Study On Separation And Purification Of L-tryptophan In Fermentation Broth

L-tryptophan is mainly produced by fermentation, L-tryptophan fermentation liquid of composition is extremely complex, including L-tryptophan, other amino acids, residual sugars, proteins, inorganic salts, and so on.In order to obtain pure L-tryptophan, a series of physical and chemical separation processes must be applied. In this study, L-tryptophan fermentation liquid was used as the main materials.The content of fermentation liquid components,building analytic methods of amino acids,decoloring and the separation of amino acids in L-tryptophan fermentation liquid were studied systematacially in order to gain the new and more effectively reactive ways, which could supply the technical foundation for the industry in some degree.1%In order to confirm separation objects,the componens of L-tryptophan fermentation liquid were detailedly analysed.The results show they include65.53%water and34.47%solid matter(1.26%L-tryptophan0.14%glutamic、3.76%inorganic salts、0.10%residual sugars and29.05%proteins etc).Establish rapid determination method for1-tryptophan、glutamic acid in fermented broth.A method to determine1-tryptophan in fermented broth was developed by high performance liquid chromatogyaphy (HPLC).An Agilent C18(4.6x250mm,5um) was used with the mobile phase0.03%KH2PO4water solution and methanol (the ratio of volume was90to10).The flow rate was at1.0ml/min, Column temperature39℃and the detective wavelength was278nm.The method was rapid,accurate and simple with a good linearity (R2=0.9999) in the range of0-1.0g/L for L-tryptophan. A method to determine glutamic acid in fermented broth was developed by SBA-40D Biosensor Analyzer, Features of the method are:analysis of simple operation, fast, low cost, high accuracy and so on.2、The decoloring conditions of L-tryptophan fermentation liquid are studied by active carbon and D301R resin.The best decoloring conditions of active carbon include emperature25℃、0.5g per100mL fermented broth、pH2-4and decoloring20min, in the condition, the decoloring rate is92.6%,and the loss of L-tryptophan is6.9%. Then D301R resin:emperature25℃、 the flow rate was at1.0mL/min、pH5-6、Light transmittance of the fermented broth is 30%, in the condition, the decoloring rate is94.8%,and the loss of L-tryptophan is8.6%.3、Separation and purification of L-tryptophan from the fermented broth.The optimal separation and purification conditions for L-tryptophan extraction from the fermentation broth were as following:using D061cation exchange resin to adsorb,2.0mol/L NH3to elute, D301R resin to decolorate, and finally the extranted L-tryptophan was concentrated and crystallized.The total recovery rate is71.8%, and purity is98.4%.