Exopolysaccharide biosynthesis in Lactococcus lactis NIZO B40: Functional analysis of the glycosyltransferase genes involved in synthesis of the polysaccharide backbone

We used homologous and heterologous expression of the glycosyltransferase g enes of the Lactococcus lactis NIZO B40 eps gene cluster to determine the a ctivity and substrate specificities of the encoded enzymes and established the order of assembly of the trisaccharide backbone of the exopolysaccharid e repeating unit. EpsD links glucose-1-phosphate from UDP-glucose to a lipi d carrier, EpsE and EpsF link glucose from UDP-glucose to lipid-linked gluc ose, and EpsG links galactose from UDP-galactose to lipid-linked cellobiose . Furthermore, EpsJ appeared to be involved in EPS biosynthesis as a galact osyl phosphotransferase or an enzyme which releases the backbone oligosacch aride from the lipid carrier.