两步超滤膜法分离提取发酵液中聚苹果酸

Separation and purification of Poly(β-L-malic acid) in fermentation broth of Aureobasidium pullulansby a two-step ultrafiltration

采用两步超滤法对出芽短梗霉发酵产生的聚苹果酸进行分离与提取.发酵液经离心去除菌体后,先采用截留相对分子质量为30 000的超滤膜除去多糖及大分子杂质,接着采用截留相对分子质量为1 000的超滤膜对料液进行浓缩并除去小分子杂质,浓缩液经有机溶剂沉淀和冷冻干燥获得聚苹果酸.采取单因素实验法优化了超滤条件,结果表明:离心除菌后的发酵上清液稀释4倍,跨膜压差0.075 MPa,控制料液pH=6、温度35℃,使用相对分子质量30 000超滤膜稀释超滤1次,分子量1 000超滤膜浓缩4倍后,经甲醇沉淀和冷冻干燥,PMLA的纯度达到82.3%,PMLA的提取收率为57.56%.

In this study, a two-step ultrafiltration was applied to separate and concentrate PMLA from fermentation broth. Membranes with MWCO of 30 000 and 1 000 were feasible for separating PMLA from Pullulan and concentration, respectively. The best operational conditions of 30 000 membrane were as follows：transmembrane pressure 0. 075 MPa, dilution factor of 4, volume reduction ratio of 8, times of dilution diafiltration 1. The concentration factor of 1 000 membrane was 4. At the optimal conditions, the purity of PMLA increased to 82. 3%, and its recovery rate was 57.56%.