Many bioactive small molecules were originally identified by screening extracts from microorganisms. These so-called natural products, some possessing medicinal value, then became the targets of structure determination and total synthesis. Traditional production methods depended on being able to pinpoint the source of the metabolite and to cultivate high-yielding strains of the isolated organism, but molecular biological advances have made it feasible to look directly for the genetic components of the biosynthetic pathways.
Piel et al. have extracted from the marine sponge Theonella swinhoei the gene clusters encoding the enzymes that make the polyketide onnamide A. Analysis of the gene structure indicates that their true source is probably an as-yet-unidentified bacterial symbiont, possibly of the Pseudomonas genus, harbored by the sponge. -- GJC
Proc. Natl. Acad. Sci. U.S.A. 101, 16222 (2004).
