Purification Of Kelimycin By Multiply Solvent Extraction And Quality Controlling Of Fermentation Broth

Kelimycin,composed of acylated spiramycins,is a kind of macrolide antibiotics.Many complex impurities similar to effective components in properties and structure would appear during fermentation process.There is a strict requirement for components contents in product.The downstream of purification process is the key point to the production of kelimycin.Solvent extraction,including washing,back-extraction,and crystallization steps,is the main method to purify kelimycin in industrial production.Though with mature technology,this process shows little selectivity for effective components and impurities,which made it difficult to obtain high qualified product.In order to separate impurities more effectively and improve the qualification rate of the products,conditions of the solvent extraction process were optimized.Furthermore,second solvent extraction process,adding two steps of extraction and back-extraction on the basis of the original process,was developed in this paper.The corresponding technological parameters of the second solvent extraction process were studied.At the same time,impurities among effective components can be divided into strong,middle,and weak polar impurities according to different polarities,which made it convenient to adopt corresponding measures to separate impurities.This research also summarized the relationship of the components distributions in fermentation broth and the obtained product.The method of controlling components contents in fermentation broth was proposed,providing the material basis for the production of qualified kelimycin.Research shows that:?1?In solvent back-extraction process,0.7%NaH₂PO₄ was regarded as the optimal extraction phosphate concentration;Compared with oxalic acid,phosphoric acid was more suitable as the acidity regulator;The stable pH value for kelimycin in back-extraction solution was 4.0-6.0.?2?In crystallization process,components distribution,especially percentage of impurities,was taken as the promise of optimizing crystallization process.The most suitable terminal pH value was 7.5-8.0,temperature was 25-35?.?3?In second solvent extraction process,it is conductive to optimize components distributions in kelimycin product,when extraction aqueous:organic ratio was 5:1,and back-extraction organic:aqueous ratio was 1:6.?4?When percentage of impurities among effective components was more than 4%,it was impossible to improve the qualification rate in further refinery for the unqualified kelimycin.?5?The quality of kelimycin fermentation broth shows great influence on components distributions in kelimycin product.Components percentage was controlled in broth and the indicators are as follows:?Iso?Valeryspiramycin III>10%,?Iso?Valeryspiramycin ?+?+?>17%,acylated spiramycin>40%,impurities between acetylspiramycin ? and acetylspiramycin ? ?3.7%,impurities between propionylspiramycin? and propionylspiramycin ? ?3.0%.The second solvent extraction process,proposed in this paper,could improve the qualification rate effectively.Components distributions were proposed as the controlling basis for the refined and fermentation process,showing important guiding significance for the controlling of product quality.