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: KX447660) 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 °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, Ca ²⁺ , Na ⁺ , Al ³⁺ , Zn ²⁺ , Cd ²⁺ , Mg ²⁺ , Ni ²⁺ , Cu ²⁺ had decreasing effect on enzyme activity, while enzyme activity had been protected against anions, especially HSO ^3- and HPO ₄ ^2- 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.
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