Efeitos de aminoacidos e de peptona sobre o crescimento micelial de Gigaspora gigantea in vitro

Abstract

The vesicular-arbuscular mycorrhizal fungi have attracted great interest, because of their beneficiai effects on the nutrition and growth of crops. However, their obligatory biotrophical charater and the little Information available on their nutrition and physiology have made the multiplication of these fungi difficult in purê culture. This fact has limited the application of these fungi in large scale- agriculture. In the present study, the effects of organic nitrogenous compounds on the in vitro mycelial growth of pré-germinated spores of Gigaspora gjgantea were studied in order to obtain support for the definition of culture media able to sustain their growth and sporulation. The amino acids glycine, histidine, leucine, lysine, phenylalanine, asparagine, arginine, cysteine, cystine, methionine, proline, aspartic acid, glutamic acid and peptone were added individually, in different concentrations, to a liquid médium. The amino acids and concentrations beneficiai mycelial to growth were selected, grouped and tested in several combinations. After 15 days, the morphology of the mycelium was observed under dissecting microscope and the mycelial growth quantified by the hyphal intersection method. The amino acids histidine, cystine and leucine improved the mycelial growth of G. gigantea, while phenylalanine and methionine and peptone inhibited the growth, their effects being dependent on the concentrations used. The grouping of stimulatory amino acids did not result in synergistic effects on the mycelial growth. Morphological alterations of hyphal branching, amount of auxiliary cells formed, and spore color were observed in the presence of some amino acids.