Among 85 fungal taxa previously isolated from the marine sponge Psammocinia sp., approximately 10% were identified as Aspergillus spp. Strains OY207 and OY907 secreted metabolites that inhibited growth of several fungi (Alternaria alternata, Rhizoctonia solani, Neurospora crassa). The strains were identified, on the basis of partial ITS and beta-tubulin sequences as A. tubingensis and A. insuetus, respectively. To determine the nature of the inhibitory effects imposed by the secreted compound(s), we generated random tagged N. crassa mutants resistant to the Aspergillus spp. medium extracts. Plasmid rescue analysis of one of the mutants indicated that a defect in a yet-uncharacterized gene (NCU03140.4), designated rat-1, confers resistance to the A. tubingensis extract. This was confirmed by analysis of the appropriate knock-out strain and rat-1 complementation. RAT1::GFP expression indicates it is localized to hyphal septa, suggesting that the toxic compound may function in association with septal proteins/structures. Current analysis indicates that the two Aspergillus spp. secret novel terpenoids and polyketides, whose structures and antifungal properties are being assessed.
Full conference title:
26th Fungal Genetics Conference
- Fungal Genetics Conference 26th (2005)