Isolation,Identification And Secondary Metabolites Of Actinomycetes From Dabancheng Salt Lake,Xinjiang

Halophilic actinomycetes are important sources of secondary metabolites with novel structures and different activities due to their unique physiological characteristics and metabolic mechanism.At present,with the increasing resistance of pathogenic microorganisms,it is difficult to screen lead compounds with novel structure and strong activity in the research and development of existing antibiotics and drugs.Salt lake,as one of the extreme environments where microorganisms come from,has become a research hotspot.In this experiment,the sludge from Dabancheng salt lake in Xinjiang province was collected,and the actinomycetes were isolated and identified.Combined with the antagonistic activity test,the bacterial strains with biological activity were screened out.The secondary metabolites of the active bacterial strains were separated,and their structure and antibacterial and anti-tumor activities were detected.The main results are as follows:（1）From xinjiang urumqi Da Ban Cheng Salt Lake City to collect 15 to 20 cm deep lake silt samples,and natural air at room temperature for 7 to 10 days,adopts the method of plate dilution coated choose four special medium 18 strains of halophilic bacteria was isolated,identified the 18strains morphology combined with molecular biology halophilic bacteria,belonging to 14genera,Bacillus（2 strains）,Pseudoxanthomonas（1 strain）,Rhodococcus（1 strain）,Micromonospora（1 strain）,Streptomyces（2 strains）,Brevibacterium（1 strain）,Tsukamurell（2strains）,Planococcus（1 strain）,Nocardiodes（1 strain）,Metabacillus（1 strain）,Paenibacillus（1strain）,Microbacterium（1 strain）,Micrococcus（1 strain）,Nocardiopsis（2 strains）.There were 12actinomycetes and 10 rare actinomycetes.The most species were isolated from M-7 medium.（2）The antibacterial activity of some actinomycetes was determined by plate confrontation method and anti-tumor activity was determined by SRB method.Streptomyces sp.DBC5 was selected as the target strain for secondary metabolite mining after preliminary screening combined with TLC and analytical high performance liquid chromatography.（3）The strain DBC5 was identified as Streptomyces longispororuber by morphological identification,physiological and biochemical characteristics and molecular identification.Four compounds were isolated and identified from the liquid fermentation product of this strain by using silica gel column chromatography,high performance liquid chromatography,HPLC and other separation and purification methods,as well as high-resolution mass spectrometry,IR infrared spectroscopy,NMR nuclear magnetic resonance and other structural identification techniques.arabomycin（1）,parabens（2）,urdamycinone B（3）,strepolyketide D（4）.（4）The above monomeric compounds were evaluated for their activity,including antibacterial activity and antitumor activity.The results of antibacterial activity showed that compounds 1 and 3 had good anti-Pseudomonas aeruginosa（Gentamicin:MIC value is 3.13μg/m L）.Compounds 1,3,4 showed weak antioxidant activity against Escherichia coli,Staphylococcus aureus,Staphylococcus epidermidis and Candida albicans,and their MIC were all greater than 50μg/m L.The results of cytotoxicity experiments showed that compounds 1 and 3had certain activities on the proliferation of colon cancer cells HCT-116,with IC₅₀of 20.0μM and23.5μM,respectively;compound 1 had a certain effect on the proliferation of lung cancer cells A549 which IC₅₀was 29.6μM.