To validate such possible virulence impacts in the natural nisin sensitive mutant strains that are affected through the dlt operon deletion (TT82E with a 1172 bp deletion dlt operon deletion) as well as those with RsbU truncation (N11-1846) and VirBG120D (N12-2449) substitution were examined using a zebra fish embryo based infection model for virulence. This evidence concerns the gene CDAN1 and infection.