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Phenotypic, Technological, Safety, and Genomic Profiles of Gaba-Producing Lactococcus lactis and Streptococcus thermophilus Strains Isolated from Cow’s Milk
Valenzuela, J.A.; Vázquez, L.; Rodríguez, J.; Flórez, A.B.; Vasek, O.M.; Mayo, B. Phenotypic, Technological, Safety, and Genomic Profiles of Gamma-Aminobutyric Acid-Producing Lactococcus lactis and Streptococcus thermophilus Strains Isolated from Cow’s Milk. Int. J. Mol. Sci.2024, 25, 2328.
Valenzuela, J.A.; Vázquez, L.; Rodríguez, J.; Flórez, A.B.; Vasek, O.M.; Mayo, B. Phenotypic, Technological, Safety, and Genomic Profiles of Gamma-Aminobutyric Acid-Producing Lactococcus lactis and Streptococcus thermophilus Strains Isolated from Cow’s Milk. Int. J. Mol. Sci. 2024, 25, 2328.
Valenzuela, J.A.; Vázquez, L.; Rodríguez, J.; Flórez, A.B.; Vasek, O.M.; Mayo, B. Phenotypic, Technological, Safety, and Genomic Profiles of Gamma-Aminobutyric Acid-Producing Lactococcus lactis and Streptococcus thermophilus Strains Isolated from Cow’s Milk. Int. J. Mol. Sci.2024, 25, 2328.
Valenzuela, J.A.; Vázquez, L.; Rodríguez, J.; Flórez, A.B.; Vasek, O.M.; Mayo, B. Phenotypic, Technological, Safety, and Genomic Profiles of Gamma-Aminobutyric Acid-Producing Lactococcus lactis and Streptococcus thermophilus Strains Isolated from Cow’s Milk. Int. J. Mol. Sci. 2024, 25, 2328.
Abstract
Gamma-aminobutyric acid (GABA) is thought to have beneficial effects on human health and well-being. GABA enrichment by lactic acid bacteria (LAB) could be used in the development of functional fermented foods. In this work, four GABA-producing strains each of Lactococcus lactis and Streptococcus thermophilus were isolated from cowʼs milk, and their phenotypic, technological, and safety profiles were determined. Genome analysis provided genetic support for the majority of the analyzed traits. The operon harboring the glutamate decarboxylase gene (gadB) was chromosomally encoded in all strains and showed the same gene content and gene order as that reported, respectively, for L. lactis and S. thermophilus. In the latter species, the operon was flanked (as in most strains of this species) by complete or truncated copies of insertion sequences (IS), suggesting recent acquisition by horizontal gene transfer. The genomes of three L. lactis and two S. thermophilus strains showed a gene encoding a caseinolytic proteinase (PrtP in L. lactis and PrtS in S. thermophilus). These strains grew in milk forming a coagulum of good appearance and an appealing acidic flavor and taste. They also produced GABA from monosodium glutamate in this medium. Two L. lactis strains were identified as belonging to the biovar. diacetylactis, utilized citrate from milk and produced significant amounts of acetoin. None of the strains showed any noticeable antibiotic resistance, nor did their genomes harbor transferable antibiotic resistance genes, genes involved in toxicity, virulence, or pathogenicity. Altogether these results suggest all eight strains may be considered candidates for use as starter or components of mixed LAB cultures for the manufacture of GABA-enriched fermented dairy products.
Biology and Life Sciences, Food Science and Technology
Copyright:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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