酶法生产L-丝氨酸的分离纯化

Separation and purification of L-serine in enzymatic production

目的:用膜分离和离子交换技术分离纯化转化液中的L-丝氨酸。方法:以膜过滤去除菌体、蛋白质和色素,离子交换获得纯L-丝氨酸溶液,经反渗透膜浓缩制备L-丝氨酸。结果:用陶瓷膜去除菌体,氨基酸损失率为0.84%。除菌体后的转化液经超滤-纳滤输出的清液,加入碱或乙醇无蛋白质析出,透光率达90%以上,是活性炭脱色处理后滤液的2.5倍,氨基酸损失率为7%。L-丝氨酸与甘氨酸的离交分离条件为上柱流速55mL·min-1,解吸剂浓度0.08mol.L-1,解吸流速30mL·min-1。用反渗透膜浓缩解吸液,L-丝氨酸损失量仅为真空减压浓缩的40%。结论:用膜分离和离子交换技术分离纯化L-丝氨酸,优于传统的絮凝剂沉淀蛋白质、活性炭脱除色素和真空减压浓缩,可明显提高L-丝氨酸收率和产品质量。

Objective： To extract L-serine from the conversion solution using membrane separation and ion exchange. Methods： The bacteria and proteins as well as pigments in the conversion solution were removed through membrane filtration, the clear filtrate was further separated by ion exchange to obtain pure L-serine solution, and it was concentrated by reverse osmosis membrane： Results： For removing bacteria with ceramic membrane, the loss rate of amino acids in the conversion solution was 0.84%. Under certain conditions, no proteins were precipitated from the clear filtrate exported from UF and NF by adding alkali or ethanol, the transmittance of the clear filtrate at 460 nm was above 90% which was 2.5 times as much as that of activated carbon decolorization, and the loss rate of amino acids was 7%. The conditions of ion exchange separation for L-serine and glycine were determined to be sample loading flow rate of 55 mL.min- 1, desorbent of 0.08 tool＂ L-1 and desorption flow rate of 30 mL＂ min - When the desorption solution was concentrated by reverse osmosis membrane, the amino acids losses were 40% of that by vacuum. Conclusion： The efficiency of membrane separation and ion exchange to extract L-serine from the conversion solution is higher than traditional flocculation precipitation, activated carbon deeolorization and vacuum concentration. The separation recovery and product quality of L-serine are obviously improved by membrane separa- tion and ion exchange.