NEW SOURCES OF CYTOCHALASIN-A AND CYTOCHALASIN-B FROM DEMATIACEOUS HYPHOMYCETES

One hundred isolates of 27 species belonging to 13 genera of dematiace ous hyphomycetes were screened for production of cytochalasins A and B . Most of these isolates (94) were obtained from Assiut University Cul ture Collection, Botany Department, Faculty of Science, Assiut Univers ity, Egypt; three isolates from CBS, The Netherlands; two isolates fro m DSM, Germany; and one isolate from IMI, UK. The results revealed tha t 10 isolates of six species representing five genera of fungi produce d cytochalasins A and/or B. These species are Alternaria chlamydospora , Cochliobolus spicifer, Diplococcum spicatum, Phoma herbarum, Phoma m ultipora and Setosphaeria rostrata. This is the first report for the p roduction of cytochalasins A and/or B by these species of dematiaceous hyphomycetes.