A pH-stable alkaline pectate lyase produced by the newly identified strain Bacillus altitudinis CAS-WZS-08

Abstract

Objectives: Thermal and pH stabilities are extremely important for the application of pectate lyase. In this study, we aimed to obtain a strain that is able to produce pectate lyase with good pH stability. Methods: In this study, screening for pectate lyase was performed using plate assays. Fermentation parameters for pectate lyase production were optimized utilizing a single variable optimization. To get insight into the pectate lyase, its enzyme property, purification, identification, and application were performed. Results: Bacillus altitudinis CAS-WZS-08, producing pectate lyase with good pH stability, was isolated. The optimal fermentation conditions of CAS-WZS-08 are 4 g/L pectin, 20 g/L yeast extract, 2% inoculum size, pH 7.0, and 33 °C, which the production of pectate lyase can reach up to 0.71 ± 0.001 U/mL. The optimal pH and temperature of the pectate lyase were 10.0 and 60 °C, respectively. Stored at 4 °C, the pectate lyase was able to keep its full enzyme activity for 24 h under a wide range of pH (4.0–10.0) condition. With pH 10.0, this pectate lyase was stable under 30-45 °C. In addition, it can be activated by Mn2+, Cu2+, Co2+, and Ca2+, while inhibited by Fe3+, Ba2+, and Mg2+. Later, the electrophoretic pure protein was acquired through ammonium sulfate precipitation, cation exchange column, and Sephadex G-75. Liquid chromatography tandem-mass spectrometry (LC/MS-MS) further confirmed that the purified protein was pectate lyase with a molecular weight of ∼ 40 kDa. At last, the result of pectate lyase in extracting apple juice demonstrated that it has an excellent juice extraction ability. Conclusion: This study provides an excellent pH-stable pectate lyase with good thermal stability that is a potential candidate for industrial applications.

Keywords

• Bacillus altitudinis
• Isolation
• pH-stable
• Pectate Lyase
• Thermal Stability