초록
Our aim was to optimize the production of cellulase-free thermoactive xylanase by Aureobasidium pullulans CBS 135684 with statistical methodology based on experimental designs. Among eleven variables, the nutrient sources that had significant effect on xylanase production were corncob, <TEX>$(NH_4)_2SO_4$</TEX>, xylose, <TEX>$KH_2PO_4$</TEX> and tween 80, identified by the initial screening method of Plackett-Burman. The optimum concentrations of these five components were subsequently investigated using response surface methodology. The optimal concentrations (<TEX>$g{\cdot}l^{-1}$</TEX>) for maximum production of xylanase were corncob, 39.0; <TEX>$(NH_4)_2SO_4$</TEX>, 3.0; xylose, 1.8; <TEX>$KH_2PO_4$</TEX> 1.4; and tween 80, 1.4, respectively. An improved xylanase yield of <TEX>$8.74{\pm}0.84U{\cdot}ml^{-1}$</TEX> was obtained with optimized medium which is 2.1-fold higher production than previously obtained results (<TEX>$4.10{\pm}0.10U{\cdot}ml^{-1}$</TEX>) after 48 h of cultivation. In addition, the xylanase production under optimal condition reached <TEX>$10.09{\pm}0.27U{\cdot}ml^{-1}$</TEX> after 72 h of cultivation.