Brown A K, Kaul A, Varley J
Biotechnology and Biochemical Engineering Group, Food Science and Technology Department, The University of Reading, Whiteknights, P.O. Box 226, Reading RG6 6AP, United Kingdom.
Biotechnol Bioeng. 1999 Feb 5;62(3):291-300. doi: 10.1002/(sici)1097-0290(19990205)62:3<291::aid-bit5>3.0.co;2-t.
Foam separation may have potential for protein recovery. However, for foam separation to be a viable protein recovery technique it is important to demonstrate, not only that high enrichments and recoveries can be achieved for single proteins, but also that high enrichments and recoveries, together with selectivity of partition, can be achieved for recovery from multi-component mixtures. Most process streams which require purification are indeed complex multi-component mixtures, for example, fermentation broths. In this study, three binary protein mixtures were chosen for continuous foam separation: beta-casein:lysozyme; Bovine serum albumin (BSA):lysozyme and beta-casein:BSA (mixtures 1, 2, and 3, respectively). For each of these mixtures, the expected outcome of each experiment, based on a previous knowledge and determination of relevant protein physical properties, was that the first protein should be preferentially separated into the foam phase. On the basis of results reported in Part I of this study for the continuous foam separation of beta-casein, conditions found to favor maximum enrichment were selected. For each mixture a range of concentrations of both proteins was considered. For mixture 1, maximum protein recoveries in the foam phase were 85.6% and 25% for beta-casein and lysozyme, respectively; and for mixture 2, maximum recoveries of 77. 6% and 18.9% were obtained for BSA and lysozyme, respectively. Maximum enrichment ratios in the foam phase were 79.4 and 2.5 for beta-casein and lysozyme respectively in mixture 1; and 74.0 and 1.4 for BSA and lysozyme respectively in mixture 2. Selective partitioning of beta-casein and BSA into the foam phase was obtained in mixtures 1 and 2, respectively, particularly for protein concentrations at which dilute protein films are known to form at the gas-liquid interface in the foam. Maximum partition ratios for mixtures 1 and 2 were 31.8 and 52.8, respectively. For mixture 3, both BSA and beta-casein were enriched into the foam phase. Maximum enrichments were 42.9 and 24.7 for BSA and beta-casein, respectively; however, selective partitioning in mixture 3 was limited (maximum partition ratio being 1.8).
泡沫分离在蛋白质回收方面可能具有潜力。然而，要使泡沫分离成为一种可行的蛋白质回收技术，不仅要证明对于单一蛋白质能够实现高富集率和高回收率，还要证明从多组分混合物中回收时能够实现高富集率、高回收率以及分配选择性。大多数需要纯化的工艺流实际上都是复杂的多组分混合物，例如发酵液。在本研究中，选择了三种二元蛋白质混合物进行连续泡沫分离：β-酪蛋白：溶菌酶；牛血清白蛋白（BSA）：溶菌酶和β-酪蛋白：BSA（分别为混合物1、2和3）。对于这些混合物中的每一种，基于先前的知识和相关蛋白质物理性质的测定，每个实验的预期结果是第一种蛋白质应优先分离到泡沫相中。根据本研究第一部分中关于β-酪蛋白连续泡沫分离的报道结果，选择了有利于最大富集的条件。对于每种混合物，考虑了两种蛋白质的一系列浓度。对于混合物1，β-酪蛋白和溶菌酶在泡沫相中的最大蛋白质回收率分别为85.6%和25%；对于混合物2，BSA和溶菌酶的最大回收率分别为77.6%和18.9%。混合物1中β-酪蛋白和溶菌酶在泡沫相中的最大富集比分别为79.4和2.5；混合物2中BSA和溶菌酶的最大富集比分别为74.0和1.4。在混合物1和2中，分别实现了β-酪蛋白和BSA向泡沫相的选择性分配，特别是对于已知在泡沫中气液界面形成稀蛋白质膜的蛋白质浓度。混合物1和2的最大分配比分别为31.8和52.8。对于混合物3，BSA和β-酪蛋白都富集到了泡沫相中。BSA和β-酪蛋白的最大富集分别为42.9和24.7；然而，混合物3中的选择性分配有限（最大分配比为1.8）。
