Chemical Diversity of Metabolites and Antibacterial Potential of Actinomycetes Associated with Marine Invertebrates from Intertidal Regions of Daya Bay and Nansha Islands

Abstract

Marine actinobacteria particularly from marine environments are believed to be inexhaustible sources of biologically active molecules for biomedical and industrial applications. We isolated 126 strains of marine actinomycetes from marine invertebrates such as corals, sponges and gastropod molluscs from Daya Bay and Nansha Islands. The chemical diversity of the metabolites from the isolated strains was evaluated using HPLC-UV fingerprinting and their antibacterial activity was estimated. Preliminary chemical screening and antibacterial activity clearly illustrate that the marine invertebrates-associated actinomycetes are a rich source of novel biologically active compounds. Among the isolates, strain SCSIO-PTE-L054 was further investigated for its unique metabolic profile and antibacterial activity. The bioassay-guided isolation rendered a polycyclic tetramate macrolactam (PTM) as a major chemical constituent with potent antibacterial activity. Our results revealed that the Streptomyces sp., strain SCSIO-L054 is a new source of PTMs which could pave a way to isolation of new series of PTMs with a broad spectrum of activity. In summary, the present investigation makes it possible to select marine actinomycetes from Daya Bay and Nansha Islands as new potential sources to produce potent compounds for a wide range of applications in future drug discovery.