Showing papers on "Trichoderma longibrachiatum published in 1985"

Phytopathogenic Fusarium oxysporum Schlecht, as a Necrotrophic Mycoparasite

Abstract: Fusarium oxysporum f. sp. dianthi, f. sp. lycopersici, f. sp. cepae, f. sp. niveum and one unidentified F. oxysporum isolate proved to be active necrotrophic mycoparasites. In dual cultures hyphae of Trichoderma hamatum, T. longibrachiatum, T. pseudokoningii, T. harzianum, Botrytis cinerea and Rhizoctonia solani were parasitized and destroyed by F. oxysporum. One isolate of Phytophthora sp. was not affected. Mutual parasitism between F. oxysporum and T. pseudokoningii and T. longibrachiatum has been observed, too. Details of parasitic hyphal interactions: hyphal coiling, penetration sites, resistance sheat formation, hyphal invasion and internal growing are described. The mycoparasitic feature as well as antimicrobial metabolic production of F. oxysporum is probably a common phenomenon to ensure this important plant pathogenic species to compete successfully against other soil-borne fungal pathogens and saprophytes.

Effect of cultural conditions on production of cellulases in Trichoderma longibrachiatum

Abstract: The production of cellulase components which include FP activity, CM-ase and β-glucosidase on carboxymethyl cellulose (CMC) was investigated. The relative distribution of cell free and cell associated enzymes varied with the age of the culture. The optimal pH of the medium for synthesis of enzymes in extracellular, cytosol and cell debris associated states was between 4.5 and 5.0 with optimal temperature being 27 °C. Shake cultures gave comparatively low yields of enzymes as compared to stationary cultures. When the medium was supplemented with 1% lactose, maximum production of cellulolytic activities in the culture fritrate was achieved, that is, 8.1, 0.6 and 0.13 units per ml of CM-ase, FP activity and β-glucosidase respectively. There was a varied response in the induction of cell associated enzymes by different substrates. An increase in substrate concentration (CMC and lactose) had no significant effect on production of extracellular enzymes.

Production, localization and glucose repression of β‐glucosidase in Trichoderma longibrachiatum

Abstract: Optimal production of beta-glucosidase was obtained by incubating the culture at 27 degrees C in a growth medium that had an initial pH of 5.0 and contained cellobiose. The bulk of the enzyme (70%) was present in a cell-associated state (cell debris and cytosol) while only a small portion (30%) appeared in the culture filtrate. When cellulosic substrates were used, the major portion of the enzyme (70%) appeared in the extracellular fraction. A repression of the enzyme occurred in the presence of glucose. A drop of the pH of the medium during the exponential growth phase coincided with a rapid inactivation of the enzyme. The glucose effect was most likely mediated by adverse effects of low pH on the integrity of the enzyme.