Effect of benomyl and benomyl resistance on cellulase formation by Trichoderma reesei and Trichoderma harzianum

To investigate the possible relationship between resistance to benomyl and the production of cellulases by Trichoderma spp., we investigated the effect of benomyl on growth and cellulase formation in Trichoderma reesei, Trichoderma harzianum, and the benomyl-resistant mutant T. harzianum T95. While T. reesei produced the highest and T. harzianum the lowest cellulase amounts, growth of both strains was equally inhibited by 2 μg/mL benomyl. However, sublethal doses of benomyl (0.2–0.5 μg/mL) promoted growth, stimulated cellulase production, and produced a highly branched, crippled morphology. The same phenomenon was observed with T. harzianum T-95, albeit at higher (5–10 μg/mL) benomyl concentrations. Introduction of the Neurospora crassa ben gene, coding for a benomyl-resistant β-tubulin, into a T. reesei by transformation yielded a series of transformants, which exhibited increased growth, increased cellulase formation, and highly branched, crippled morphology. Key words: Trichoderma harzianum, Trichoderm...