B. circulans WL-12 secretes 2 endo-.beta.-D-xylanases (A and B, respectively) (EC 3.2.1.8) and 1 .beta.-D-xylosidase (EC 3.2.1.37) when cultured in liquid media with xylan as the sole C source. Xylanases A and B were partially characterized with respect to their main physicochemical parameters and .beta.-D-xylosidase to a lesser extent on account of its low stability. Both endo-.beta.-D-xylanase A and .beta.-D-xylosidase were adsorbed on DEAE-Biogel A, had similar MW (.apprx. 85,000), and had optimal pH values of 5.5-7; however, different isoelectric points (4.5 for .beta.-D-xylanase A and 4.7 for .beta.-D-xylosidase) and different mobilities in polyacrylamide gel electrophoresis were exhibited. The apparent Km for .beta.-D-xylanase A was 8 mg/ml and the hydrolysis products produced were xylose, xylobiose, xylotriose and xylotetraose. The 2nd end-.beta.-D-xylanase (.beta.-D-xylanase B) bound to CM-Biogel A and exhibited a MW of approximately 15,000 and an optimum pH value in the range of 5.5-7. The isoelectric point was 9.1 and the apparent Km was 4 mg/ml. The hydrolysis products produced by this enzyme were xylobiose, xylotriose and xylotetraose, but never xylose. In polyacrylamide gel electrophoresis at pH 8 the enzyme moved towards the negative electrode.