Schematic representation of the EPS biosynthetic pathway in L. lactis leading to the synthesis of B40-EPS. Glycolysis is depicted on the left and leads to the production of pyruvate, which is then converted into lactate by lactate dehydrogenase (LDH). The glycolytic intermediate glucose-6-phosphate (glucose-6P) is converted to glucose-1-phosphate (glucose-1P) by the action of phosphoglucomutase (PGM). Glucose-1-phosphate is the central intermediate in the conversions leading to the B40-EPS precursors UDP-glucose, UDP-galactose and dTDP-rhamnose. The final step of EPS biosynthesis involves a multienzyme pathway encoded by the eps genes (EPS machinery). GalU, UDP-glucose pyrophosphorylase; GalE, UDPgalactose epimerase; Rfb, glucose-1-phosphate thymidylyltransferase, TDP-glucose oxidoreductase, dTDP-4-dehydrorhamnose 3,5-epimerase, dTDP-4-keto-L-rhamnose reductase.