Recovery of lysozyme from hen egg white by selective magnetic cake filtration

A new concept for the improvement of the downstream processing and purification is the so-called magnetic separation. By using surface functionalized magnetic substrate particles, which selectively adsorb the target product, it can be directly separated out of a crude bioprocess stream. These methods are already used for analytical purposes, where only small amounts of functionalized particles are necessary. To apply the same concept at a larger scale, effective and economical procedures have to be provided. First, suitable process equipment has to be developed. Second, the magnetic particles have to be manufactured with a stable surface functionalization and long-term stability for their reuse. Up to now mainly high-gradient magnetic separation filter devices are applied for selective magnetic separation. They consist of a magnetic matrix in which the magnetic particles are trapped. In this work, a new magnetic filter is introduced that overcomes the capacity limitations of the current high-gradient magnetic separation technology. The principle is demonstrated by selective recovery of lysozyme from hen egg white. Prior to the separation experiments magnetic beads with a strong acid cation-exchange surface functionalization are synthesized. The separation procedure is implemented in only one unit operation. With the implementation of the displacement elution sequence lysozyme can be separated out of a hen egg white solution with a purification factor of PF = 36 and a purity P = 0.83.