Identification of Lactobacillus helveticus LH59 genes involved in the biosynthesis of exopolysaccharides

摘要

Recombinant enzymes (I) for biosynthesis of exopolysaccharides (EPS) by a process that includes at least one step of forming a bond (in alpha or beta anomeric form) between C1, carrying the reducing aldehyde group of an activated D-Galp (galactose in pyranose form), and a phosphate group on a lipophilic or proteinaceous primer (II) are new. Independent claims are also included for the following: (1) nucleic acid (III) encoding (I); (2) recombinant vector containing (III); (3) cells containing (II), either integrated into the genome or present on a replicable plasmid, and able to express (I); (4) preparation of EPS by culturing cells transformed with vectors of (b); and (5) EPS produced this way (by assembling a single type of sugar unit) which contain a main chain with at least one branching lactose, bound to the main chain through its glucose component and with its galactose component linked to N-acetylgalactosamine, provided that it does not consist of repeats of the motif beta -D-GalpNAc(1-4) beta -D-Galp(1-4) beta -D-Glcp -5) beta -D-Galf((1-3) alpha -D-Galp)2 beta -D-Galp(1- GalpNAc = N-acetylgalacosamine; Glc = glucose; f indicates furanose form.