Screening of the effect of xylose on the xylanase activity of the 225 XynA+clones. The xylanase activity in culture supernatants of each clone was measured in the presence and absence of xylose, and the activity ratio in the presence (+ xylose) as compared to the absence (−xylose) was calculated. A ratio (+xylose/−xylose) of 1.0 indicates no difference in the activity in the presence of xylose. Of the 225 clones, 69% (155 clones) showed lower activity in the presence of xylose and 4% (10 clones) showed an increased activity greater than 10% in the presence of xylose. See “Methods” section for further experimental details
