Technical Abstract: There is great interest in xylanases due to the wide variety of industrial applications for these enzymes. We cloned a xylanase gene (xyn8) from an environmental genomic DNA library. The encoded enzyme was predicted to be 399 amino acids with a molecular weight of 45.9 kD. Sequence analysis of the putative catalytic domain determined that the enzyme should be categorized as a glycosyl hydrolase family 8 member. The purified enzyme was thermolabile, had an activity temperature optimum of 20oC on native xylan substrate, and retained significant activity at lower temperatures. At 4oC, the apparent Km was 3.7 mg/ml, and the apparent kcat was 123 sec-1.