Study And Ribosome Engineering Alteration Of The Secondary Metabolites Produced By A Mangrove Streptomyces Albogriseolus Strain MGR072

As the terrestrial sources have been fully researched, the possibility has become declined gradually that found new species and new secondary metabolites. Thus, people pay attention to the study of new groups from marine and plant endophytes. The microorganisms with special ecological environment can produce numerous metabolites with novel skeletons and varied and unique bioactivities. They have been a very important source for searching new bioactive natural product.In this thesis, secondary metabolites from one Mangrove actinomycete were observed for the discovery of new bioactive compounds.Streptomyces albogriseolus MGR072 was isolated from the sediment collected in Zhangjiangkou Mangrove Natural Reserve Area, Fujian province. The strain was cultivated in ISP3 medium and the fermentation broth was extracted by organic solvent. Alkaloids in the fractionated extractions were tracked by dragendorff reagent and separated by chromatographic method. 2,2-dimethyl-1,3-dihydroquinazolin-4(1H) -one (1) ;Methyl-1,4-dihydro-4-oxoquinoline-2-carboxylate (2) and 1-N-methyl-3 -methylamino-[N-butanoic acid-3′-(9′-methyl-8′-propen-7′-one)-amide]-benzo[f][1,7] Naphthyridine-2-one (4) were identified by NMR and MS, in addition, we also get plenty of chemical information but structure from other alkaloids separated from the secondary metabolites.Ribosome engineering is an efficient approach to develop mutant strains that overproduce secondary metabolites by screening various drug-resistance mutations. In this research spontaneous streptomycin and rifamycin resistant mutants were developed to stimulate secondary metabolism in the strain, guided by special UV absorptions of compound 4, compound 5 and compound 7. The differences in the HPLC fingerprints of the wild-type and the mutant strains showed the changes of metabolic profiles and suggested the accumulation of secondary metabolites by ribosome engineering.Our results indicated that marine microorganisms and plant endophytes can produce novel metabolites. They are important sources of searching leader compounds for drug discovery.