Background: Probiotic strains are live micro-organisms that, when consumed in adequate amounts, confer a health benefit on the host. Probiotic bacteria selected for commercial use in foods and in therapeutics must retain the characteristics for which they were originally selected. The adhesion to intestinal cells is considered a fundamental property of a probiotic strain. Adhesion to intestinal cells has been related to shortening the duration of diarrhea, immunogenic effects, competitive exclusion, and other health effects. Therefore, adhesion properties should be carefully monitored. Moreover adhesion characteristic of different probiotic strains may be an important quality-control method for assessing gut barrier effects. The aim of this study was to analyze the characteristics of adhesiveness of three strains of Bifidobacterium spp. selected as probiotic bacteria for commercial use in Italy. Methods: The adhesion of Bifidobacterium subsp. lactis BB-12, Bifidobacterium longum W11 and of an untyped Bifidobacterium bifidum on human colon cancer HT-29 cells was carried out according to the method described by Ali et al. (World Acad Sc Eng Techn, 49, 2009). Particularly, the count of the adherent cells was performed by calculating the average number of cells in ten different immersion microscopy fields using the method described by Guglielmetti et al. (Appl. Envir Microbiol., 76, 2010). In addition, the ability to form biofilm by bacteria adherent to the HT- 29 cells was verified by scanning electron microscope (Jeol JSM 25S). Results: After 30’ incubation, we observed that the number of B. bifidum bacteria adherent to the HT-29 cells was significantly higher, than that detectable in the other two strains. However, after 60’ incubation, an more evident increase of adherent cells especially for B. animalis subsp. lactis and, to a lesser extent, for B. bifidum and B. longum was observed. The observation by scanning electron microscope has confirmed these features. In addition, the SEM observation showed the production of biofilm-like structures features mainly by B. longum strain. Conclusions: Our study has confirmed that the probiotic strains of Bifidobacterium spp. tested had different characteristics of adhesiveness. Further studies are needed to characterize the structures involved in the mechanisms of the adhesion.
|Titolo:||Study on the adhesion characterstics of Bifidobacterium spp.strains on human epithelial cell line HT-29.|
|Data di pubblicazione:||2013|
|Appare nelle tipologie:||4.1 Contributo in Atti di convegno|