Study On Rakicidin B,A Secondary Metabolite Produced By Micromonospora Sp. FIM02-523

Research objectives:1.to screen hereditary stability and high yield of rakicidin B strain2.to optimize the fermentation medium and culture condition3.extraction,isolation,purification and structure identification of the secondary metabolites from strain4.antitumor activities of rakicidin B in vitroResearch method:1.rakicidin B high yield strain was screened by ultraviolet mutagenesis,and then its hereditary stability was investigated by subculture.2.Single factor and orthogonal experiment were used to optimize the fermentation medium and culture conditions.3.Macroporous resins,medium pressure reverse C18 column chromatography,semipreparative HPLC was used to isolate and purify target compound,and UV,IR,MS and NMR was used to identify structure.4.The antitumor activity of rakicidin B was detected by Sulforhodamine B method.Research results:1.The 48# strain with fine hereditary stability was screened by ultraviolet mutagenesis,which titer was increased 32.1% compared to the original strain.2.The optimal fermentation medium and culture conditions was determined by single factor and orthogonal experiment:soluble starch 6%,sucrose 2%,soybean peptone 2%,Liuhua yeast powder 1%,Ca CO3 0.1%,Mg SO4 0.05%,the fermentation period is 88 h,volume 100 m L,speed 220 rpm,inoculum 5%,defoaming agent 0.3%.3.One compound was get through macroporous resins,medium pressure reverse C18 column chromatography,semi-preparative HPLC,which was identified to the lipopeptide antibiotic rakicidin B reported in literature by UV,IR,MS and NMR.4.The proliferation inhibition activity of rakicidin B on HCT-8,MGC803,A549,A375 and Hep G2 was excellent,and its proliferation inhibition activity under hypoxia condition was 13.88 times higher than that under normoxia condition.Conclusions1.In this study,the 48# strain with great hereditary stability and high yield was screened,and the optimal fermentation medium and culture conditions were determined.The fermentation titer has reached 445.4mg/L and realized the level of industrialization2.rakicidin B has showed strong anti hypoxic tumor cell activities,which has great prospect to be a lead compound of anti hypoxic tumor cells.