Mixed fermentation for natural product drug discovery

Natural products continue to play a major role in drug discovery and development. However, chemical redundancy is an ongoing problem. Genomic studies indicate that certain groups of bacteria and fungi have dozens of secondary metabolite pathways that are not expressed under standard laboratory growth conditions. One approach to more fully access the metabolic potential of cultivatable microbes is mixed fermentation, where the presence of neighboring microbes may induce secondary metabolite synthesis. Research to date indicates that mixed fermentation can result in increased antibiotic activity in crude extracts, increased yields of previously described metabolites, increased yields of previously undetected metabolites, analogues of known metabolites resulting from combined pathways and, importantly, induction of previously unexpressed pathways for bioactive constituents.