Environmental stress affects S-Layer production by Lactobacillus acidophilus IBB801 and Lactobacillus helveticus CRL 1177

BROWN, L.; GROSU-TUDOR, S.S.; HEBERT, E.M.; MOZZI, F.; ZAMFIR, M.

Simposio; 11th International Symposium on Lactic Acid Bacteria. HEALTH, SUSTAINABILITY, DIVERSITY, AND APPLICATION; 2014

Several lactic acid bacteria have the potential to promote the health of the host or to prevent and treat diseases. Such bacteria are referred to as probiotic which must resist multiple stresses, including the gastrointestinal (GI) conditions and food processing. Once cells have survived the GI tract, they can colonize and grow to adequate numbers to exert their beneficial effect to the host. Several factors protect the bacterial cell from harsh environmental conditions such as the presence of S-layer. S-layer proteins are non-covalently bound to the cell wall and assemble into surface layers with high degrees of positional order often completely covering the cell wall. In this study we aimed to gain insight on S-layer production by the health-promoting strains Lactobacillus acidophilus IBB801 and L. helveticus CRL 1177 subjected to the following culture (stress) conditions: i) presence of bile salts (0.05, 0.1, and 0.2%); ii) incubation temperature (42 or 45°C); and iii) osmotic stress (0.6, 2.0 and 3.0% NaCl). S-layer from lactobacilli was extracted by using LiCl and analyzed by SDS-PAGE and transmission electron microscopy. Under stress conditions, S-protein bands from L. acidophilus IBB801 became visible in the gels being stronger in presence of 2% NaCl (osmotic stress) and 0.2% bile salts. In contrast, L. helveticus CRL 1177 showed increased production of S-layer in presence of 0.6% NaCl and against heat stress (45° C). S-layer production by L. acidophilus IBB801 and L. helveticus CRL 1177 was increased under specific stress conditions and helped the strains to maintain cell viability under the assayed detrimental environment. Further studies are needed to prove the S-layer protective role in these bacteria.