New lactic acid bacteria

A polynucleotide encoding a β-galactosidaseFS, which consist of an amino acid sequence identified by SEQ ID NO:4;

• and which is defined as a lacZ allele which increases the ratio of the activity of lactose importation of the LacS permease at pH 4.5 over the activity of lactose hydrolysis of the beta-galactosidase at pH 4.5 above 8 in a DGCC715 derivative, said DGCC715 derivative being a strain DGCC715 (deposited at the DSMZ on Feb. 12, 2019 under the accession number DSM33036), into which its lacZ gene was replaced by said polynucleotide encoding a β-galactosidaseFS.