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Assessing the adhesion of probiotic bacteria on colonic epithelial cells (Bachelor thesis)

Κοντού, Στυλιανή/ Kontou, Styliani

Probiotics are live microbial supplements which when administered in adequate amounts confer a health benefit on the host by improving its intestinal microbial balance. They exhibit antimicrobial properties, modulate the host’s immune system and assist in multiple diseases’ treatments. The ability to adhere to the intestinal mucosa is one of the main selection criteria for probiotics. Adhesive strains are selected after in vitro experimentation using various adhesion models. Adhesion potency can be assayed by different methods such as plating, fluorescence microscopy and spectrofluorimetric detection. Various experimental parameters seem to affect the observations reported in the literature regarding adherence and colonization of probiotic bacteria onto in vitro/ex vivo models of the colonic epithelium. In this thesis, a flow cytometry-based cell adhesion assay is used to study a) the adhesion properties of Lactobacillus plantarum DSM 20174 and Lactobacillus rhamnosus GG, and b) the effect of time, concentration and trypsinization on their ability to adhere on the HT-29 colonic epithelium cell line of human origin. Our results indicate that both bacterial strains exhibited great adhesiveness to HT-29 epithelial cells, in a concentration and time -dependent manner. Moreover, the use of trypsin for HT-29 cell dissociation was observed to interfere with the adherence rate of the probiotics. Flow cytometry proved to be a great and quick alternative method in the probiotic adhesion assessment while specific parameters should be considered for the assay’s development. However, the comparison of the present method to the golden standard techniques used in the study of adhesion is recommended for the verification of its reliability.