Applied Microbiology and Biotechnology, 100 (8), pp. 3667-3679.
Kebouchi, M., Galia, W., Genay, M., Soligot-Hognon, C., Lecomte, X., Awussi, A. A., Perrin, C., Roux, É., Dary, A., Le Roux, Y.
2016
Streptococcus thermophilus (ST) is a lactic acid
bacterium widely used in dairy industry and displays several
properties which could be beneficial for host. The objective of
this study was to investigate, in vitro, the implication of
sortase A (SrtA) and sortase-dependent proteins (SDPs) in
the adhesion of ST LMD-9 strain to intestinal epithelial cells
(IECs) and resistance to bile salt mixture (BSM;
taurocholoate, deoxycholate, and cholate). The effect of mutations
in prtS (protease), mucBP (MUCin-Binding Protein),
and srtA genes in ST LMD-9 in these mechanisms were examined.
The HT29-MTX, HT29-CL.16E, and Caco-2 TC7
cell lines were used. HT29-MTX and HT29-CL.16E cells
express different mucins found in the gastro intestinal tract;
whereas, Caco-2 TC7 express cell surface proteins found in
the small intestine. All mutants showed different adhesion
profiles depending on cell lines. The mutation in genes srtA
and mucBP leads to a significant decrease in LMD-9 adhesion
capacity to Caco-2 TC7 cells. A mutation in mucBP gene has
also shown a significant decrease inLMD-9 adhesion capacity
to HT29-CL.16E cells. However, no difference was observed
using HT29-MTX cells. Furthermore, ST LMD-9 and srtA
mutant were resistant to BSM up to 3 mM. Contrariwise, no
viable bacteria were detected for prtS and mucBP mutants at
this concentration. Two conclusions could be drawn. First,
SDPs could be involved in the LMD-9 adhesion depending
on the cell lines indicating the importance of eukaryotic-cell
surface components in adherence. Second, SDPs could contribute
to resistance to bile salts probably by maintaining the
cell membrane integrity.