Abstract
The concentrations of γ-aminobutyric acid (GABA) in 22 Italian cheese varieties that differ in several technological traits markedly varied from 0.26 to 391 mg kg
−1
. Presumptive lactic acid bacteria were isolated from each cheese variety (total of 440 isolates) and screened for the capacity to synthesize GABA. Only 61 isolates showed this activity and were identified by partial sequencing of the 16S rRNA gene. Twelve species were found.
Lactobacillus paracasei
PF6,
Lactobacillus delbrueckii
subsp.
bulgaricus
PR1,
Lactococcus lactis
PU1,
Lactobacillus plantarum
C48, and
Lactobacillus brevis
PM17 were the best GABA-producing strains during fermentation of reconstituted skimmed milk. Except for
L. plantarum
C48, all these strains were isolated from cheeses with the highest concentrations of GABA. A core fragment of glutamate decarboxylase (GAD) DNA was isolated from
L. paracasei
PF6,
L. delbrueckii
subsp.
bulgaricus
PR1,
L. lactis
PU1, and
L. plantarum
C48 by using primers based on two highly conserved regions of GAD. A PCR product of ca. 540 bp was found for all the strains. The amino acid sequences deduced from nucleotide sequence analysis showed 98, 99, 90, and 85% identity to GadB of
L. plantarum
WCFS1 for
L. paracasei
PF6,
L. delbrueckii
subsp.
bulgaricus
PR1,
L. lactis
PU1, and
L. plantarum
C48, respectively. Except for
L. lactis
PU1, the three lactobacillus strains survived and synthesized GABA under simulated gastrointestinal conditions. The findings of this study provide a potential basis for exploiting selected cheese-related lactobacilli to develop health-promoting dairy products enriched in GABA.