Purification and some properties of low-molecular-weight extreme halophilic xylanase from Chromohalobacter sp. TPSV 101

An extreme halophilic xylanase was purified from cultures of Chromohalobacter sp. TPSV 101 by ultrafiltration, hydroxylapatite and gel filtration chromatography. SDS-PAGE of the xylanase showed an apparent homogeneity and molecular weight of 15 kDa. The xylanase had maximum activity at pH 9.0 and 65 °C in the presence of 15–25% NaCl and was stable in the range of pH 7.0–9.0, temperature between 50 and 70 °C. The enzyme was stable at 50–65 °C for 1 h retaining 100% activity and by retaining 60% activity at 80 °C. The xylanase was completely inhibited by Hg2+ ions and was partially inhibited by Ca2+, Cu2+ and Pb2+ ions, whereas Zn2+, Mn2+ and Co2+ ions enhanced its activity. Both EGTA and EDTA enhanced its activity. It was active in solutions containing water-insoluble organic solvents and osmolytes. Kinetic experiments indicated that the enzyme had Km and Vmax values of 0.2 mg/ml and 1. 17 μmol/ml/min for oat spelt xylan. The major products of the oat spelt xylan hydrolysis were xylose and xylobiose; after prolonged incubation xylose was the major end product.

Oat spelt xylan was treated with xylanase under standard assay conditions for 24 h at 50 °C. Samples were removed and analyzed by HPLC for various xylooligosaccharides and found that xylose (X1) and xylobiose (X2) were the end products after 1 h (A) and 10 h (B) incubation.Figure optionsDownload as PowerPoint slideHighlights
► Novel and an extreme halophilic xylanase was purified from a halophilic bacteria, Chromohalobacter sp. TPSV 101 by employing different chromatography techniques.
► The purified xylanase was active at pH 9.0 and 65 °C in the presence of 15–25% NaCl concentration.
► The enzyme was stable in organic solvents and osmolytes in the absence of NaCl.