Nitrogen nutrition and isotopic discrimination in tropical ectomycorrhizal fungi

• Published in: Research in microbiology Vol. 156; no. 2; pp. 184 - 190
• Main Authors: Brearley, Francis Q., Scholes, Julie D., Su See, Lee
• Format: Journal Article
• Language: English
• Published: Paris Elsevier SAS 01.03.2005; Elsevier
• Subjects: Acacia - growth & development; Acacia - microbiology; Basidiomycota - growth & development; Biological and medical sciences; Biomass; Bovine serum albumen; Culture Media; Fundamental and applied biological sciences. Psychology; Growth, nutrition, metabolism, transports, enzymes. Molecular biology; In vitro growth; Microbiology; Mycology; Mycorrhizae - growth & development; Nitrogen - metabolism; Nitrogen isotope discrimination; Nitrogen Isotopes - metabolism; Pisolithus; Pisolithus albus; Thelephora; Thelephora terrestris; Tomentella; Tropical Climate; δ15N; δ 15N; In vitro growth; Bovine serum albumen; Tomentella; Nitrogen isotope discrimination; Pisolithus; Thelephora; Growth; Basidiomycetes; Fungi; Ectomycorrhiza; Serum; δ15N; Ungulata; Thallophyta; Vegetals; Statistical analysis; Bovine; Nutrition; Albumin; Nitrogen; Vertebrata; Mammalia; Mycorrhiza; Artiodactyla; Veterinary
• ISSN: 0923-2508; 1769-7123
• DOI: 10.1016/j.resmic.2004.09.003

It is known that many ectomycorrhizal (EcM) fungi are able to utilise complex organic sources of nitrogen. Two hypotheses were tested using isolates of tropical EcM fungi grown in vitro: (i) EcM fungi isolated from mineral soils of tropical rain forests are less able to utilise organic sources of nitrogen than mineral sources; and (ii) nitrogen isotope discrimination patterns follow those of the nitrogen source utilised. Pisolithus albus and Tomentella sp. represented tropical EcM fungi and they were grown along with Thelephora terrestris. All three species were able to utilise bovine serum albumen as a nitrogen source and P. albus produced the greatest biomass on this source of nitrogen. Nitrate was generally less well utilised than ammonium although all three species were able to grow on this nitrogen source. The nitrogen source which led to the greatest biomass also led to the highest fungal nitrogen concentration in P. albus and Tomentella sp., but not T. terrestris. All three species discriminated against 15N when grown on BSA and NO 3 but there were interspecific differences in isotope discrimination when grown on NH 4. From a limited number of isolates, it was found that EcM fungi from tropical soils utilise protein nitrogen as well as mineral nitrogen and there can be considerable nitrogen isotope discrimination during the utilisation of all these nitrogen sources.