| Coral reef ecosystem is the highest diversity one in many marine ecosystems, inwhich live almost all marine organisms. Along with the deep development of marinenature products and marine drugs, marine symbiotic and epiphyte microorganismsespecially which derived from tropical coral reef invertebrate induce more attention.In present paper, diversity and antimicrobial activities of gorgonian-derived symbioticmicroorganisms, antimicrobial action and action mechanism of secondary metabolitesproduced by active strains have been investigated preliminary.1. Study on diversity and antimicrobial activities of gorgonian-derived symbioticmicroorganisms from South China Sea. Ten gorgonian from the Weizhou coral reef inthe South China Sea have been chosen for chemical investigation.242fungus and84bacteria have been separated. Combined with, ITS-rDNA sequences revealed18fungal strains from this gorgonian. Partial fungus and bacteria are indentifiedcombined with morphologic traits, physiological and biochemical characteristics andmolecular biological method. In addition, phylogenetic trees of ten gorgonian havebeen builted. As for the fungus quantity derived from gorgonian, there are44fungusderived from Anthogorgia ocbracea which has the most ones and12fungus derivedfrom Junceella juncea which has the less ones. As for the fungus diversity,13identified fungus derived from Paraplexaura sp. belong to eight genera in six orderswhich is the highest diversity of the ten gorgonian.7indentified fungus of J. junceabelong to four genera in three orders which is the lowest diversity. As for theoccurrence frequency of deferent fungus, Penicillium sp., Cladosporium sp. andAspergillus sp. are the highest occurence frequency genera. Aureobasidium sp., Pichiasp. and Bullera sp. are lowest occurence frequency, which are only derived from several special gorgonian. The antibacterial activity results of gorgonian-derivedfungus have indicated that most of these fungus have the antibacterial activity and theantibacterial activity to Gram-positive S．aureus and M．tetragenus are stronger thanto other microorganisms.2. Bioactivity-guided isolation of antibacterial compounds fromgorgonian-derived fungus Alternaria sp. and preliminary study on its mechanismof.Under bioassay guidance, the EtOAc extract of the broth of fungus Alternaria sp.derived from gorgonian Echinogorgia rebekka collected from the South China Seawas separated by column chromatography on silica gel and, Sephadex LH-20,together with semi-preparative HPLC, resulting in the isolation of macrosporin, ananthraquinone with antibacterial activity against marine pathogenic and microfoulingbacterium Vibrio anguillarum. Its structure was identified with spectroscopic analysisof NMR and MS by comparing with the data in literature. The antimicrobialmechanism of macrosporin against V. anguillarum was studied. It was found thatmacrosporin killed the bacteria by destructing the cell wall and cytoplasmicmembrane, leading to the increase of cell permeability, lysising genomic DNA, thusresulting in the extravasation of cell content. This is the first report on the antibacterialactivity and antimicrobial mechanism of macrosporen against marine bacterium V.anguillarum.In conclusion, in present study the diversity and evolutional relationship ofgorgonian-derived symbiotic microorganism from South China Sea have been studiedfor the first time together with phylogenetic trees of10gorgonian-derived fungushave been built; This is the first report on the antimicrobial mechanism against V.anguillarum from cell permeability, Ultramicro-cell structure and cell DNA ofmacrosporen isolated from fungus Alternaria sp. derived from gorgonian. All theseresults provide precious resources for research and development of marine naturalproducts and marine drugs and lay a foundation for the further studies onantimicrobial activity mechanism. |
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