Endo-1,4-beta-xylanase involved in the hydrolysis of xylan, a major structural heterogeneous polysaccharide found in plant biomass representing the second most abundant polysaccharide in the biosphere, after cellulose. Endohydrolysis of (1->4)-beta-D-xylosidic linkages in xylans. Glycan degradation; xylan degradation. Expressed in the presence of D-xylose under conditions of acidic ambient pH, probably under the regulation of the pacC transcription factor. Repressed in presence of glucose through the action of the creA transcription repressor. Belongs to the glycosyl hydrolase 11 (cellulase G) family.