Activity of native hydrolytic enzymes and their association with the cell wall of three ectomycorrhizal fungi.
The ecological and biogeochemical relevance of hydrolytic enzymes associated with the fungal cell wall has been poorly studied in ectomycorrhizal (ECM) fungi. We used a modified sequential extraction procedure to investigate the activity of various hydrolytic enzymes (β-glucosidase, acid-phosphatase, leucine-aminopeptidase, chitinase, xylanase and glucuronidase) and their association with the cell wall of three ECM fungi (Rhizopogon roseolus, Paxillus involutus and Piloderma croceum). Fungi were grown on C-rich solid medium under three different P concentrations (3.7, 0.37 and 0.037 mM). The sequential extraction procedure classifies enzymes as: (a) cytosolic, (b) loosely bound, (c) hydrophobically bound, (d) ionically bound and (e) covalently bound. Results showed that for the same fungus absolute enzymatic activity was affected by P concentration, whilst enzymatic compartmentalization among the cytosol and the cell wall fractions was not. The association of enzymes with the cell wall was fungus- and enzyme-specific. Our data indicate also that enzymes best known for being either extracellular or cytosolic or both, do act in muro as well. The ecological implications of cell wall-bound enzymes and the potential applications and limitations of sequential extractions are further discussed.
Section of Forest Genetics, Technische Universität München, Hans Carl von Carlowitz Platz 2, 85354, Freising, Germany. perezdemora@gmail.com
Alfredo
A
Pérez-de-Mora
Bianca
B
Reuter
Marianna
M
Lucio
Alfred
A
Ahne
Michael
M
Schloter
Karin
K
Pritsch
D002473:Cell Wall / Q000201:enzymology*; D005591:Chemical Fractionation; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D015966:Gene Expression Regulation, Fungal; D038821:Mycorrhizae / Q000166:cytology* / Q000201:enzymology*
D005656:Fungal Proteins