Secondary metabolite production in diverse marine bacteria from Papua New Guinea

Marine invertebrates are known to produce many structurally diverse secondary metabolites with unique biologically activities. Many of these compounds have pharmacological potential as anticancer, antiviral, anti-infective and antibacterial agents. Many of these marine invertebrates especially marine sponges are filter feeders and host a diversity of microbes, through symbiotic relationships. Since marine invertebrates are sessile and are unable to defend themselves physically, it is hypothesized that symbiont microbes produce chemical defenses to ward of predators. This arises from the fact that many natural products, specifically polyketides and nonribosomal peptides isolated from invertebrates chemically resemble those that are produced by microorganisms. Research shows most microorganisms possess polyketide synthase (PKS) and nonribosomal peptide synthetase (NRPS) biosynthetic genes and therefore have genetic basis to produce those molecules. In this research, bacteria were isolated from marine invertebrates, ocean sediments and marine flora collected in Papua New Guinea. Bacterial isolates from these environments were selected for chemical investigation on the basis of testing positive for NRPS and PKS encoding genes in our PCR based genetic screening. Chemical characterisation of pure compounds was achieved using 1D 1H and 13C NMR and 2D COSY, HSQC and HMBC experiments together with mass spectral analysis. This work has led to the isolation and characterisation of several known peptides, two new indole compounds and a new undecenoic anhydride