Kinetic and Thermodynamic Study of Plantaricin IIA-1A5, a Bacteriocin Produced by Indonesian Probiotic Lactobacillus plantarum IIA-1A5

Background: Plantaricin IIA-1A5 is a bacteriocin produced by Lactobacillus plantarum IIA-1A5, a locally isolat-ed probiotic from Indonesia. Plantaricin IIA-1A5 exhibits antibacterial activity against wide spectrum of pathogenic bacte-ria, thus promising to be applied in various food products. Nevertheless, thermal stability of this bacteriocin remains to be fully investigated. Objective: This study aims to determine thermal stability of plantaricin IIA-1A5 through kinetic and thermodynamic param-eters. Method: To address, plantaricin IIA-1A5 was purified from Lactobacillus plantarum IIA-1A5, which was growth under whey media, using ammonium sulfate precipitation followed by ion-exchange chromatography. Purified plantaricin IIA-IA5 was then subjected to analysis of its bacteriocin activity. The thermal inactivation of bacteriocin from L. plantarum IIA-1A5 was calculated by incubating the bacteriocin at different temperatures ranging from 60-80 °C for 30 to 90 min, which was then used to calculate its kinetic and thermodynamic parameters. Results: The result showed the inactivation rates (k-value) were ranging from 0.008 to 0.013 min-1. Heat resistance of plantaricin IIA-1A5 (D-value) at constant heating temperature of 60, 65, 70, 75, and 80°C were 311.6, 305.9, 294.5, 198.9, and 180.2 min, which indicated a faster inactivation at higher temperatures. D-value sensitivity for temperature changes (z-value) was calculated to be 75.76°C. Further, thermodynamic analysis suggested that plantaricin IIA-1A5 is thermostable, with activation energy (Ea) of 29.02 kJ mol-1. Conclusion: This result showed that plantaricin IIA-1A5 is considerably more heat-stable than plantaricin members and promises to be applied in food industries where heat treatments are applied. Furthermore, a possible mechanism by which plantaricin IIA-1A5 maintains its stability was also discussed by referring to its thermodynamic parameters.