Hi Mary, I have a suggestion, we never used magnetic Ni beads but we tried to isolate M13 -phage with the His-tagged protein expressed on gene III on a Ni-NTA column, we were never successful in it. we carried out few optimizations like changing the elution buffer concentration and loaded high titer of phage but no success. we think the phage can non-specificaly interact with the Ni-beads and hard to wash them off.

Thanks for your input!

Hi Mary, 

I have tried this. I would be cautious as the sequenced phages from my panning all contained, you guessed it, multiple histidine residues. This was the case even when I included negative selections.    

Just adding my comment, though coming late, but it may help future phage display 'screeners'. I used both streptavidin, neutravidin and Ni beads. I got more specfic binders with biotinylated proteins (avi-tagged) while, like Jeffery rightly said, His-tagged proteins generated a lot of non-specific binders with so much histidine residues. My suggestion is: avoid Ni beads for phage display screens.