Scientists have demonstrated that the cholera bacteria, vibrio cholerae, can exist as a rather harmless form or, by phage conversion, can exist as a disease-causing, virulent form. this conversion is caused by

Transduction. This processes involves insertion of bacteriophage (viruses that infect bacteria) into the genome of a bacteria resulting to recombination. The bacteriophage DNA could contain virulent factors that convert an avirulent bacteria into a virulent type