Discovery of Novel Secondary Metabolites from Fungi—is It Really a Random Walk Through a Random Forest?

Twenty-nine Nodulisporium strains isolated from material obtained worldwide were found to produce secondary metabolites as measured by HPLC. Analysis of incubation conditions resulted in the clustering of three solid fermentation conditions and the clustering of five liquid fermentation conditions. Coverage of 69% of the products produced under eight fermentation conditions could be accomplished if one medium from each cluster was used. Subdivision of the Nodulisporium strains into groups based upon morphological similarity allows for a minimization of the rediscovery of common metabolites. Rare metabolites (HPLC peaks) appeared to occur as random events. However, within the set of cultures that produced the mean or greater than the mean number of metabolites, were found all of the producers of rarer metabolites. Key words: Nodulisporium, fermentation screening, endophytes.