| Fungi are known to produce a wide variety of secondary metabolites with biological activities that are commercially used as pharmaceutical agents (e.g. lovastatin and penicillin). Genome sequencing has revealed the presence of muted gene clusters that could encode novel secondary metabolites of clinical relevance. Most secondary metabolites are not produced by fungi under the standard laboratory growth conditions. A vast majority of them are produced in very small quantities and often times are masked by known metabolites that are synthesized in much larger quantities. Several approaches have been employed to activate the cryptic clusters to unmask hidden previously undiscovered secondary metabolites. Genetic techniques to explore the secondary metabolome of the Aspergillus species have resulted in the discovery of novel compounds. In our studies, we used chromatography instruments such as liquid chromatography-mass spectrometry (LC-MS), high pressure liquid chromatography (HPLC), and nuclear magnetic resonance (NMR) have assisted in isolation, purification, and characterization of these predicted secondary metabolites. Our methodologies have shown that these instruments are invaluable for the examinations of secondary metabolites and their production in fungi and bacteria. |
