S. thermophilus is one of the most important bacteria in the food industry and used to produce yogurt, cooked cheeses, and soft cheeses. S. thermophilus has been shown to survive in a 0.4% oxgall concentration (highest bile concentration of duodenum) and a pH of 2 for 3 hours, demonstrates a high adherence to the intestinal mucosa, and is highly antibiotic resistant (Khali, 2009). S. thermophilus is a viable bacterium that enhances the composition of colonic microbiota (Liu et al., 2010), and therefore has the ability to exert probiotic effects such as inflammatory reductions, inhibition of carcinogen production, enhanced immunity, and as a possible treatment in chemo-therapy induced intestinal mucositis.
By reducing cytokines that play significant roles in inflammatory disease, S. thermophilus has been suggested a possible therapy in intestinal and systemic disease. S. thermophilus has been shown to suppress IL-17 expression and production by splenocytes (Oquita et al., 2011). S. thermophilus has been used to treat chronic gastritis by reducing IFN-ƴ and TNF-α, and increasing the thickness of the gastric mucus gel layer (Rodriguez et al., 2010).
S. thermophilus enhances the immune system via diverse set of mechanisms. First, S. thermophilus is able to transfer genes (CRISPR3/Cas) directly to pathogenic bacteria, such as E. coli (Sapranauskas et al., 2011). CRISPR3/Cas cleaves bacteriophage DNA, and thus provides protection against viral gene transfer and bacterial infection (Barrangou et al., 2007). Second, S. thermophilus secretes antimicrobial bacteriocins that directly prevent the adhesion and colonization of pathogenic bacteria (Gilbreth & Somkuti, 2005). Finally, in a mouse model, S. thermophilus stimulated T-cells when presented with pathogens (Shimosato et al, 2009). Because S. thermophilus is able to positively influence the colonic microbiota, S. thermophilus may be an important supplement following the use of antibiotics, during times of increased mental stress, and prior to/following travel to polluted cities.