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Appl. Environ. Microbiol., 02 1997, 506-512, Vol 63, No. 2
S Fujiwara, H Hashiba, T Hirota and JF Forstner
We have examined the competitive binding of several species of
Bifidobacterium and Escherichia coli Pb176, an enterotoxigenic E. coli
(ETEC) strain, to gangliotetraosylceramide (asialo GM1 or GA1), a common
bacterium-binding structure, and identified a factor(s) in the
Bifidobacterium culture supernatant fluid that inhibits the binding of E.
coli Pb176 to GA1. The ETEC strain we used expresses colonization factor
antigen (CFA) II, which consists of coli surface-associated antigens CS1
and CS3. Competitive exclusion of ETEC from GA1 molecules by
Bifidobacterium cells was found by an in vitro thin-layer chromatography
overlay binding suppression assay. However, the ETEC cells were less
effective in blocking the adherence of Bifidobacterium cells to GA1. These
findings suggest that the two bacterial species recognize different binding
sites on the GA1 molecule and that the mechanism of competitive exclusion
is not due to specific blockage of a common binding site on the molecule.
The neutralized culture supernatant fluids of Bifidobacterium species,
including that of Bifidobacterium longum SBT 2928 (BL2928), showed
remarkable inhibition of the ETEC binding to GA1. Our results suggest that
the binding inhibitor produced by BL2928 is a proteinaceous molecule(s)
with a molecular weight around or over 100,000 and a neutral isoelectric
point. The binding inhibitor produced by BL2928 and other Bifidobacterium
species is estimated to contribute to their normal anti- infectious
activities by preventing the binding of pathogenic strains of E. coli to
GA1 on the surface of the human intestinal mucosa.
Copyright © 1997, American Society for Microbiology
Proteinaceous factor(s) in culture supernatant fluids of bifidobacteria which prevents the binding of enterotoxigenic Escherichia coli to gangliotetraosylceramide
Technology and Research Institute, Snow Brand Milk Products Co., Ltd., Kawagoe, Japan.
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