Immunomodulatory effects of exopolysaccharides produced by Streptococcus thermophilus SBC8781 from soy or cow milk fermentation

NAKATA, HAJIME; SAHA, SUDEB; HIRAMITSU, MASANORI; INOUE, T; JULIO VILLENA; KITAZAWA, HARUKI

Hamburg

Congreso; 10th Congress of European Microbiologists - FEMS Congress 2023; 2023

FEMS

Exopolysaccharides (EPS) from lactobacilli gained attention not only because of their technological applications but in addition because their ability to modulate immune responses. However, the immunomodulatory capacities of EPS produced by Streptococcus thermophilus were less explored. In this work, EPS from S. thermophilus SBC8781 were isolated after soy or cow milk fermentation, identified, and characterized in terms of their abilities to modulate immunity in porcine intestinal epithelial (PIE) cells. Fresh soy or cow milks were inoculated with S. thermophilus SBC8781 (7 log CFU/ml) and incubated at 37oC for 24h. Extraction of EPS was performed by the ethanol precipitation method. EPS was characterized by chromatography and NMR. For immunomodulatory assays, PIE cells (3×104 cells/well) were stimulated with 100 µg/ml EPS from soymilk (EPS-s) or cowmilk (EPS-m) for 48h to evaluate their immunomodulartory activities after the stimulation with poly(I:C). EPS-s had higher number of acidic polysaccharides, however, its molecular weight was comparable to EPS-m. At atomic level, four NMR signals (2.5-2.8 ppm; acteyl group) were found for EPS-m, while multiple signals (3.5-4.3 ppm; α-anomeric) were detected in EPS-s. EPS-m and EPS-s yield produced by S. thermophilus SBC8781 was 200-240 mg/l and 50-70 mg/l, respectively. Studies in PIE cells showed that the EPS-s significantly reduce the expression of IL-6, IFN-β, A20 and Bcl-3 compared to EPS-m in response to TLR3 stimulation. Results indicate that EPS structure and immunomodulatory capacities produced by S. thermophilus SBC8781 vary according to the fermentation substrate. Soymilk fermented with the SBC8781 strain could be a new immunologically functional food.