Hello;

I use a random peptide phage library to isolate specific peptides to PDL-1. I use the commercial host strain ER2738 for phage amplification and titration and the selection system is based on counting blue plaques on IPTG/X-Gal plates. Unfortunately my host has been contaminated by phages similar to my own phages since I get too many blue plaques when I plate the bacteria without phages!!!

I changed the bacterial stock, I bleached and autoclaved everything, but still I get contamination!

Does anyone have any experience with that?