Xylanases from Streptomyces cyaneus: their production, purification and characterization

Abstract

SUMMARY: Streptomyces cyaneus produces extracellular xylanases in good yield when grown on ball-milled straw and xylan. Ball-milled straw induced nearly twice as much of these activities as did xylan, but phenolic substances released from the straw impeded purification of enzymes. Three extracellular xylanases, I, II and III, were identified in xylan-grown culture supernatants. Xylanases I and II were each purified to give single bands by SDS-PAGE. They had M r values of 37500 and 34000 respectively, while that of III was apparently 45000. pI values were 5.1 (I) and 5.3 (II) while pH and temperature optima, in 10 min assays, were 8.5, 72° (I) and 6.5, 65 °C (II).