Probiotics and Antimicrobial Proteins

, Volume 6, Issue 2, pp 82–87 | Cite as

In Vitro Antibacterial Mechanism of Action of Crude Garlic (Allium sativum) Clove Extract on Selected Probiotic Bifidobacterium Species as Revealed by SEM, TEM, and SDS-PAGE Analysis

  • J. Booyens
  • M. C. Labuschagne
  • M. S. ThantshaEmail author


There has been much research on the effects of garlic (Allium sativum) on numerous pathogens, but very few, if any, studies on its effect on beneficial, probiotic bifidobacteria. We have recently shown that garlic exhibits antibacterial activity against bifidobacteria. The mechanism by which garlic kills bifidobacteria is yet to be elucidated. This study sought to determine the mechanism of action of garlic clove extract on selected Bifidobacterium species using scanning and transmission electron microscopy and SDS-PAGE analysis. SEM micrographs revealed unusual morphological changes such as cell elongation, cocci-shaped cells with cross-walls, and distorted cells with bulbous ends. With TEM, observed changes included among others, condensation of cytoplasmic material, disintegration of membranes, and loss of structural integrity. SDS-PAGE analysis did not reveal any differences in whole-cell protein profiles of untreated and garlic clove extract-treated cells. The current study is the first to reveal the mechanism of action of garlic clove extract on probiotic Bifidobacterium species. The results indicate that garlic affects these beneficial bacteria in a manner similar to that exhibited in pathogens. These results therefore further highlight that caution should be taken especially when using raw garlic and probiotic bifidobacteria simultaneously as viability of these bacteria could be reduced by allicin released upon crushing of garlic cloves, thereby limiting the health benefits that the consumer anticipate to gain from probiotics.


Garlic Allium sativum Bifidobacterium Scanning electron microscopy Transmission electron microscopy Probiotic 



The authors are grateful to the National Research Foundation (NRF) and the University of Pretoria for funding, the Unit for Microscopy and Microanalysis of the University of Pretoria, particularly Mr. Alan Hall and Mr. Chris van der Merwe for technical assistance, and Dr. Michael Crampton of the Molecular Biology Division, BioSciences, CSIR, Pretoria, for assistance with SDS-PAGE analysis.

Conflict of interest

All authors have no conflict of interest to declare.


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Copyright information

© Springer Science+Business Media New York 2013

Authors and Affiliations

  • J. Booyens
    • 1
  • M. C. Labuschagne
    • 1
  • M. S. Thantsha
    • 1
    Email author
  1. 1.Department of Microbiology and Plant Pathology, Faculty of Natural and Agricultural SciencesUniversity of PretoriaPretoriaSouth Africa

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