ABSTRACT
Onychomycosis--the dermatophytic invasion of the nail--is difficult to eradicate with drug treatment. The hyphae of the main invading pathogen, Trichophyton rubrum, are often interwoven with the nail plate, preventing effective anti-mycotic agents from reaching its growing tips. An alternative approach to treat onychomycosis may possibly be the application of a biological control agent against the pathogen. In analogy with the success of biocontrol of phytopathogenic fungi, we screened a series of commercially available Trichoderma strains for potential antagonism between Trichoderma and Trichophyton spp. A wide spectrum of antagonism capacity, ranging from effective overgrowth to no interaction was found, with Trichoderma virens NRRL 26672 being the most effective against the Trichophyton strains tested e.g. T. rubrum NCPF118. Furthermore, T. virens NRRL 26672 grown with T. rubrum NCPF118 hyphae as a carbon source, exhibited enhanced induced secretion of active extracellular chitinases and beta-glucosidases, affecting lysis and sporulation on T. rubrum NCPF118 hyphae. Growth of Trichod. virens NRRL 26672 in poor medium also resulted in secretion of antibiotics active in arresting the growth of T. rubrum NCPF118 inoculum. Our findings may open new directions for the treatment of onychomycosis, either in combination with known medications or as a new "natural" route.
Subject(s)
Antibiosis , Onychomycosis/therapy , Pest Control, Biological , Trichoderma/growth & development , Trichophyton/growth & development , Cellulase/metabolism , Chitinases/metabolism , Culture Media , Humans , Trichoderma/enzymology , Trichophyton/pathogenicityABSTRACT
A rapid and convenient method for the detection of chitinases accumulating in filamentous fungal cultures was developed. The assay is performed on cultures growing in microtiter plates, with a fluorogenic substrate: 4-methylumbelliferyl-N-acetyl-D-glucosaminide (4-MeUNAG). The fluorescence of the product, 4-methylumbelliferone, was detected. This method was successfully used to follow induction and repression of extracellular exochitinase activity in the biocontrol fungus Trichoderma harzianum.
Subject(s)
Acetylglucosaminidase/metabolism , Trichoderma/enzymology , Trichoderma/growth & development , Culture Media , Fluorometry/methods , Hymecromone/metabolism , Sensitivity and SpecificityABSTRACT
Negatively charged large unilamellar vesicles (LUV) were incubated with tobacco (Nicotiana tabacum var. xanthi) cell suspensions and with the cell-free medium of the cell suspensions. The extent of cell-LUV interaction was determined by the leakage of the LUV contents. Cells enhanced the leakage of LUV contents and this effect increased with cell age. Addition of polylysine to the reaction mixture increased even further the leakage of the LUV contents. The cell-free medium of the cell suspension also affected the integrity of the LUV. Cell-free medium, by itself, promoted leakage of LUV contents and caused a reduction in the leakage exerted by polylysine. Centrifugation (8000g) of the cell-free medium decreased its effect, heat treatment (122°C) did not alter its effect and sonication enhanced it. The effects of the cell-free medium are attributed to the presence of cell wall debris of disintegrated cells.
