4. Conclusions
The increasing interest to promote health in a natural way has intensified research in the field of probiotics. The importance of the biological characteristics of phenolic compounds, specifically at the daily dose recommended for olives and their synergisms with probiotics, motivated our studies.
The Caco-2 cell viability observed points to no toxicity effect of both OL and HT at the tested levels. On the contrary, these compounds can inhibit proliferation of human colon adenocarcinoma cells, thus supporting the claim that their intake can reduce risk of cancer.
Our study provided new insight into the biological effects of (physiological) levels of phenolic compounds upon biofilm formation by a probiotic strain upon control of pathogen adhesion. It became clear that biofilm production on abiotic conditions is not necessarily associated with adhesivity on biotic surfaces. Data on biofilm formation and composition (by probiotics and E. coli) suggest that bacterial colonization of biotic or abiotic surfaces results from distinct physiological processes, as bacterial adhesion and biofilm formation. Under our assay conditions, biofilm composition and adhesion capacity appear not necessarily associated to each other.
The strongly increasing in adhesion degree of L. plantarum 33 after biofilm establishment prompting us to go in further depth toward evaluation of the correlation between biofilm formation and adhesion capacities. Our findings on the role of biofilm formation and on further adhesion are promising, and should thus be explored in complementary studies on the underlying mechanisms.