膜错流过滤对透明质酸发酵液的分级研究

Fractionalization of hayluronic acid fermentation broth by cross-flow microfiltration and ultrafiltration

膜错流过滤可实现混合液中物质的分级,在生物工程领域有着广泛的应用,其过滤特性与水力条件及溶液性质有密切关系.分别采用0.45μm、0.20μm微滤膜和截留分子量3000、100000超滤膜,对其错流过滤透明质酸发酵液的特性参数进行了研究.超滤膜在稳态时的通量大于微滤膜稳态时的通量,微滤膜、超滤膜的最佳操作压力分别为0.1 MPa,0.15 MPa,最佳流速应为1.25 m/s,透明质酸浓度以2 g/L以下为宜.在pH=4,增加的离子强度为0.2-0.25 mol/L NaCl时,微滤膜对透明质酸有85%的透过率,且通量增大,而菌体被完全截留;超滤膜在pH=7,增加的离子强度为0.2-0.25 mol/L NaCl时,蛋白质对透明质酸有很高的筛分系数,透明质酸被选择性截留.研究表明,微滤和超滤相结合可实现发酵液中透明质酸分离.

Cross-flow filtration （microfiltration and ultrafiltration）, is widely used in biological engineering as the fraction of mixture. The fractionalization of the hyaluronic acid （HA） fermentation broth by cross- flow filtration was studied with microfiltration membranes （0.45 μm, 0.20μm in pore diameter） and ultrafiltration membranes （MWCO 300 k, 100 k）. It was shown that the flux of ultrafiltration in the stable （or quasi - stable） state was larger than that of microfiltration. The optimal tangential velocity was 1.25 m/s, preferable HA concentration was below 2 g/L, and the most favorable applied pressure was 0.1 MPa for microfiltration and 0.15 MPa for ultrafiltration respectively. When operated in the condition of pH 4.0 and enhanced ionic strength with 0.2-0.25 mol/L NaCl, the permeation of HA for microfiltration membranes was about 85 % with higher flux and total rejection of bacterial bodies. For ultrafiltration membranes, HA would be selectively rejected while proteins got higher relative permeation in pH 7.0 and enhanced ionic strength with 0.2-0.25 mol/L NaCl. As a consequence, the combination of microfiltration and ultrafiltration can achieve the separation of HA from the fermentation broth.