The increase in hydrolytic activity towards corn silage water unextractable solids by supplementation of acetyl xylan esterase 1 (T. reesei, TrAxe1), belonging to carbohydrate esterase (CE) family 5, to an A. niger / T. emersonii enzyme preparation is presented. TrAxe1 was cloned and expressed in A niger. The hydrolytic activity of TrAxe1 was analysed with a p-nitrophenyl-acetate standard assay and by the measurement of the acetic acid released from neutral and acidic eucalyptus xylo-oligosaccharides. The activity obtained for TrAxe1 was compared to acetyl xylan esterases belonging to CE families 1, 5 and 16 from A. niger. High activities were obtained for the CE5 classified acetyl xylan esterases from T. reesei and A. niger. The data obtained confirm the suggested increase in hydrolytic activity by supplementation of CE5 classified acetyl xylan esterases to the (hemi)cellulolytic A. niger / T. emersonii preparation (Neumüller et al. 2014b).