Variability of the response of 66Listeria monocytogenesandListeria innocuastrains to different growth conditions

Impact of microbial variability on food safety and quality

“…When the standard deviations are similar for all growth conditions such as in our study, the CV ratio will increase when the growth conditions become unfavourable. We also observed larger variability in  max near the growth boundary for pH than for NaCl conditions, which corresponded to the previous result from Lianou and Koutsoumanis (2011a) Begot et al (1997) showed that strains originating from industrial environments were among the faster growing strains. It was suggested that those strains were accustomed to growing in a wide range of harsh conditions allowing them to adapt to unfavourable conditions.…”

“…The strain variability in lag phase duration, however, was reported higher than the variability in  max (Begot et al, 1997). Although lag phase duration is important for the prediction, yet it is laborious and difficult to obtain.…”

“…Variability in microbial growth kinetics have been observed in studies using Staphylococcus aureus , Salmonella (Lianou and Koutsoumanis, 2011a;Oscar, 2000) and Listeria (Barbosa et al, 1994;Begot et al, 1997) species. The variability of  max among Salmonella enterica strains was reported to be greater than within strain variability (Lianou and Koutsoumanis, 2011a).…”

“…However, these parameters, such as the maximum specific growth rate ( max ) (Barbosa et al, 1994;Begot et al, 1997;, lag phase (Aguirre et al, 2013), growth limit Van der Veen et al, 2008), D-value (De Jesús andWhiting, 2003;Linton et al, 1990;Lou and Yousef, 1996), and z-values , vary depending on several factors amongst others within and between strain, cells history, physiological state of the cells and food matrices. Therefore, the prediction results might vary from one study to the others due to differences in the parameters used to generate the prediction.…”

nfluences of physicochemical stresses on injury and inactivation behaviour of Listeria innocua

“…Besides the criticism of some researchers in assuming the parallelism of both species in a variety of foods and processing conditions, there are a considerable number of works that validate L. innocua as a primary non-pathogenic indicator of L. monocytogenes (Zhang, Ma, Oyarzabal, & Doyle, 2007;Lecompte, Kondjoyan, Sarter, Portanguen, & Collignan, 2008). The similarity of growth properties of both species in a wide range of temperatures, pH and water activity values re-enforces the choice of working with a non-pathogenic species (Begot, Lebert, & Lebert, 1997). The majority of L. innocua strains are more heat resistant than L. monocytogenes, thus providing a margin of safety in the development/design of new thermal processes involving these microorganisms (Friedly et al, 2008).…”