Abstract
The purpose of this work was to assess in vitro the probiotic characteristics of
Enterococcus faecium CRL183 and Lactobacillus helveticus ssp jugurti 416, having
as an aim to verify some characteristics which are essential to the microorganisms,
in order to be considered as probiotic. Firstly, the capacity of these microorganisms
to resist to pH 1.5, 2.0, 3.0 and 4.0 was tested in a specific culture medium for
each species. Then the survival test to the gastrointestinal passage was done, and
the conditions of the stomach and small intestine were simulated, so determining
the viability of these bacteria comparing with pepsin at pH 2.0 and pancreatin at pH
8.0. The resistance to bile salts was assessed by inoculating Enterococcus
faecium CRL183 and Lactobacillus helveticus ssp jugurti 416 in a culture medium
supplemented with 0,1; 0,2; 0,3 and 0,5 % of Oxgall. However, for the production
test of the hydrolase of bile salts, it was verified the occurrence of change in color
of the colonies, or the precipitation of the bile salts taurodeoxycholic and
glycodeoxycholic (TDCA and GDCA). In the auto-aggregation and co-aggregation
studies, these strains were placed separately (auto-aggregation) and associated
(co-aggregation), and then the optical density was verified (DO560), for completion
and adhesion intestinal epithelium was tested Enterococcus faecium CRL183 and
Lactobacillus helveticus ssp jugurti 416 with the Escherishia coli 0157: H7. The
production of antagonist substances by both studied microorganisms was tested in
comparison with Escherishia coli 0157: H7, Listeria monocytogenes V2 and
Salmonella enteriotidis, by using the spot-on-the-lawn test. The results
demonstrated that the microorganisms resisted to all pH. These bacteria also
showed to be tolerant to the survival test to the gastrointestinal passage and also
to the survival test to bile salts, though in this test, Enterococcus faecium CRL183
obtained a shorter delay time in relation to Lactobacillus helveticus ssp jugurti 416.
Nevertheless, the results obtained for the test of hydrolase of bile salts
demonstrated that Enterococcus faecium CRL183 was able to reduce both studied
bile salts, while Lactobacillus helveticus ssp. jugurti 416 hydrolyzed TDCA,
showing to be sensitive to GDCA. The percentage of auto-aggregation was
approximately 80% for each microorganism and the co-aggregation between them
was 25,4%. The E.faecium CRL183 and L. helveticus ssp jugurti 416 was
adherent cells and reduce 60% adherence the E. coli 0157: H7.Neither E.faecium
CRL183, nor L. helveticus ssp jugurti 416 showed production of bactericidal
substances, including bacteriocins, in the presence of E. coli 0157: H7, L.
monocytogenes V2 and S. Enteritidis.The according with this results the
Enterococcus faecium CRL 183 and the Lactobacillus helveticus ssp. jugurti 416
present characteristics for considerate probiotics.
keywords: microorganisms probiótics, Enterococcus faecium CRL 183,
Lactobacillus helveticus ssp. jugurti 416