Properties of an alkaline-tolerant, thermostable xylanase from Streptomyces chartreusis L1105, suitable for xylooligosaccharide production.

An extracellular xylanase was purified to homogeneity from a culture of Streptomyces chartreusis L1105 by a 2-step method of ammonium sulfate precipitation and carboxymethyl sepharose fast-flow chromatography (CMSFF). The xylanase was purified by 6.86-fold, with a recovery yield of 31.96%. The purified xylanase appeared as a single protein band on SDS-PAGE with a molecular mass of about 34.2 kDa. The optimum temperature and pH of the purified xylanase activity were 70 °C and 7.2 respectively. The xylanase was more stable under alkaline conditions and retained more than 80% activity after 30 min incubation at pH 6 to 10. It also showed specific activity towards different xylans. Hydrolysis of oat-spelt and corn-cob xylans by the xylanase yielded xylobiose and xylotriose as principle products without the formation of xylose. These properties indicate that the purified xylanase may potentially be useful in biotechnological applications, such as xylooligosaccharide preparation. This is the first report about the purification and characterization of a xylanase from S. chartreusis.