Molecular reidentification of human pathogenic Trichoderma isolates as Trichoderma longibrachiatum and Trichoderma citrinoviride

Several species of the well-known saprophytic genus Trichoderma have been i dentified as the cause of infections in immunosuppressed humans. Because th e differentiation and identification of Trichoderma species based on morpho logical characters only, is very difficult, two molecular approaches were a pplied for species identification. Six human pathogenic Trichoderma isolate s were investigated by PCR-fingerprinting and analysis of ribosomal DNA int ernal transcribed spacer (ITS) sequences and compared with the correspondin g data sets established for described species of the genus. Five of these s trains were identified as T. longibrachiatum, whereas one single strain tur ned out to be T. citrinoviride. Both species are very closely related and b elong to Trichoderma section Longibrachiatum. These data indicate that the occurence of pathogenic Trichoderma strains may be restricted to species of section Longibrachiatum.