Direct capture of lactoferrin from whey using magnetic micro-ion exchangers in combination with high-gradient magnetic separation

An automated process for bioproduct recovery using magnetic micro-ion exchangers (MMIX) and the technique of high-gradient magnetic separation (HGMS) was developed with the recovery of lactoferrin from crude whey being chosen as a model system. The first step of the design of the separation process was the optimisation of binding and elution conditions for the target protein on the millilitre scale. Second, the magnetic filter used for particle separation was characterised by breakthrough studies. On the basis of the results of these pre-studies, a separation process for the recovery of lactoferrin was designed, which consisted of: (i) binding of the target protein to MMIX particles in a batch reactor, (ii) recovery of the loaded MMIX particles from whey using high-gradient magnetic separation, (iii) washing of the MMIX particles to remove loosely bound solids, (iv) elution of the target protein. Finally, the complete process was automated and conducted over three full cycles. To allow for multi-cycle processing, it was necessary to include a recovery step (v) in which the MMIX particles were equilibrated and pumped back into the batch reactor, where they were mixed with a new batch of whey to start another process cycle. A model for the estimation of the theoretical productivity (space-time yield) of the process was developed as a tool for comparison with other recovery processes. Furthermore, the influence of the MMIX particle concentration and particle size applied shall be discussed.