PhD thesis of Anne Brillet-Viel (2002-2005)

In order to develop a strategy for biopreservation of smoked salmon against Listeria monocytogenes, the inhibitory capacity of 3 strains of Carnobacterium isolated from fish and producing bacteriocin was tested. C. Divergens V41 maintains the level of Listeria at less than 50 CFU / g in sterile smoked salmon for 28 days at 4 and 8 ° C thanks to the action of divercin V41. For its use in the product, the culture of the strain was optimized on a medium without animal protein. On commercial smoked salmon, the strain slightly inhibits the endogenous flora and does not alter the sensory quality, but it produces a biogenic amine, tyramine. A negative tyramine mutant was obtained by chemical mutagenesis. Its characterization showed that it does not have enzymatic activity due to the presence of a stable mutation in the structural gene for tyrosine decarboxylase (1863 bp). The C. Divergens V41A8 mutant has the characteristics of a good biopreservation agent.