PCR amplification and digestion with AseI of the gadB gene in isolates from cheese starters. Conditions for PCR and electrophoresis are described in Materials and Methods. Lanes: 1, L. lactis subsp. lactis biovar diacetylactis NIAI 01-7; 2, L. lactis subsp. lactis ATCC 19435; 3, L. lactis subsp. cremoris ATCC 19257; 4, L. lactis subsp. cremoris 53-2; 5, L. lactis subsp. cremoris 53-6.