Even when a protein is successfully expressed, perhaps even at a commercially viable titre, there can be undesired products from proteolytic cleavage fragments, post translational modifications, multimerization or improper folding. Phenotypeca’s toolbox contains solutions to all of these, and our breeding and QTL optimisation can improve on these further. We can remove/reduce the yeast encoded posttranslational modifications through engineering and breeding and can develop downstream processes that facilitate purification of the desired product away from modified proteins. If commercially and regulatory feasible, the protein sequence can be modified to exchange potentially modified residues to similar but unmodifiable residues. It may be desired to have specific modifications such as human glycosylation patterns. This is currently under development.