Introduction of the exopolysaccharide gene cluster from Streptococcus thermophilus Sfi6 into Lactococcus lactis MG1363: production and characterization of an altered polysaccharide

Abstract

Summary Streptococcus thermophilus

Potentials of Exopolysaccharides from Lactic Acid Bacteria

“…sakei 0-1 has yielded a strain that produces an EPS with different monosaccharide composition [62]. Heterologous expression of EPS gene clusters is the tool for biosynthesis of EPS and oligosaccharides of interest [63]. EPS of novel structural features can be manufactured by shuffling the gene coding for glycosyltransferase.…”

The complete cps gene cluster from Streptococcus thermophilus NCFB 2393 involved in the biosynthesis of a new exopolysaccharide

“…An AT rich region, 5h-AAA-ACGTTTTTTTGTTTTTTTTTGAAAAAAA-3h, similar to the consensus sequence of an upstream promoter (UP) element, 5h-NNAAA(AT)(AT)T(AT)T-TTTNNAAAANNN-3h (Estrem et al, 1998) was identified upstream of the k35 box of the cpsA gene between positions k72 and k42. UP elements have been reported to stimulate promoter activity up to 30-fold, and are found both in Gram-negative and Gram-positive bacteria (Estrem et al, 1998 , 1997 ;Sau et al, 1997 ;Stingele et al, 1999). No hairpin loops resembling putative rho-independent transcription terminators were found within the cps genes ; however one was identified downstream of orf14.9.…”

Biofilm Exopolysaccharides of Pathogenic Fungi: Lessons from Bacteria

“…The ability of a single glycosyl transferase to display specificities for multiple donor and recipient sugars has also been reported in studies of the S. thermophilus EPS system (24). As described above, transfer of the eps operon to a GalNAc-deficient bacteria results in the substitution of galactose for GalNAc within the mature polymer (24), suggesting that either Gal or GalNAc can serve as a suitable substrate during polymer synthesis. This promiscuity of transferase activity suggests that the acetyl group of GalNAc is not part of the recognition signal for the binding of nucleotide sugars by these enzymes.…”

“…In these bacteria, UDP-GalNAc is derived from other cellular metabolic pathways that are not specific to exopolysaccharide synthesis. This difference is best illustrated by experiments in which the entire S. thermophilus eps operon was expressed in Lactococcus lactis, which lacks endogenous GalNAc production (24). Although the operon was functional in L. lactis, the resulting polymer was altered in composition and was deficient in GalNAc, suggesting that this sugar is derived from other cellular processes and is not produced by enzymes encoded within the exopolysaccharide biosynthetic operon (24).…”