Identification Of Alkali-resistant Filamentous Strain XJ-16 And Analysis Of Its Bioactive Components

Actinomycesbovis a kind of important resource microorganism closely related to human production and life,and is one of the main sources of natural antibiotics.Actinomycetes,especially in extreme environments,having special physiological characteristics and metabolic mechanisms,can produce special secondary metabolites,and are an important source for finding new natural antibiotics.In this study,a new filamentous bacteria strain with high antibacterial activity isolated from saline-alkali soil in Xinjiang was used as the starting strain.Based on the classification and attribution,the biological activity,fermentation conditions,separation and purification of antibacterial substances and other aspects were investigated,which laid a foundation for further development and utilization of the strain.The main results of this paper are as follows:(1)Morphological observation,physiological and biochemical tests and molecular identification tests show that the starting strain belongs to the blue group of Streptomyces of Actinomycetes and is named strain XJ-16.XJ-16 is not resistant to temperature and halophilic.It has certain alkalophilic characteristics.Enzyme spectrum analysis showed that XJ-16 can secrete cellulase,lipase,urease,protease,catalase and lipase.(2)The bacteriostatic experiment of the fermentation broth showed that the fermentation broth of XJ-16 had strong bacteriostatic activity against 5 pathogenic bacteria indicator bacteria except for the S type of Klebsiella pneumoniae.Except for the inhibitory effect on pseudofilamentous yeast fungus Candida albicans,it has no inhibitory activity on 5 pathogenic fungi indicator bacteria.The secondary metabolites of XJ-16 fermentation broth have different tolerance to acid and alkali,strong and stable tolerance to acid,alkaline conditions and reduced activity.Sensitive to temperature and ultraviolet light,easy to deactivate.(3)The optimization of bacteriostatic activity medium showed that XJ-16 had the strongest bacteriostatic activity with the best medium composition as follows: soluble starch 2 g,potassium nitrate 0.1 g,sodium chloride 0.05 g,dipotassium hydrogen phosphate trihydrate 0.05 g,magnesium sulfate 0.05 g,distilled water 100 mL,pH 5,fermentation conditions were 1% inoculum size,culture temperature 28?,180 r/min,fermentation time 10 days.Under the optimized conditions,the bacteriostatic rate of the fermentation broth of the strain against indicator bacteria reached 65.48%,with the strongest bacteriostatic activity.(4)The organic matter extraction experiment shows that the best extractant is ethyl acetate.PH paper chromatography was used to preliminarily identify antibiotic species of antibacterial substance,which is alkaline antibiotic.Thin layer chromatography,silica gel column chromatography,microplate reader,semipreparative HPLC,HPLC and other separation technologies were adopted to further purify a substance,which showed that the ratio of methanol to water in mobile phase was 80%: 20%,the detection wavelength was 280 nm,and the retention time on HPLC was 13.261 min.