Acid tolerance of Listeria monocytogenes

Abstract:

Listeria monocytogenes, an important zoonotic foodborne pathogen, encounters acidic environments such as silage, fermented food, stomach and phagolysosomes. It contains a number of enzyme systems to deal with acid stress: F0F1-ATPase, glutamate decarboxylase, arginine deiminase and agmatine deiminase. The bacterium could maintain its intracellular pH (pHi) homeostasis when exposed to environmental pH (pHex) 4.5, survives well in pHex 3.5. Preexposure of L. monocytogenes cells to mild acid stress (pHex 4.5) could induce acid tolerance response (ATR) that could render them more resistant to fatal acidic stress. SigB (σB) is a positive regulator of ATR, enabling the bacterium to better cope with environmental stresses. Therefore, σB could be a target for development of novel antibacterial drugs. Stringent control of L. monocytogenes contamination in fermented food is of great importance to minimize the risk of listeria infections to consumers.