The Screening For Antibacterial Actinomycetes Associated With Marine Sponges And The Isolatiob And Identification Of Metabolites From Strain Hvg 29

Due to the peculiar living environment, marine derived actinomycetes has evolved the complex and special metabolic pathway. The secondary metabolites produced by marine actinomycetes display wide diversity and distinction in chemical structures, as well as biological activity,compared with that of terrestrial actinomycetes. Exploration of marine actinomycetes to search out active lead-compounds for new drugs has become a focus of research.Marine sponges are the most primitive metazoans. As filter feeders, their biomass can consist of a large number of microorganisms. Therefore, it is an efficient way to obtain marine derived actinomycetes from marine sponges.In this paper,101 actinomycetes isolated from marine sponges which are Hymeniacidon perlevis,Reniochalina sp. in Yellow Sea and Craniella australiensis,Stelletta tenuis Lindgren,Halichondria rugosa Ridley&Dendy,Axinella sp. in South China sea were screened for antibacterial activity against three plant pathogenic microorganisms which are Erwinia carotovora,Xanthomonas campestris and Xanthomonas oryzae. The result of the bioactive test showed that about 40% of the strains exhibited antibacterial activity against one or more than one of three indicator organisms.28 strains displayed antibacterial activity against Erwinia carotovora,29 strains displayed antibacterial activity against Xanthomonas campestris and 32 strains displayed antibacterial activity against Xanthomonas oryzae; 30 strains(30%) exhibited antibacterial activity against two or more than two of three indicator organisms and 19 strains (19%) exhibited antibacterial activity against all of three indicator organisms. We identified the strain HVG 29 which has the best antibacterial activity by 16S rDNA analysis. It showed that the strain HVG 29 was Streptomyces sp..Streptomyces sp. HVG 29 was fermented extensively in a liquid state medium for three times. About 45 L product was obtained from fermentation, from which the supernatant and mycelium was extracted respectively, and it worked out about 17 g crude extract of metabolites. The crude extract was separated by silica gel chromatography,thin layer chromatograph,Sephadex LH-20 chromatography,preparative thin layer chromatography, and 3 monomeric compounds were obtained, which were HVG 29-1 (7.8 mg),HVG 29-2(5.3 mg),HVG 29-5(5.9 mg). The structure of these monomeric compounds were determined on the basis of EI-MS,HRESI-MS,1N MMR,13C NMR,DEPT,H-H COSY,HSQC,HMBC, which were 3-Methylthymidine (HVG 29-1),3-methyl-3'-deoxyuridine (HVG 29-5) and 3-acetylthymidine (HVG 29-2), respectively. These compounds all belong to nucleoside analogs, and in addition the HVG 29-2 is a new compound.