Because it was reported that the xylanase production of Crypto-coccus sp. S-2 is strongly induced by xylose, xylanase activities of C. flavus GB-1 and GB-1-DMC1 were determined by measur-ing the amount of reduced sugar from beechwood xylan (SigmaAldrich Japan). However, no xylanase activity was detected in the xylose cultures of either strain.