Growth of Carnobacterium divergens V41 and production of biogenic amines and divercin V41 in sterile cold-smoked salmon extract at varying temperatures, NaCl levels, and glucose concentrations

A complete factorial design 2(3) was used to study some aspects of Carnobacterium divergens V41 metabolism (growth, biogenic amine production, and divercin V41 production) in sterile cold-smoked salmon extract (SSE) at varying temperatures (3 to 9degreesC), NaCl levels (2.5 to 6.5% ) and glucose concentrations (2 to 6 g liter(-1)). The results showed that temperature and NaCl content were the most influential factors on growth parameters in SSE. Predictive models are suggested for the assessment of C. divergens lag time (t(lag)) and maximum specific growth rate (mu(max)). Among the biogenic amines studied only tyramine was found to be produced by C divergens in SSE. Furthermore, we showed that temperature, NaCl, and glucose variations did not greatly affect tyramine and divercin V41 production by the bacteria under the experimental conditions used. Indeed, divercin V41, a bacteriocin from C. divergens V41 that is highly active against some Listeria strains, was produced in SSE even under harsh culture conditions. Similarly, tyramine production in SSE was delayed at 3degreesC but reached 35 mug ml(-1) in all experiments after 27 days of storage. However, this final tyramine, concentration in SSE is low compared with the threshold values of 100 to 800 mug g(-1) reported as the potentially toxic dose in foods. Thus, we have found that C. divergens V41 is a promising strain for the biopreservation of refrigerated cold-smoked salmon.