This study was conducted to investigate the effects of bifidobacterial adherence to Caco-2 and MA-104 cell, and of crude peptidoglycan (cPGN) derived from bifidobacteria on
Escherichia coli O157: H7 and rotavirus infection
in vitro. The results obtained were as follows; at pH 6.6, distribution of cPGN particle size did not show any difference between physical and enzymatic treatment, while average particle size of physical and enzymatic treatment showed 1.26±0.17 and 1.35±0.21, respectively. And then, no differences in the distribution of particle size of bifidobacterial cPGN depending upon
Bifidobacterium strains tested were shown. Also, increasing effect of bifidobacterial adherence to Caco-2 cell was shown only to cPGN with enzymatic treatment. As bifidobacterial cPGN concentration increased, adherence ability of bifidobacteria to Caco-2 cell also increased. Nevertheless, no promoting effect was shown to bifidobacteria which possessed low adherence ability, and adherence of
E. coli O157: H7 to Caco-2 cell remained unchanged. Subsequently, it was shown that promoting effect of bifidobacterial cPGN on adherence of bifidobacteria to Caco-2 cell reduced adherence percentage of
E. coliO157: H7 relatively. In order to investigate the inhibitory effects of bifidobacteria-derived materials on rotavirus infection, effect of bifidobacterial cPGN was assessed by CPE observation and AEC staining method using MA-104 cell. Accordingly, dead cell mass (DCM) and cPGN had positive effectiveness on inhibition of rotavirus infection. Considering adherence ability of
Bifidobacterium infantis MAEIL-K9 to MA-104 cell and percentage of rotavirus infection, the higher adherence ability increased, the lower rotavirus infection decreased. Additionally, when
Bif. infantis MAEIL-K9 and cPGN were reacted with MA-104 cell simultaneously, adherence percentage of
Bif. infantis MAEIL-K9 increased with cPGN added, followed inhibitory effect of bifidobacteria on rotavirus infection also increased. Consequently, even though cPGN derived from bifidobacteria did not show inhibitory effect on
E. coliO157: H7, it was proven that adherence of
E. coli O157: H7 to Caco-2 cell was relatively inhibited by competition against adherence site, according to increment of adherence percentage of bifidobacteria. Moreover, bifidobacteria-derived cPGN and adherence percentage of bifidobacteria appeared to be protective against human and bovine rotavirus infection. In conclusion, relying upon increment of bifidobacterial viable cell counts, its adherence ability, and adherence-promoting materials to Caco-2 cell, inhibitory effects of bifidobacteria on
E. coli O157: H7 and rotavirus infection seemed to be much higher.
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