Agricultural residues as potential substrates for production of xylanase from alkali-thermotolerant bacterial isolate

Xylanolytic Bacillus pumilus SS1 grew well at highly alkaline pH (9–11) and at moderately high temperature (25–55 °C) and successfully utilized wheat bran as the sole carbon source and produced considerable titer of xylanase. Maximum enzyme production occurred at medium pH 8 and at 45 °C. The enzyme purified (2.97-fold) with ammonium sulfate fractionation and carboxymethyl sephadex chromatography, showed molecular weight of 25 kDa, low Km (2.7 mg/ml) and reasonably good Vmax (36 μmol/mg/min). Enzyme showed maximum activity at pH 6–8, and at 40–50 °C. Enzyme was inhibited by HgCl2, CoCl2, MnSO4, MgCl2, phenylmethylsulphonylfluoride and CaCl2, while FeCl2 caused slight stimulation.