Purification and characterization of a pH and heat stable esterase from Geobacillus sp. TF17

Objective: To purify and characterize an esterase from a thermophilic bacterium, Geobacillus sp. TF17. Methods: The crude esterase was purified by using acetone precipitation and ion exchange choromatography methods and characterized. Results: The optimum temperature and pH of the enzyme were found to be 50°C and 7.5, respectively. The purified enzyme was extremely stable in the range of pH 4.0-9.0 after 72 hour incubation at 4°C. The thermal stability profile shows that this enzyme is stable in the range of 30-50°C after 72 h incubation. The Km and Vmax values for this esterase in the presence of p-nitrophenyl butyrate (pNPB) as substrate were found as 0.056 mM and 19.38 U/mg protein, respectively. The enzyme activity was inhibited more than about 60% in the presence of some organic solvents such as isopropanol and acetonitrile. Additionally, it was detected that some metal ions affect the enzyme activity at different ratio. Conclusion: An esterase was purified and characterized from Geobacillus sp. TF17. The pH and thermal stability of purified enzyme are quite high. The data obtained from this study show that the purified esterase has advantages for industrial or biotechnological applications in terms of especially its high thermal- and pH-stability.