Role of the β-glucan surface polysaccharide in Propionibacterium freudenreichii: physiological and immunomodulatory properties

Abstract

P. freudenreichii (PF) is a Gram + species, with the GRAS (Generally Recognized As Safe) status in the USA and a Qualified Presumption of Safety (QPS) status in Europe. It is widely consumed by humans because it is an essential ripening culture in Swiss type cheeses (Emmental, Leerdammer®…), and also as a probiotic in food supplement (Propio-Fidus®). Recently, PF was shown to produce a (1→3, 1→2)-β-D-glucan polysaccharide. A single gene (named gtf) is responsible for the biosynthesis of this surface polysaccharide, that has been immunodetected for 30% of the 100 strains of PF tested. Here we investigated the role(s) of this β-D-glucan