The particular behaviour of Listeria monocytogenes under sub-optimal conditions

Listeria monocytogenes is a ubiquitous pathogenic microorganism which has been described as growing at temperatures of interest to food production and especially at low temperatures (− 2 ° to 8 δC) in storage processes. However, the general relationship between the maximum specific growth rate, μ max and temperature has not often been studied for L. monocytogenes in the whole temperature range from minimal to maximal growth temperature. A global analysis of this relationship for temperatures between − 2 ° and 42 °C was therefore done. The global shape of this relationship was that usually observed for microorganisms, especially in the neighbourhood of the optimal temperature, T opt. But a more detailed study showed the existence of a so-called “change temperature”, occurring between 10 ° and 15 °C, below which L. monocytogenes grows faster than one would expect. This implies that the minimal growth temperature of both studied strains of L. monocytogenes is lower than expected.