Abstract: The antibacterial and anti-quorum sensing activities of 84 actinomycetes isolated from mangrove sediment against the indicator bacteria, Chromobactierium violaceum, Escherichia coli and Staphylococcus aureus, were tested by disc diffusion assay. The highly active strains were selected for secondary activity screen and chemical diversity analysis by thin layer chromatography. The results showed that strain HN2-56 had strong anti-quorum sensing activity and weak antibacterial activity, and its metabolites were abundant. The secondary metabolites of this strain were preliminary isolated and analyzed by GC-MS. 13 possible compounds were identified and many of them had certain biological activity. The activity verification results showed that compounds 4 (diethyl toluamide) and 12 (curcumenol) had anti-quorum sensing activity. Through 16S rDNA sequence analysis, morphology observation and phylogenetic analysis, the strain HN2-56 was identified as Streptomyces chumphonesis. This strain has certain application potential in anti-quorum sensing and has the value of further study.

Key words: actinomycetes, antibacterial activity, anti-quorum sensing activity, GC-MS