Recovery of proteins from corn and soybean extracts by membrane adsorption.

Efficient separation strategies for the recovery of high-value proteins (native or recombinant) from plant agriculture are an important aspect of many different processes, from biopharmaceuticals to byproduct recovery during biofuel production. Here we report the use of membrane adsorption for the recovery of proteins from soybean and corn extracts, and compare the results with packed bed adsorption. Two alternative operating modes were investigated, a flowthrough strategy and a bind and elute method. Overall, membrane adsorption provided faster throughput, and had equal or slightly higher dynamic binding capacities compared with resin beads, without compromising yield and purity of the chosen target. Soybean was found to be an ideal plant host when capturing native protein on an anion exchange medium. This provided an opportunity to capture a large percentage (>80%) of native protein as the product, and/or allowed for elevated enrichment factors (>20) during purification of a recombinant target with pI > 7.0, using a flowthrough approach. On the other hand, for corn, a single ion-exchange step was not able to capture more than 60% of the native protein. However, the bind and elute method with corn as the host for a recombinant product allowed for higher enrichment factors compared to soybean. In all cases, the concentration of a recombinant protein (as dictated by expression level) was found to play a significant role in the level of dynamic binding capacity, with higher concentration leading to elevated capacity. Likewise, a higher concentration of competing proteins was shown to decrease the overall capacity of a recombinant target.