Studies On The Bioactive Metabolites Of Salt-tolerant Actinomycetes From Yellow River Delta

Microbial diversity constitutes an infinite pool of novel chemistry, building a valuable resource for innovative biotechnology. Over 23,000 microbial secondary metabolites have been identified,42% of which are produced by actinobacteria. Out of the approximately 10,000 known antibiotics,45-55% is produced by streptomycetes. The most recent estimates suggest that by now we know only approximately 5% of the total species of fungi and may be as little as 0.1% of the bacteria.The Yellow River Delta is a complex domain shaped under the interaction between the ocean and continent. It is featured with serious salinization, forming a relatively unique ecological environment, suggesting that it may have special biological metabolic pathways in such an environment, which can produce vagarious metabolites. The area exist salt-tolerant microorganisms which can produce novel structure and activity compounds, worth for further study.In order to study the source of the Yellow River Delta salt-tolerant strains of secondary metabolites, we combine chemistry and bioactive screening integration model, as well as tracing the antibiotic component after every separation; a study is carried out to the Yellow River Delta saline soil microorganisms. The main contents are:separation and purification of salt-tolerant microorganisms; screening tolerant actinomycetes and optimization of fermentation conditions; isolation and purification of secondary metabolites from the fermentation products; identification the structure and preliminary evaluation activity of the monomer compound.We obtained 66 salt-tolerant strains, including 19 fungal strains and 47 actinomycetes strains isolated from soil samples of Yellow River Delta. And through integration screening method combining chemistry and activity, two salt-tolerant actinomycetes OUCMDZ-2399 and OUCMDZ-2407 were screened and their secondary metabolites were in further exploration and research.By examining the effects of different culture media, microporous resin, pH and salinity four aspects, on secondary metabolites of the two sale-tolerant fungi, determined a large-scale fermentation conditions. Their secondary metabolites using vacuum and pressure silica gel column chromatography, thin layer chromatography, gel column chromatography and semi-preparative HPLC chromatography and other separation and purification technologies, isolated 9 compounds from fermentation products. Combined with mass spectroscopy and NMR spectroscopy and other methods to identify compounds structures,3 were identified the final (structure shown in Figure 1). All of them are Lobophorins.Using paper disk method and Micro turbid metric method on the part of a preliminary evaluation of compounds antibacterial activity, part of them represent potent antibiotic activity against S. aureus as well as B. subtilis. MTT assay and CCK-8 assay for cytotoxic activity of some compounds of the preliminary evaluation, but none of them shows activity against A-549, K562 or HL-60.In summary, an actinomycete strain was screened by chemistry and active integration model in this paper, and secondary metabolites were in-depth study. At total 9 compounds were isolated and identified, and these compounds were preliminary evaluated by antimicrobial and cytotoxic activity. These results suggest that salt-tolerant actinomycetes are potential to research, worthy of further exploration in depth and systemic.