Changes in gene expression and metabolites release in Listeria monocytogenes in response to high pressure homogenization and heat treatments

摘要

Minimal food processing is widely used in order to improve food safety and reduce side effects associated with strong treatments such as heat treatments. High Pressure Homogenization (HPH) is one of the most promising non-thermal technologies for fluid foods whose potential has been widely explored for both food decontamination and product diversification. However, stress response mechanisms and the increased microbial resistance to sub-lethal factors after adaptation to processing stresses, which may counteract the effectiveness of such a preservation technology and compromise food safety, have not been fully investigated yet. The aim of this work, performed within the European project HighQ RTE, was to investigate how the exposure to two industrially important processes, i.e. HPH and heat treatments, can affect the gene expression and the metabolic activity of a strain of Listeria rnonocytogenes (56Ly). In particular the expression of 7 genes related to general or heat stress response, i.e. rpoB, gadA, opuCA, groES, groEL, clpC, clpP, was monitored by Real Time RT-PCR over a 24 hour period of exposure to different levels of thermal (15, 30, 60, 120 sec at 70℃) and HPH (20, 40, 60, 80 and 100 MPa) treatments.