Triton X 100 is used to increase the solubility of the protein when used in the lysis buffer for bacterial lysis. But I am not sure how much percentage can be used so that it increases the solubility of my his-tagged protein and doesn't effect the binding of the protein into the Ni-NTA beads. If, someone is using Triton x-100 in their lysis buffer, I would like to know how much final percentage is safe for Ni-NTA protein purification.