Production of Postbiotic Metabolites γ-Aminobutyric Acid (GABA) and Bacteriocin-Like Inhibitory Substances (BLIS) by Lactobacillus brevis C23 Co-culture in Coconut-Based Medium for Potential Psychobiotics and Food Preservatives

Abstract

Abstract Lactic acid bacteria (LAB) can produce γ-aminobutyric acid (GABA) with antioxidant properties and sedative effects when it binds to GABA receptor in human’s brain. LAB can also produce bacteriocin-like inhibitory substances (BLIS) with antimicrobial capabilities during carbohydrate fermentation. GABA and BLIS are natural compounds with potential health benefits and food preservation properties. Lactobacillus brevis C23 was co-cultured with three different LAB as inducers, which produced the highest GABA content and BLIS activity. They were cultured in various plant-based media to obtain an edible and better-tasting final product over commercially available media like MRS broth. A coconut-based medium with additives was optimized using Response Surface Methodology (RSM) to increase GABA and BLIS production. The optimized medium for maximum GABA production (3.22 ± 0.01mg/mL) and BLIS activity (84.40 ± 0.44%) was a 5.5% coconut medium containing 0.23% glucose, 1.44% Tween 20, 0.48% L-glutamic acid and 0.02% pyridoxine. Due to the presence of GABA, the cell-free supernatant (CFS) as a postbiotic showed a higher antioxidant activity than other food preservatives like nisin and potassium sorbate. Finally, a microbiological test on food samples showed that the postbiotic was more effective than other preservatives at combating the growth of LAB, molds, and coliform bacteria, making it a possible food preservative.