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The effects of organic and inorganic phosphorus concentration on the acid phosphatase activity of ectomycorrhizal fungi

1988; Canadian Science Publishing; Volume: 66; Issue: 4 Linguagem: Inglês

10.1139/b88-111

1480-3305

Carolyn J. Kroehler, Robert K. Antibus, Arthur E. Linkins,

Fungal Biology and Applications

Kinetic constants (K m and V max ) were determined for surface and extracellular soluble acid phosphatases produced by two ectomycorrhizal fungi (Cenococcum geophilum Fr. and Entoloma sericeum (Bull, ex Merat) Quel.) grown in axenic culture at 2 or 50 μM KH 2 PO 4 or sodium inositol hexaphosphate. Results for cultures supplied inorganic phosphorus were similar to those supplied organic phosphorus: surface V max estimates were significantly greater for 2 than for 50 μM grown isolates. The presence of constitutive extracellular soluble phosphatase activity resulted in the appearance of inorganic phosphate in media initially supplied with organic phosphorus, suggesting substrate hydrolysis in excess of phosphate uptake. No consistent relationship was found between apparent K m estimates and phosphorus treatments. The two species had surface phosphatase V max values differing by as much as two orders of magnitude. The magnitude of the response to phosphorus treatment differed among isolates. The response of phosphatases to changes in phosphorus at concentrations comparable with soil solution phosphorus supports the hypothesis that levels of available soil phosphorus may control ectomycorrhizal phosphatase production or activation.