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 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.
