Mode of antimicrobial action of vanillin against Escherichia coli, Lactobacillus plantarum and Listeria innocua
Article first published online: 8 APR 2004
Journal of Applied Microbiology
Volume 97, Issue 1, pages 104–113, July 2004
How to Cite
Fitzgerald, D.J., Stratford, M., Gasson, M.J., Ueckert, J., Bos, A. and Narbad, A. (2004), Mode of antimicrobial action of vanillin against Escherichia coli, Lactobacillus plantarum and Listeria innocua. Journal of Applied Microbiology, 97: 104–113. doi: 10.1111/j.1365-2672.2004.02275.x
- Issue published online: 27 APR 2004
- Article first published online: 8 APR 2004
- 2003/1072: received 24 November 2003, revised 1 March 2004 and accepted 1 March 2004
- cytoplasmic membrane;
- Escherichia coli;
- Lactobacillus plantarum;
- Listeria innocua;
- mode of action;
- natural antimicrobial;
Aims: To investigate the mode of action of vanillin, the principle flavour component of vanilla, with regard to its antimicrobial activity against Escherichia coli, Lactobacillus plantarum and Listeria innocua.
Methods and Results: In laboratory media, MICs of 15, 75 and 35 mmol l−1 vanillin were established for E. coli, Lact. plantarum and L. innocua, respectively. The observed inhibition was found to be bacteriostatic. Exposure to 10–40 mmol l−1 vanillin inhibited respiration of E. coli and L. innocua. Addition of 50–70 mmol l−1 vanillin to bacterial cell suspensions of the three organisms led to an increase in the uptake of the nucleic acid stain propidium iodide; however a significant proportion of cells still remained unstained indicating their cytoplasmic membranes were largely intact. Exposure to 50 mmol l−1 vanillin completely dissipated potassium ion gradients in cultures of Lact. plantarum within 40 min, while partial potassium gradients remained in cultures of E. coli and L. innocua. Furthermore, the addition of 100 mmol l−1 vanillin to cultures of Lact. plantarum resulted in the loss of pH homeostasis. However, intracellular ATP pools were largely unaffected in E. coli and L. innocua cultures upon exposure to 50 mmol l−1 vanillin, while ATP production was stimulated in Lact. plantarum cultures. In contrast to the more potent activity of carvacrol, a well studied phenolic flavour compound, the extent of membrane damage caused by vanillin is less severe.
Conclusions: Vanillin is primarily a membrane-active compound, resulting in the dissipation of ion gradients and the inhibition of respiration, the extent to which is species-specific. These effects initially do not halt the production of ATP.
Significance and Impact of the Study: Understanding the mode of action of natural antimicrobials may facilitate their application as natural food preservatives, particularly for their potential use in preservation systems employing multiple hurdles.