Explore The Bioactive Metabolites From Marine Bacteria Associated With Marine Organisms

In order to explore the marine natural products of medical potentiality and their origin,we carried out the properties analysis of bioactive metabolites from marine bacteriaassociated with marine organisms along the coast of China. Through screening ofantimicrobial and cytotoxic activities, we observed that the percentage of active strainsisolated from marine organisms was higher than that from other sources. In addition,four strains with antiviral (SARS-Cov) activity and seven strains with algaecidalactivity were found among these active marine strains. The 16S rRNA sequences andphylogenetic analysis indicated most strains with bioactivity were belonged to the genesof Pseudoalteromonas sp. and Bacillus sp. The antimicrobial and cytotoxic activities of the metabolites from marine spongeassociated bacterium Pseudoalteromonas sp. NJ6-3-1, and the component of its fattyacids, were either investigated when cultured under different condition. We studied themethod of marine bacteria identification through fatty acids analysis and its feasibilitywas discussed. The results showed that bioactivities of metabolites were influencedunder various cultured conditions, and there was no correlation between bioactivemetabolites yield and bacteria biomass. No change occurred to fatty acid composition,while its content changed obviously under different condition. Hierarchical clusteranalysis indicated that the changes were significant effected by temperature and theamounts of unsaturated and odd fatty acids declined when temperature increased.Identification of marine bacteria through fatty acids composition analysis wasinvestigated and compared with 16S rRNA sequence analysis. The results demonstratedit is feasible to identify marine bacteria to genus level. 3中国科学院海洋研究所博士论文 海洋生物附生细菌活性代谢产物研究 The bacterium Pseudoalteromonas sp. NJ6-3-1 was cultured with 25 L fermentationmedia in 30L continuous stirred tank reactor. Its secondary metabolites were purifiedusing various separation methods and 13 pure compounds were elucidated bycombination of MS and 1D, 2D NMR modern spectrum methods. These compounds arealkaloids, steroid and organic acids and two of them are novel compounds. Additionally,some compounds are first found from the metabolites of marine bacterium associatedwith sponge since they have been found from marine invertebrates. Six compounds areof antimicrobial or cytotoxic activities, especially for norharman with significantactivities. To detect the cytotoxic mechanism of norharman with significant cytotoxicity, weused several measures to confirm the apoptosis effect on Hela cell line. Through AO/EBstain, TUNEL and DNA ladder detection, the phenomenon of DNA damaged andapoptosis induced by norharman were observed. The flow cytometric analysis revealedthe cell treated with norharm for 48h could not enter S phase, and it indicated norharmhad the ability to combine with DNA which cause DNA damaged and the apoptosisoccurred when cell enter S phase. This study was stared with isolation of marine bacteria associated with marineorganisms, continued with bioactive screening, bacteria identification, fatty acidsanalysis, secondary metabolites production, compounds separation and elucidation andapoptosis mechanism investigation of cytotoxic compound. Through these works, theintegrated approach to explore the potential of marine bacteria for the production ofbioactive metabolites was established and some new evidences of the marinemicroorganisms as medical origin were provided.