Overproduction of gamma-aminobutyric acid and increased antioxidant capacity by Lactiplantibacillus pentosus TEJ4 through optimization by response surface methodology

Lactic Acid bacteria (LAB) are the main producers of bioactive compounds (peptides, exopolysaccharides, antioxidant compounds, gamma-aminobutyric acid-GABA, etc.). Different strains produce at least one metabolite in high quantities as part of their metabolism, however, there are few reports of LAB with the capacity to produce two or more metabolites simultaneously. Due, the ability of 35 LAB strains previously isolated from dairy products, fermented beverages, and honey to produce gamma-aminobutyric acid (GABA) and the antioxidant capacity was determined. Based on analysis of variance and subsequent comparison of means, the Lactiplantibacillus pentosus strain was selected, and subsequently, using a Draper-Lin small composite design, the conditions of the culture medium (MRS broth) were optimized to achieve the highest production of GABA and increase the antioxidant capacity evaluated by the DPPH assay. The optimal conditions for obtaining 7.99 mg/mL of GABA were 100 mM glutamic acid, a pH of 6, a temperature of 40 °C, and 72 h of fermentation. To obtain the highest antioxidant capacity (6.87 µmol TE/mL), 200 mM glutamic acid and a pH of 4.0 were used. We reported an isolated strain of nondairy product (L. pentosus TEJ4) with the capacity to produce both bioactive, GABA, and antioxidants in a single fermentation process in a non-dairy defined medium, which is a feasible alternative to the normal process of producing bioactive compounds.