In Vitro And In Vivo Studies On Survival Of Some Probiotic Bacteria In Gastrointestinal Tract

The potential probiotic characteristics of L. acidophilus ATCC 4356, L. johnsonii ATCC33200 and B. bifidum ATCC2203 were studied, with regard to acid / bile salt tolerance and survival in simulated gastric and intestinal juices. Furthermore, an in vivo feeding experimental was adopted to estimate the transit tolerance of potentially probiotics in the gastrointestinal tract of Japanese quail chicks and their antagonistic effect against some harmful organism (E .coli).
Results of in vitro experiments revealed that L. johnsonii was the most acid tolerant, and possessed the highest figures for viable cell counts, actually 7.61 and 7.88 log cfu / ml after 180 min. of incubation at pH 2.0 and 3.0respectiely. Also, it could be noticed that B.bifidum ATCC 2203 survived better than L. acidophilus ATCC 4356, either at pH 2.0 or 3.0.
             Moreover, L.acidophilus ATCC 4356 was selected as the highest bile tolerance at 0.3 % (w/v) bile concentration, while at 0.5 and 1.0 (w/v) bile, L. johnsonii ATCC33200 was more resistance. In contrast, B. bifidum ATCC2203 was the most sensitive strain at different tested bile salt concentrations, and exhibited great reduction in its viable counts after 180 min. of incubation, being 1.95, 2.07 and 2.81 Log cfu / ml at 0.3, 0.5 and 1 % (w/v) bile concentrations, respectively.
Furthermore, L. johnsonii ATCC33200 was the most tolerance strain to either gastric or intestinal juices, followed by B. bifidum ATCC2203, the gave survival % of 100 % and 98%.45%, respectively  after 60 min of exposure  to gastric juice, while the corresponding figures were 102.19 % and 100 % after 360 min. of exposure to intestinal juice. Contrarily, L .acidophilus ATCC 4356 ranked slight decreases of 0.32 and 013 log cycles after 60 and 360 min. of exposure to gastric and intestinal juices, respectively.
The results of in vivo feeding experiment declared that the count of L .acidophilus ATCC 4356 recovered from the small intestine of Japanese quail chicks decreased by 1.23 log cycle after 2h of feeding, while B. bifidum ATCC2203 showed less decrease being 1.09 log cycle. However, both tested strain were successfully transit through gastrointestinal tract with viable cell count attained 107cfu/g.
In order to investigate the antagonistic effect of both potential probiotic strains against E. coli, three trails were conducted. Results obtained revealed that birds receiving basal diet for 5 days, led to increase in the count of E.coli by 3.87 log cycles and attained 7.75 log cfu/g in feces samples. While, feeding on traditional yoghurt, reduce the count of E.coli to 5.90 log cfu/g. Moreover, the highest reduction in E.coli counts, being 5.03 log cycles was detected in samples of birds administered acidophilus – bifidus – yoghurt for 5 days. This statement may be ascribed to antagonistic behavior of B. bifidum and L. acidophlus.