A novel approach in acidic disinfection through inhibition of acid resistance mechanisms; Maleic acid-mediated inhibition of glutamate decarboxylase activity enhances acid sensitivity of Listeria monocytogenes

• Published in: Food microbiology 2018-02, Vol.69, p.96-104
• Main Authors: Paudyal, Ranju, Barnes, Ruth H., Karatzas, Kimon Andreas G.
• Format: Article
• Language: English
• Subjects: Bacterial Proteins - antagonists & inhibitors; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Biofilm; Biofilms; Disinfectants - pharmacology; Disinfection - instrumentation; Disinfection - methods; Enzyme Inhibitors - chemistry; Enzyme Inhibitors - pharmacology; GAD; Gene Expression Regulation, Bacterial; Glutamate decarboxylase; Glutamate Decarboxylase - antagonists & inhibitors; Glutamate Decarboxylase - genetics; Glutamate Decarboxylase - metabolism; Hydrogen-Ion Concentration; Inhibition; Kinetics; Listeria monocytogenes; Listeria monocytogenes - drug effects; Listeria monocytogenes - enzymology; Listeria monocytogenes - genetics; Listeria monocytogenes - physiology; Maleates - chemistry; Maleates - pharmacology; Maleic acid
• ISSN: 0740-0020; 1095-9998
• DOI: 10.1016/j.fm.2017.07.013

Here it is demonstrated a novel approach in disinfection regimes where specific molecular acid resistance systems are inhibited aiming to eliminate microorganisms under acidic conditions. Despite the importance of the Glutamate Decarboxylase (GAD) system for survival of Listeria monocytogenes and other pathogens under acidic conditions, its potential inhibition by specific compounds that could lead to its elimination from foods or food preparation premises has not been studied. The effects of maleic acid on the acid resistance of L. monocytogenes were investigated and found that it has a higher antimicrobial activity under acidic conditions than other organic acids, while this could not be explained by its pKa or Ka values. The effects were found to be more pronounced on strains with higher GAD activity. Maleic acid affected the extracellular GABA levels while it did not affect the intracellular ones. Maleic acid had a major impact mainly on GadD2 activity as also shown in cell lysates. Furthermore, it was demonstrated that maleic acid is able to partly remove biofilms of L. monocytogenes. Maleic acid is able to inhibit the GAD of L. monocytogenes significantly enhancing its sensitivity to acidic conditions and together with its ability to remove biofilms, make a good candidate for disinfection regimes. •Maleic acid is an inhibitor of the GAD system of L. monocytogenes.•Maleic acid could be used to enhance the antimicrobial effects of acid-based disinfection regimes.•Maleic acid due to its high antibacterial activity it can reduce numbers of microorganisms without further pH reduction.•Maleic acid can successfully remove biofilms of L. monocytogenes.