Purification and properties of an extra cellular xylanase enzyme of Clostridium strain SAIV

Abstract

An extracellular xylanase enzyme fraction A from a mesophilic Clostridium strain SAIV was purified by ammonium sulfate precipitation, Sephadex G-50 gel filtration and DEAE-Sephadex A-50 ion exchange. The xylanase exhibited a molecular weight of approximately 30,000 and it was stable upto 55 degrees C with an optimum temperature of 50 degrees C. It was most stable between pH 5-7, with an optimum pH of around 6. The Km value was 7.0 mg.xylan ml-1 and Vmax was 36 mumol.xylose liberated mg-1 min-1. Carboxymethyl cellulose, filter paper cellulose and 4-p-nitrophenyl beta-D-xylopyranoside were not hydrolysed. The specific activity of xylanase fraction A (9.8 U mg-1) is 2-10 fold higher than the specific activity of xylanase in other mesophilic, xylanolytic, obligate anaerobic bacteria. A minor fraction of xylanase activity designated as xylanase B was also obtained supporting the view that the multiplicity of xylanases is common in microorganisms.