Relationships between the inhibitory efficacy and physicochemical properties of six organic acids and monolaurin against Bacillus weihenstephanensis KBAB4 growth in liquid medium

Organic acids are widely used in foodstuffs to inhibit pathogen and spoiler growth. In this study, six organic acids (acetic, lactic, propionic, phenyllactic, caprylic, and lauric acid) and monolaurin were selected based on their physicochemical properties: their molecular structure (carbon chain le...

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Published in:Food microbiology 2024-08, Vol.121, p.104498-104498, Article 104498
Main Authors: Dutoit, Agathe, Decourcelle, Nicolas, Mathot, Anne-Gabrielle, Coroller, Louis
Format: Article
Language:English
Subjects:
Acids
Bacillus
Bacillus cereus group
Carbon
Chemical structure
Growth inhibition
Laurates
Lauric Acids - pharmacology
Lipophilicity
MIC
Monoglycerides - chemistry
Monoglycerides - pharmacology
pKa
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Summary:Organic acids are widely used in foodstuffs to inhibit pathogen and spoiler growth. In this study, six organic acids (acetic, lactic, propionic, phenyllactic, caprylic, and lauric acid) and monolaurin were selected based on their physicochemical properties: their molecular structure (carbon chain length), their lipophilicity (logP), and their ability to dissociate in a liquid environment (pKa). The relation between these physicochemical properties and the inhibitory efficacy against B. weihenstephanensis KBAB4 growth was evaluated. After assessing the active form of these compounds against the strain (undissociated, dissociated or both forms), their MIC values were estimated in nutrient broth at pH 6.0 and 5.5 using two models (Lambert & Pearson, 2000; Luong, 1985). The use of two models highlighted the mode of action of an antibacterial compound in its environment, thanks to the additional estimation of the curve shape α or the Non-Inhibitory Concentration (NIC). The undissociated form of the tested acids is responsible for growth inhibition, except for lauric acid and monolaurin. Moreover, long-carbon chain acids have lower estimated MICs, compared to short-chain acids. Thus, the inhibitory efficacy of organic acids is strongly related to their carbon chain length and lipophilicity. Lipophilicity is the main mechanism of action of a membrane-active compound, it can be favored by long chain structure or high pKa in an acid environment like food. •PKa and chemical structure influenced the inhibitory efficacy of a compound.•Predictive models highlighted the mode of action of acid inhibition.•Growth inhibition is not always dictated by the undissociated form of acid.•Low MIC values are linked to greater lipophilicity of the compound.
ISSN:0740-0020
1095-9998
DOI:10.1016/j.fm.2024.104498