title: Activity of p-aminobenzoic acid compared with other organic acids against selected bacteria.
abstract: The antibacterial activity of p-aminobenzoic acid against Listeria monocytogenes, Salmonella enteritidis and Escherichia coli was compared with the activity of commonly used acidulants: formic, propionic, acetic, lactic and citric acids. Viable count evaluations and MIC determinations indicated that p-aminobenzoic acid caused greater inhibitory effects than the other organic acids. The activity of p-aminobenzoic acid on the growth of the test organisms at selected pH values indicated that p-aminobenzoic acid was more active at low pH than at high pH. Uptake studies showed that the uptake of p-aminobenzoic acid by E. coli was markedly decreased as the pH values increased. Electron micrographs of E. coli cells grown in the presence of p-aminobenzoic acid indicate that p-aminobenzoic acid caused marked damage to the cell envelope. It is suggested that p-aminobenzoic acid has at least two mechanisms of action: one mechanism in common with other organic acids and the other mechanism by interfering with the synthesis of the peptidoglycan layer by an action on the dihydrofolate reductase enzyme.
authors.affiliation: School of Pharmacy, Robert Gordon University, Aberdeen, UK.
authors.forename: R M
authors.initials: RM
authors.lastname: Richards
authors.forename: D K
authors.initials: DK
authors.lastname: Xing
authors.forename: T P
authors.initials: TP
authors.lastname: King
mesh_terms: D010129:4-Aminobenzoic Acid / Q000494:pharmacology*; D002264:Carboxylic Acids / Q000494:pharmacology*; D004926:Escherichia coli / Q000187:drug effects* / Q000648:ultrastructure; D006863:Hydrogen-Ion Concentration; D008089:Listeria monocytogenes / Q000187:drug effects*; D008826:Microbial Sensitivity Tests; D012477:Salmonella enteritidis / Q000187:drug effects*
chemical_list: D002264:Carboxylic Acids; D010129:4-Aminobenzoic Acid