Economical and higher production of cellulase-free xylanase(s) is needed for their wider application in paper and pulp industries. For enzyme production at industrial scale, the growth medium contributes up to 40% of the total production cost. The large quantity of xylan-rich corn cob biomass generated worldwide from corn-processing industries can be used as a cheaper substrate for the production of xylanase. In the present study, the optimization of the production of xylanase by Aspergillus niger DX-23 was studied under solid-state fermentation (SSF) using the Plackett-Burman design (PBD) and response surface methodology (RSM). Among eleven factors investigated (each at two levels) in PBD, corn cob powder, KH₂PO₄, yeast extract, Tween 20, FeSO₄.7H₂O, MgSO₄.7H₂O, CoCl₂, MnSO₄.H₂O and ZnSO₄∙H₂O significantly (p < 0.05) influenced the production of xylanase by A. niger DX-23. Subsequently, RSM involving central composite design (CCD) was adopted to determine the optimum levels of corn cob powder, NaNO₃ and KH₂PO₄ and FeSO₄. According to ANOVA for xylanase production, for CCD-I although the quadratic model developed was significant (p = 0.026465), the model also showed significant lack-of-fit (p = 0.004056) and low predicted R². Hence, CCD-II which included two variables, i.e. corn cob powder and NaNO₃, was carried out. For CCD-II, the quadratic model developed was significant (p = 0.007753), lack-of-fit value was non-significant (p = 0.677031) and the predicted R² was 0.51. Based on CCD-II, the optimum levels of corn cob powder and NaNO₃ in the medium were found to be 150.0 g/l and 5.1 g/l, respectively. To confirm the accuracy of the model, when xylanase production by A. niger DX-23 was studied in an optimized medium under SSF conditions, the xylanase yield reached 306.12 ± 7.4 U/g after 10 days of growth which agreed fairly well with the predicted value (290.15 U/g). Hence, the quadratic model created could be considered to be accurate and reliable for predicting the production of xylanase by A. niger DX-23 under SSF. Moreover, when the effect of pH and inoculum concentration on xylanase production was investigated, in an optimized medium, the maximum production of xylanase was obtained at pH 5.0 and at an inoculum level of 5.0 × 10⁶ spores/ml. When the time course of the fermentation was followed, A. niger DX-23 produced maximum xylanase (496.9 ± 3.0 U/g) after 6 days of fermentation.

为了在造纸和纸浆工业中广泛应用，需要经济且更高产量的无纤维素酶木聚糖酶。对于工业规模的酶生产，生长培养基贡献了总生产成本的40％。全世界从玉米加工工业中产生的大量富含木聚糖的玉米芯生物量可以用作生产木聚糖酶的较便宜的底物。在本研究中，使用Plackett-Burman设计（PBD）和响应面方法（RSM）在固态发酵（SSF）下研究了黑曲霉DX-23对木聚糖酶生产的优化。在PBD中调查的11个因素中（每个级别有两个），玉米芯粉，KH ₂ PO ₄，酵母提取物，Tween 20，FeSO ₄.7H ₂ O，MgSO ₄ .7H ₂ O，CoCl ₂，MnSO ₄ .H ₂ O和ZnSO ₄ ∙H ₂ O显着（p <0.05）影响黑曲霉DX-23生成木聚糖酶。随后，采用涉及中央复合设计（CCD）的RSM来确定玉米芯粉，NaNO ₃和KH ₂ PO ₄和FeSO ₄的最佳含量。根据用于木聚糖酶生产的ANOVA，对于CCD-I，尽管开发的二次模型很明显（p = 0.026465），但该模型也显示出严重的不拟合（p = 0.004056）和较低的预测R ²。因此，进行了包括玉米芯粉和NaNO ₃在内的两个变量的CCD-II 。对于CCD-II，建立的二次模型是显着的（p = 0.007753），失配值是不重要的（p = 0.677031），预测的R ²是0.51。基于CCD-II，发现培养基中玉米芯粉和NaNO ₃的最佳含量分别为150.0 g / l和5.1 g / l。为了确认模型的准确性，当黑曲霉生产木聚糖酶时在SSF条件下的优化培养基中研究了DX-23，木聚糖酶在生长10天后的产量达到306.12±7.4 U / g，与预测值（290.15 U / g）相当吻合。因此，创建的二次模型可以被认为是准确和可靠的，以预测在SSF下黑曲霉DX-23的木聚糖酶产生。此外，当研究pH和接种物浓度对木聚糖酶产生的影响时，在优化的培养基中，在pH 5.0和接种物水平为5.0×10 ⁶孢子/ ml时，木聚糖酶的产量最高。当遵循发酵的时间过程时，在发酵6天后，黑曲霉DX-23产生最大的木聚糖酶（496.9±3.0U / g）。