Study On Separation Of Daptomycin From S.roseosporus Fermentation Broth And Process Optimization

Daptomycin is a new antibiotic drug which is widely used to treat Gram positive bacteria infection symptoms.Main production method of daptomycin is microbial fermentation,and the fermentation broth is complex and it is difficult to separate and purify daptomycin.Therefore,the R&D of cost-effective separation methods has important economic and social benefits.In this thesis,the separation and purification of daptomycin with hollow fiber membranes and ion exchange resins were studies and the separation process was optimized.Main results are summarized as following:(1)The effect of four kinds of hollow fiber membranes on the treatment of daptomycin fermentation broth was investigated.It was found that the hollow fiber membrane of 30 KD was most suitable for the treatment of daptomycin fermentation broth.High clarity and good color removement from the daptomycin fermentation broth could be obtained after two-step pretreatment,and the yield of pretreatment was 88.1%.(2)Six weakly basic anion exchange resins and two strong basic anion exchange resins1 were investigated.The adsorption and elution properties of daptomycin were determined.It was found that the weak alkaline epoxy ion exchange resins 331 and 335 showed good adsorption properties.The former has better elution property and higher recovery of daptomycin could be obtained.After further purification by macroporous resin,daptomycin with high mass percentage purity of 96%was obtained.(3)For static adsorption of daptomycin with the weak alkaline epoxy ion exchange resin 331,the optimum adsorption time was 10 h,and the saturated adsorption capacity was 1.10 mg/mL.The optimum elution flow volume was 2 mL/mL resin,and the highest elution rate was 93.3%.(4)For dynamic adsorption of daptomycin with the weak alkaline epoxy ion exchange resin 331,the optimum flow rate of fermentation broth was 4.8 cm/h,the optimum pH was 8.5 and the optimum temperature was 30?.Under this separation condition,the dynamic adsorption capacity of resin 331 was 0.63 mg/mL.In addition,the optimum concentration of NaCl solution for daptomycin elution was 0.8 mol/L,and the elution rate was 93.3%.(5)The effect of six kinds of hollow fiber membranes on the removal of bacterial endotoxin from the purified daptomycin solution was investigated.It was found that the hollow fiber membrane of 15 KD had the best effect on the removal of bacterial endotoxin.The results demonstrated that 30 KD was suitable for the treatment of daptomycin fermentation broth,and then daptomycin could be effectively separated by the weak alkaline epoxy ion exchange resin 331.The combination of ion exchange resin and macroporous resin could obtain daptomycin with high purity.In addition,the hollow fiber membrane of 15 KD could be used to effectively remove the bacterial endotoxin from the purified daptomycin solution.