An ammonium sulfate sensitive endoxylanase produced by Streptomyces.

ABSTRACT

Streptomyces sp. CSWu2 was newly isolated and identified from Korean soil. In culture medium, the strain produced a highly active endoxylanase (Xynwu2), which was purified to homogeneity by a single-step chromatography on Poros-HQ. The xylanase was ~38 kDa and its activity was maximal at 65 °C and pH 11.0. It was stable up to 60 °C and from pH 8.0 to 12.0, and its activity was slightly enhanced by nonionic detergents, but inhibited by EDTA, EGTA, and divalent metal ions. Intriguingly, Xynwu2 was highly sensitive to ammonium sulfate, but its completely suppressed activity was recovered by desalting out. Xynwu2 produced xylose and xylobiose as principal end products from xylan, suggesting an endoxylanase nature. Importantly, scanning electron microscopy showed Xynwu2 efficiently degraded corncobs, an agro-industrial waste material. We believe that Xynwu2 is a potential candidate for converting lignocellulosic waste material into simple sugars which could be used to produce bioethanol and other value-added products.