Investigation Of Bioactive Metabolites Resources In Antarctic Actinomycetes And Study Of Secondary Metabolites Produced By Two Antarctic Actinomycetes Strains

Actinomycetes are the most economically and biotechnologically valuable prokaryotes. They are responsible for the production of about half of the discovered bioactive secondary metabolites. Because of the excellent track record of actinomycetes in this regard, it is significant that new groups of actinomycetes from unexplored or underexploited habitats be pursued as sources of novel bioactive secondary metabolites. As an important microorganism resource, Antarctica actinomycetes,howerver, have not been researched systematically till now. In this paper, the diversity and novelty of Antarctic actinomycetes have been studied. Antitumor bioactivity was been screening combined with chemical screening. The NRPS, PKS and helogenase genes of actinomycetes have been screening by PCR. The study of secondary metabolites produced by two Antactic actinomycetes strains was carried out to investigate the potential anti-tumor compounds.105 strains were isolated from 18 Antarctic soil samples. After dereplicated by BOX-PCR, there are 67 different strains remained. According to BOX-PCR genomic fingerprinting cluster analysis, 23 strains were selected to be amplified the 16S rDNA sequences. The sequences blast results showed that the 23 strains belong to family Streptomyces,Arthrobacter,Nocardiopsis and Saccharopolyspora respectively. There are 5 strains that the similarities between their 16S rDNA sequences and those of standard strains in the NCBI database are less than 98%. According to phylogenetic analysis, these 5 strains are likely to be novel actinomycetes.By combinatory use of brine shrimp bioassay testing, flow cytometry bioassay against P388 cell line, and chemical analysis, 12 bioactive strains have been screened from 67 strains.The modular Polyketide synthase (PKS), nonribosomal Peptide synthetase (NRPS) and helogenase have been found to be involved in natural Products synthesis in many microorganisms. In this study, the PKS gene, NRPS gene and helogenase gene have been screening. There are 46 strains containing NRPS gene, 39 strains containing PKS gene and 11 strains containing helogenase gene.Monitoring by bioassay-guided isolation, the active fraction is chromato- graphed on silica gel, Sephadex LH-20 and prepared TLC, and preparative reversed phase HPLC, respectively, 17 compounds were isolated from the two active strains. Six compounds (1-6) were isolated from Sreptomyces sp. ZS22-3, eleven compounds (7-17) from Sreptomyces sp. GW25-5.By means of modern spectral analysis (UV, IR, NMR, MS) and physico-chemical properties, the structures (see Fig.1) of seventeen pure compounds were respectively determined. Among them there are three new compounds, which are actinomycin-type compounds(3-5). In addition, the chemical structure types of compounds are mainly involved in cyclic dipeptides (11-17),nucleoside (9,10), Benzene derivates (6,8), etc.The results revealed the novelty and diversity of Anarctic actinomycetes and their secondary metabolites. Antarctic actinomycetes are important resources for bioactive secondary metabolites and they have great value for further study and development.