engleski

S-layer as functional surface protein of probiotic strain Lactobacillus brevis D6

The autochthonous strain D6, which was identified as Lactobacillus brevis, carries a 45-kDa S-layer protein. This strain displayed the highest percentage of autoaggregation (70.37% ± 5.79 in 5h) among lactic acid bacteria (LAB) strains tested, and the autoaggregation was affected by the removal of S-layer proteins by 5M guanidine hydrochloride (GHCl) (54.87±7.13 in 5h). Since S-layer proteins have been identified within lactic acid bacteria (LAB), only among representatives of Lactobacillus species, it was of special interest to study its functional role in Lb. brevis D6. Subsequently, the capacities of the Lb. brevis D6 to adhere to extracellular matrix proteins (ECM) and intestinal epithelial cell lines in vitro were assayed. The removal of the S-layer proteins reduced the adhesive ability of the strain D6 to Caco-2 cell lines and ECM components, while its adhesiveness to the IPEC-1 cell line was low. Pathogen exclusion through coaggregation ability and survival in simulated conditions of the gastrointestinal tract (GIT) and during freeze drying of Lb. brevis D6, before and after GHCl extraction of S-layer proteins from the cell surface, were followed. Results implied on potential S-layer protective functions on Lb. brevis D6 cells under aforementioned stress conditions. Additionally, cytokine production in monocyte-derived dendritic cells (moDC) and moDC maturation in response to Lb. brevis D6 bacterial cells and its purified S-layer proteins were determined by ELISA and FACS, respectively. However, no immunodulatory effects were observed, besides a slight induction of TNF-alpha, IL-12 and IP-10 production. The results suggest that the S-layer protein enhances certain probiotic activities of Lb. brevis D6, particularly protection in rigorous GIT conditions and adhesion to intestinal cell lines.

S-layer; Lactobacillus; Adhesion; Immunomodulation

nije evidentirano