Tyrocidine a from a haliclona sponge derived Vibrio sp

Taxonomically diverse, sponge-associated microbial communities represent a rich source of potentially novel and bioactive natural products. In our search for bioactive compounds from sponge-associated microbes we isolated and identified a Vibrio sp. from a sample of Haliclona collected from Milne Bay, Papua New Guinea. The Vibrio strain was selected for further investigation on the basis of testing positive for the presence of non-ribosomal peptide synthetase (NRPS) coding genes in our PCR-based screen.

Chemical investigation of this Vibrio sp. resulted in the isolation and identification of the NRPS product tyrocidine A, and its decapeptide structure was confirmed by 1D and 2D NMR. Tyrocidine A displayed moderate activity against methicillin resistant S. aureus, E. coli and P. aeruginosa.

The discovery of tyrocidine A from a marine Vibrio sp is intriguing from a microbiological viewpoint as it has long been known to be a product of the Gram-positive, soil-dwelling and spore forming Bacillus spp. Aspects of this, and the notion that the marine environment is a largely untapped source of bioactive natural products will be presented.