Summary auto-generated
This study identified gamma-aminobutyric acid (GABA) production as a novel characteristic for distinguishing Lactococcus lactis subspecies. Researchers examined 37 lactic acid bacteria strains isolated from commercial cheese starters and 16 reference strains. They found that L. lactis subsp. lactis and L. lactis subsp. lactis biovar diacetylactis consistently produced GABA through glutamate decarboxylase (GAD) enzyme activity, while L. lactis subsp. cremoris strains produced no detectable GABA. GABA production correlated with arginine hydrolysis ability—a known distinguishing feature. The researchers measured GAD enzyme activity in culture samples and confirmed its presence in GABA-producing strains but absence in non-producing L. lactis subsp. cremoris. This discovery provides microbiologists with an additional biochemical test for rapid subspecies differentiation, complementing existing phenotypic methods based on growth temperature, salt tolerance, and fermentation patterns. The work suggests GABA production could be incorporated into diagnostic schemes for lactic acid bacteria used in dairy fermentation industries.
Key findings
- L. lactis subsp. lactis produces gamma-aminobutyric acid (GABA) while L. lactis subsp. cremoris does not
- GABA production correlates with glutamate decarboxylase (GAD) enzyme activity and arginine hydrolysis ability
- GABA production represents a novel and useful biochemical characteristic for distinguishing between L. lactis subspecies
- All tested strains of L. lactis subsp. lactis and biovar diacetylactis possessed GAD activity, while L. lactis subsp. cremoris strains completely lacked it
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Abstract
Lactococcus lactis strains were examined for their ability to produce γ-aminobutyric acid (GABA). Results showed that strains of L lactis subsp. lactis were able to produce this acid, whereas L. lactis subsp. cremoris were not. GABA production thus represents another effective characteristic for distinguishing L. lactis subsp. lactis from L. lactis subsp. cremoris.