Abstract: The invention relates to a method for generating a Streptococcus thermophilus strain exhibiting a “high galactose utilization” profile, which is characterized by a high percentage of consumed galactose at the maximum speed of lactose consumption and optionally a high percentage of consumed galactose at the end of lactose consumption (both as determined by assay I), comprising modifying the sequence of the gal-lac gene cluster. The invention also relates to a Streptococcus thermophilus strain obtained or obtainable by this method, to a Streptococcus thermophilus strain characterized both by the sequence of its gal-lac gene cluster and its “high galactose utilization” profile, to a culture and kit-of part comprising such strains, as well as to the use of such strains in food applications.

Abstract: The invention relates to a polynucleotide comprising a lacZ gene (lacZFS) encoding a ?-galactosidase characterized by a particular profile regarding its efficiency of hydrolysis of lactose. The invention is also directed to a Streptococcus thermophilus strain comprising a lacZFS allele and bacterial composition thereof, and their use to obtain fermented milk not undergoing post-acidification.

Abstract: The invention relates to a lactose-positive, galactose-negative, Streptococcus thermophilus strain carrying a mutation in 2 or 3 genes selected from the group consisting of 1) a gene encoding a protein of the mannose-glucose-specific PTS and a glcK gene, 2) a gene encoding a protein of the mannose-glucose-specific PTS and a ccpA gene, and 3) a gene encoding a protein of the mannose-glucose-specific PTS, a glcK gene and a ccpA gene, wherein said strain, when used to ferment milk, provides a low lactose fermented milk and/or a fermented milk not undergoing acidification when stored at fermentation temperature.