Caister Academic Press

Antimicrobial activity of the genus Bifidobacterium

Ismail Fliss, Arthur C. Ouwehand, Ehab Kheadr, Sampo Lahtinen, and Stephen J. Davids
from: Bifidobacteria: Genomics and Molecular Aspects (Edited by: Baltasar Mayo and Douwe van Sinderen). Caister Academic Press, U.K. (2010)


In view of their relative abundance in the large intestine, their totally inoffensive nature and their reputation as symbionts, bifidobacteria are viewed by many scientists as probable antagonists of many would-be colonizers of the large intestine. While science cannot at this point confirm that the beneficial effects of probiotics such as bifidobacteria necessarily include specific antimicrobial mechanisms that eliminate pathogens or prevent other intestinal bacteria from reaching numbers that lead to health problems, quite a few high-quality studies show how bifidobacteria might have such effects. Among the most likely antagonistic mechanisms, prodigious production of lactic and acetic acids, which in addition to lowering the ambient pH may act as metabolic inhibitors, should be considered the most significant. Another plausible mechanism is competition for adhesion sites on the intestinal epithelium. There is evidence that bifidobacteria secrete molecules of large molecular mass with the specific function of interfering with the attachment of other organisms. Other mechanisms, such as hydrogen peroxide or bacteriocin production are more speculative. The effectiveness of bifidobacteria as antagonists of pathogens or as competitors for epithelial adhesion sites varies considerably and appears to be strain-dependent read more ...
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