The eps locus of Streptococcus thermophilus IP6756 is not involved in exopolysaccharide production

The sequence analysis of the eps locus of Streptococcus thermophilus IP6756 shows that it is very different from all other eps loci studied in S. thermophilus: it is smaller and displays only a few open reading frames (ORFs) compared with other eps loci. Moreover, none of the identified ORF encodes glycosyltransferases, which are required for exopolysaccharides (EPS) production, whereas IP6756 is an EPS-producing strain. The functional study of this locus shows that it is organized in an operon and that its polar interruption does not lead to any modification in EPS yield. These results indicate that the eps locus of S. thermophilus IP6756 is not involved in EPS production and describe for the first time that EPS production is under the control of gene(s) encoded elsewhere in the genome in S. thermophilus.