Dear Chornaraj Vs,

Go through the attached paper..

There are many good papers describing  how to isolate xylanase-producing organism. If you want to test whether it only produces  xylanase, pure culture and subsequent experiment are needed.

prepare a minimal media containing oat spelt xylan or birchwood xylan (1 %) as carbon source. carry over a streak or drop plate technique for the isolate to be screened and then after 48-72 h of incubation flood the plates with congored (1 %) and incubate it for 15 mts and then wash it off the congored using 1 M NaCl after incubation for 15 mts. clear halo zone around the colony indicate the xylanase production (xylan hydrolyis) by the microorganism