Inhibitory Effect and Mechanism of Trichoderma taxi and Its Metabolite on Trichophyton mentagrophyte

Trichophyton mentagrophytes is an important zoonotic dermatophyte, which seriously harms the skin of humans and animals. Chemical drugs are generally used for the prevention and treatment of the disease caused by T. mentagrophytes. Discovering new compounds from natural products is an important approach for new drug development. Trichoderma includes a variety of fungal species used for biological control of phytopathogenic fungi. However, the antifungal effects of Trichoderma and their metabolites on zoonotic fungal pathogens are largely unknown. Here, the effect of trichodermin, a metabolite derived from the plant endophytic fungus Trichoderma taxi, on T. mentagrophytes was examined, and the underlying mechanism was explored. T. mentagrophytes growth was suppressed significantly by trichodermin and completely inhibited under 1000 μg/mL trichodermin. The production and germination of T. mentagrophytes spores were remarkably reduced upon exposure to trichodermin, in comparison with control samples. Treatment of lesions caused by T. mentagrophytes on the rabbit skin with 1 mg/mL trichodermin prompted the healing process significantly; however, 20 mg/mL trichodermin was likely toxic to the skin. Under trichodermin treatment, the number of mitochondria in T. mentagrophytes increased significantly, while a few mitochondria-related genes decreased, indicating possible mitochondrial damage. In transcriptome analysis, the GO terms enriched by DEGs in the trichodermin-treated group included carbohydrate metabolic process, integral component of membrane, intrinsic component of membrane, and carbohydrate binding, while the enriched KEGG pathways comprised biosynthesis of secondary metabolites, glycolysis/gluconeogenesis, and carbon metabolism. By comparing the wild type and a gene deletion strain of T. mentagrophytes, we found that CDR1, an ABC transporter encoding gene, was involved in T. mentagrophytes sensitivity to trichodermin.