Inhibition of bacterial spore growth by fatty acids and their sodium salts

Abstract

The antimicrobial activity of 11 fatty acids and their salts was tested on spores of Clostridium botulinum 62A, Clostridium sporogenes PA3679, and Bacillus cereus F4165/75. Linolenic acid was the most inhibitory fatty acid and lauric acid was the most inhibitory of the saturated fatty acids. Minimum inhibitory concentrations ranged from 50- 150 μg/ml for lauric acid, ≥ 150 μg/ml for myristic acid, 30-100 μ/ml for linoleic acid, and 10-75 μg/ml for linolenic acid depending on the strain. Caprylic, capric, palmitic, stearic, arachidic, and erucic acids showed only partial inhibition (44 to 90%) at concentrations as high as 150 μg/ml. Addition of 0.2-0.3% (wt/vol) starch neutralized the inhibitory effect of palmitic, linoleic, and linolenic acids but had no effect on lauric acid even when increased to 1%. Lauric, linoleic, and linolenic acids were shown to inhibit spore germination as measured by loss of spore heat resistance.