Chitin elicitation of natural product production in marine bacteria

Genome sequences reveal that our current standard laboratory conditions only support a fraction of the potential secondary metabolism in bacteria.1 Thus, we must rethink cultivation, detection, and isolation strategies for bacterial secondary metabolites in order to explore the huge, so far uncharacterized chemical potential of these organisms.

As part of a new project on ecology-driven drug discovery at the Technical University of Denmark, we investigate the use of chitin to elicit or alter production of antibacterial compounds in marine bacteria. Within our large collection of Gram-negative bacteria (mainly Pseudoalteromonas and Vibrio), we found that some strains were capable of producing antibacterial compounds when grown on chitin, an N-acetyl-D-glucosamine polymer found in the exoskeleton of zooplankton.2 A strain of Vibrio coralliilyticus solely produced the antibiotic andrimid,3 indicating that andrimid serves a function while growing on chitin-containing surfaces.

In contrast, a Photobacterium halotolerans sustained production of all metabolites including the antibiotic holomycin. Furthermore, chitin stimulated the production of two potentially novel metabolites not observed on glucose-based medium. The different phenotypic responses to a natural growth substrate may reflect different niche-adaptations or ecological functions of the compounds produced and it represents a fruitful approach for elicitation of natural product production in marine bacteria.