Isolation and characterization of a Listeria monocytogenes mutant strain hyperproducing virulence factors.

A mutant strain characterized by hyperproduction of a number of cell wall and supernatant proteins was isolated after N'methyl-N'-nitro-N-nitrosoguanidine treatment of Listeria monocytogenes strain NCTC10527. Several of these proteins were identified as virulence factors. When a wild-type strain was grown in the presence of activated charcoal it was shown to exhibit the same protein pattern as the isolated mutant.