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

Abstract

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 crosswalls 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 affect 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.1

Fourier transform infra-red spectroscopy and flow cytometric assessment of the antibacterial mechanism of action of aqueous extract of garlic (Allium sativum) against selected probiotic Bifidobacterium strains

“…Electron micrographs showed that garlic induced unusual morphological changes in bifidobacteria [5]. It is however not yet known whether garlic inhibition on probiotic cells is confined to the cell membrane or if there are other targets.…”

Allium sativum

“…Studies indicated that garlic could affect benefi cial probiotic Bifi dobacterium species in a manner similar to that exhibited in pathogens (Booyens et al 2014 ). The results highlight that caution should be taken especially when using raw garlic and probiotic bifi dobacteria simultaneously as the viability of these bacteria could be reduced by allicin released upon the crushing of garlic cloves, thereby limiting the health benefi ts that the consumer anticipates to gain from probiotics.…”

In Vitro Evaluation of Antibacterial Activity of Garlic Allium Sativum Against Poultry Pathogens and Effect of Garlic Supplementation on Duckling Growth Performance

“…Several mechanisms have been proposed for the antibiotic activity of garlic, including modulation of sulfhydryl enzymes, inhibition of RNA synthesis, and partial inhibition of DNA and protein synthesis [10]. Recently, Booyens et al (2014) investigated the antibacterial mechanism of crude garlic clove extract by using electron microscopy. The micrographs obtained showed the change of morphology such as cell elongation, distorted cells with bulbous ends and the condensation of cytoplasmic material, disintegration of membranes, loss of structural integrity of garlic clove extract-treated cells and leading to the cell death [11].…”

“…Recently, Booyens et al (2014) investigated the antibacterial mechanism of crude garlic clove extract by using electron microscopy. The micrographs obtained showed the change of morphology such as cell elongation, distorted cells with bulbous ends and the condensation of cytoplasmic material, disintegration of membranes, loss of structural integrity of garlic clove extract-treated cells and leading to the cell death [11].…”

“…The antibacterial activity of garlic is widely attributed to allicin. Previous studies demonstrated that allicin blocked the action of bacterial enzymes by reacting with thiols, inhibited RNA synthesis and thereby inhibited the growth of the micro-organism [11,12]. However, this constituent is photo-and thermo-sensitive, and easily metabolized into various compounds.…”