Identification of a gene cluster for the biosynthesis of a long, galactose-rich exopolysaccharide in Lactobacillus rhamnosus GG and functional analysis of the priming glycosyltransferase

A gene cluster is identified that has encoded the enzymes and regulatory and transporter proteins for the different steps in the biosynthesis of extracellular polysaccharides (EPS) of the probiotic strain Lactobacillus rhamnosus GG. The characterization of the welE mutant has shown that deprivation of the long, galactose-rich EPS molecules has resulted in an increased adherence and biofilm formation capacity of Lactobacillus rhamnosus GG, because of less shielding of adhesins such as fimbria-like structures.