目的 用超滤-纳滤膜分离法去除L-色氨酸酶法转化液中的蛋白质和色素.方法 L-色氨酸转化液经适当处理后,输入超滤膜和纳滤膜设备,分别收集输出的清液和浓液,然后检测其透光率并用加入碱或乙醇方式,检查转化液中蛋白质、色素的去除效果.结果 在转化液pH调节至5.5 ～6.0、温度控制在20～25℃的膜分离工艺条件下,经超滤-纳滤输出的清液,加入碱或乙醇无蛋白质析出,透光率达85％以上,比使用活性炭脱色处理的滤液高2.7倍.结论 膜分离法去除转化液中蛋白质和色素的效果明显优于传统的絮凝剂沉淀蛋白质和活性炭脱除色素,从而为酶法生产L-色氨酸提供了一条绿色、先进的纯化工艺.%Purpose The ultrafiltration(UF) combined with nanofiltration ( NF) membrane separation was used to remove proteins and pigments from enzymatic conversion solution of L-tryptophan. Methods The conversion solution of L-tryptophan with certain treatments was inputed into UF and NF membrane filtration equipments, and then clear filtrate and cloudy filtrate through these equipments were collected respectively. The efficiency of removing proteins and pigments from the conversion solution with membrane separation was examined by determining the transmittance of the filtrate and adding alkali or ethanol into the filtrate. Results The conversion solution was adjusted to pH 5. 5-6. 0,and feeding temperature was 20-25 t. Under these operating conditions,no proteins were precipitated from the clear filtrate by adding alkali or ethanol. The transmittance of the clear filtrate at 460 nm was above 85% which was of 2. 7 times as high as that of activated carbon decolorization. Conclusion The efficiency of membrane separation for removing proteins and pigments from the conversion solution was obviously better than traditional flocculation precipitation and activated carbon decolorization used in the experiment. It developed a green and advanced purification process for enzymatic production of I-tryptophan.
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