RESUMO
AIMS: Compare and characterize Chaetomium strains with special regard to their potentialities as biocontrol agents. METHODS AND RESULTS: Twelve strains of the fungal genus Chaetomium from diverse ecological niches were identified as belonging to six different species. Large differences were observed between the strains with regard to temperature requirements for mycelial growth and pigmentation of culture filtrates. Culture filtrates and ethyl acetate extracts were assayed for fungicidal effects against important phytopathogens both on agar media and in multiwell plates. The samples from Chaetomium globosum were particularly active against Botrytis cinerea, Pyrenophora graminea and Bipolaris sorokiniana, while those from C. cochliodes and C. aureum were inhibitory towards Phytophthora infestans, and P. infestans and Fusarium culmorum respectively. To narrow down the active principle, the most promising extracts were separated by preparative HPLC and the resulting fractions tested in bioassays. Chaetoglobosins were identified as active compounds produced by C. globosum. CONCLUSIONS: The bioassays revealed C. aureum and C. cochliodes as promising candidates for use in biocontrol. Both showed remarkably good activity against the prominent plant pathogen P. infestans. SIGNIFICANCE AND IMPACT OF THE STUDY: We provide the first systematic study comparing six different Chaetomium species with regard to their use as biocontrol agents.