Production, purification and characterisation of a novel halostable xylanase from Bacillus sp. NTU‐06

Abstract

Bacillus sp. NTU‐06 was used to produce xylanase, which is an important industrial enzyme used in the pulp and paper industry. The enzyme was purified by fast protein liquid chromatography (FPLC) and had a molecular mass of 24 kDa. The enzyme was active over a concentration range of 0–20% sodium chloride in culture broth, although its activity was optimal in 5% sodium chloride. A salinity stability test showed that 43% of the enzyme activity was retained after 4 h in 20% sodium chloride. Xylanase activity was maximal at pH 8.0 and 40°C. The enzyme was somewhat thermostable, retaining 20% of the original activity after incubation at 70°C for 4 h. The xylanase had Km and Vmax values of 3.45 mg mL−1 and 387.3 µmol min−1mg−1, respectively. The deduced internal amino acid sequence of Bacillus sp. NTU‐06 xylanase resembled the sequence of beta‐1,4‐endoxylanase, which is a member of glycoside hydrolase family 11. Some of the novel characteristics that make this enzyme potentially effective in xylan biodegradation are discussed.