New xylanolytic enzyme from Geobacillus galactosidasius BS61 from a geothermal resource in Turkey

In this study, isolation, conventional and molecular characterizations of ten thermophilic bacteria from Rize/Ayder were carried out. Xylanase from Geobacillus galactosidasius BS61 (GenBank number: 10(447660) was purified by acetone precipitation, Diethylaminoethyl-cellulose and Sephadex G-100 chromatographies. The xylanase of G. galactosidasius BS61 in clarifying fruit juice was also investigated. Enzyme was purified 29.80-fold with 75.18% yield; and molecular weight was determined as 78.15 kDa. The optimum temperature of xylanase was 60 degrees C. The enzyme activity was maintained fully after 24 h and over 50% after 168 h at pH 4.0-10.0, while optimum pH was 7.0. K-m and V-max for beech wood xylan were measured as 3.18 mg mL(-1), 123 U mg protein(-1). In addition, Ca2+, Na+, Al3+, Zn2+, Cd2+, Mg2+, Ni2+, Cu2+ had decreasing effect on enzyme activity, while enzyme activity had been protected against anions, especially HSO3- and HPO42- stimulated enzyme activity. Xylanase applications (with 15 U/mL enzyme activity) in orange and pomegranate juices were increased; and the sugar and turbidity amounts were reduced 17.36% +/- 1.18 and 30.52 +/- 1.23, respectively. These results indicated that the xylanase of G. galactosidasius BS61 has biotechnological potential in juice clarification due to its stability against metal ions, chemicals and high pH-values. (C) 2018 Elsevier B.V. All rights reserved.