Maleic Acid is a Glutamate Decarboxylase (GAD) inhibitor of E. coli and L. monocytogenes. IC50 & Target: GAD^[1][2]. In Vitro: The MICs of WT 10403S for the acids (e.g., Maleic Acid) are 34 mM, 25 mM, 31 mM and 30 mM which correspond to pH values prior to growth of 4.84, 5.14, 5.32 and 5.02 respectively. Of all compounds tested, Maleic Acid is the least inhibitory despite acting at a lower pH (4.84). The most acid resistant (10403S) and the weakest (EGD-e) strain are challenged with 8.6 mM and 4.3 mM of each organic acid at pH 3 and 3.3 respectively. On both strains, Maleic Acid is the most bactericidal^[2].