Mycelial growth of pre-germinated spores of the endomycorrhizal fungus Gigaspora gigantea in liquid medium supplemented with nitrogenous organic compounds

Abstract

The effects of 14 nitrogenous compounds on mycelial growth of G. gigantea spores were evaluated in a liquid medium. Spores were pre-germinated in water-agar and transferred to glass tubes with nutrient liquid medium containing one of the following compounds: glycine, histidine, leucine, lysine, phenylalanine, asparagine, arginine, cysteine, methionine, cystine, proline, aspartic acid, glutamic acid and peptone. Each compound was added individually to the nutrient basic medium at three different concentrations. Tubes with spores were incubated at 25-28°C for 15 days when mycelial growth was evaluated by grid intersection method. The amino acids histidine, cysteine and leucine and peptone stimulated fungal growth, while phenylalanine and methionine showed significant growth inhibition. Growth enhancements were linear for histidine, and square-root model for leucine, cystine and peptone. Methionine showed linear inhibition, while phenylalanine exhibited quadratic response. All the other compounds tested showed no significant effect on mycelial growth.