Studies on Tricellulortus pepoformis, a tropical mitosporic fungus

Tricellulortus pepoformis is an uncommon tropical mitosporic fungus, which was first described by Matsushima (1995) from leaf litter collected in Japa n. The fungus is characterized by conidia of striking pumpkin-like morpholo gy, bearing three (rarely four) conical protuberances produced from three a djacent conidiogenous cells. However, nothing is known about its phylogenet ic affinities. Recently, while surveying tropical leaf-litter fungi as pote ntial producers of bioactive natural products, we isolated this fungus from leaf-litter collected in Barbados. The isolate produced antifungal activit y against Candida albicans, C. tropicalis. Aspergillus fumigatus and Crypto coccus neoformans, and a weak antibacterial activity against Bacillus subti lis. This activity seems to be due to an unstable polyacetylene. as inferre d from the UV spectrum of the active fractions, recovered after separation of the fungal extract by countercurrent chromatography. Polyacetylenes are widespread compounds throughout the basidiomycetes. Genomic DNA was extract ed from the isolate. and the D1-D2 region of the 28S rRNA gene, as well as the ITS1-5.8S-ITS2 region, were sequenced. Although a comparison of these s equences with the GenBank database failed to find any sequence with suffici ently high similarity to classify this: fungus at the species or even genus level, it unequivocally suggested that the sequence is that of a basidiomy cete. The closest sequences found were those of Multiclavula corynoides and Multiclavula vernalis. which showed about 93% similarity in the D1-D2 regi on.