Gene cloning, expression, immobilization and characterization of endo-xylanase from Geobacillus sp. TF16 and investigation of its industrial applications

Abstract

The xylanase gene (xynTF16) from a thermophilic bacterium Geobacillus sp. TF16 was cloned into pET-28a(+) vector and expressed in Escherichia coli BL21(DE3)pLysS. Recombinant enzyme (GsXynTF16) was purified 52-fold by nickel affinity chromatography, and determined as a single band 39.8kDa on SDS-PAGE with a specific activity of 246U/mg protein. The recombinant enzyme was immobilized on chitosan with a yield of 85.6%. The enzyme showed the highest activity towards xylan. The immobilized enzyme displayed an increase in optimum temperature from 55 to 65°C in comparison with free enzyme. While the free enzyme was optimally active at pH 8.5, immobilized enzyme showed higher activity in the pH range 6.0–8.5. Thermal and pH stability of immobilized enzyme was determined to be higher than that of the free enzyme. Immobilized xylanase could be reused for 6 consecutive cycles retaining 80% of its initial activity. It was also found to be effective in releasing the reducing sugar from juice and poultry feed and oven spring in bakery. These results suggest that this study provides an alternative xylanase enzyme with enhanced properties.