; D005656:Fungal Proteins / Q000378:metabolism*; D007218:Industrial Microbiology; D007501:Iron / Q000378:metabolism* / Q000494:pharmacology; D007502:Iron Chelating Agents / Q000378:metabolism; D009172:Mycology; D010935:Plant Diseases / Q000382:microbiology*; D020072:Polyporales / Q000254:growth & development / Q000378:metabolism*; D016622:Silver Staining; D014934:Wood
D005656:Fungal Proteins; D007502:Iron Chelating Agents; D007501:Iron; D038181:FMN Reductase; C023903:ferric citrate iron reductase