Biochemical characterization of tannase from Lactobacillus plantarum TG130 with potential for antinutritional tannins biodegradation

SAEZ GD; ZÁRATE G

Campinas

Simposio; 12 Simposio Latino Americano de Ciencia de Alimentos (SLACA 2017); 2017

Universidade de Campinhas

Tannins, a complex group of polyphenols widespread in vegetables used as food and feed, are usually considered as antinutritional factors since they inhibit digestive enzymes and affect the utilization of vitamins and minerals. Tannase (E.C. 3.1.1.20) catalyzes the hydrolysis of ester bonds in hydrolyzable tannins releasing glucose and gallic acid, a well-known antioxidant compound. This enzyme has been described in lactic acid bacteria conferring them the ability to metabolize tannins and release bioactive phenolic compounds. Then, our objective was to determine the optimal reaction conditions of the tannase of Lactobacillus plantarum TG130, a potential starter for legumes flours fermentation. Cell free extracts were obtained by mechanical disruption and tannase activity was assessed by a colorimetric rhodanine assay, specific for gallic acid detection. Optimum pH was determined in the range 3 to 9, whereas the effect of temperature on the specific activity was evaluated at optimum pH by assaying activity between 4°C and 65°C. Influence of cations (Na+, K+, Mg2+, Ca2+, Hg2+, Fe3+) and sulfhydryl group protecting reagents (DMSO and β-mercaptoethanol) were also evaluated. Specific degradation of tannic acid and methyl-gallate by non-proliferative suspensions was quantified by HPLC. Maximum tannase activity was obtained at 37°C and pH 6 (5.8 U/mL), whereas more than 80% of activity remained in the pH range 5.5?7 and no activity was detected below pH 4. Regarding cations, Mg2+ stimulated the enzyme whereas Hg+ significantly inhibited its activity. Tannase of L. plantarum TG30 hydrolyzed tannic acid more efficiently than methyl-gallate under the same reaction conditions, releasing 10.6 and 0.3 mmol/L of gallic acid from 20 mmol/L of substrates, respectively. L. plantarum TG130 could be considered as an interesting starter culture for vegetables fermentation with potential for the elimination of undesirable dietary tannins and the release of bioactive compounds relevant for human and animal health.