Competitive Saprophytic Ability and Cellulolytic Activity of Rhizosphere-Competent Mutants ofTrichoderma harzianum

Abstract

Competitive saprophytic ability (CSA) of strains of Trichoderma spp. was determined by the modified Cambridge method (sensu Garrett). Two rhizosphere-competent mutants of T. harzianum (T-95 and T-12B) had higher CSA indices than four rhizosphere-incompetent Trichoderma spp. and strains. CSA was directly correlated with rhizosphere competence (RC). When the strains were grown for 6 days on Czapek-Dox broth with cellobiose, carboxymethyl cellulose, or cotton linters as sole sources of carbon, mutants produced more cellulase than the wild types. The amount of cellulase produced by these strains was directly correlated with CSA and RC. RC of the mutants, therefore, can be at least partially explained by their capacity to utilize cellulose substrates associated with the root.