Optimisation on xylnase production from Aspergillus niger via statistical tool

Tan, Chia Zhi (2026) Optimisation on xylnase production from Aspergillus niger via statistical tool. Master dissertation/thesis, UTAR.

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Abstract

Nowadays, the biotechnology potential of xylanase enzyme in a range of industrial processes has drawn increasing attention. In the present study, the filamentous fungus Aspergillus niger was utilized for xylanase production inder submerged fermentation conditions. There are three main primary phases that will be discussed in the discussion section. Initial time-course analysis revealed that both optimum mycelial dry cell weight and xylanase activity peaked between Day 3 and Day 5, establishing this as the optimal fermentation period for enzyme productivity. To further enhance xylanase yield, ten variables were selected for screening using Plackett-Burman Design (PBD). Results from the PBD screening revealed that pH, temperature, xylan, NH₄NO₃, and K₂HPO₄ positively influenced xylanase production, while incubation time and CaCl₂ had negative effects. The significance of each variable was further verified using a Pareto chart, which graphically represented the standardized effects of different parameters on xylanase activity at a significance level of p < 0.05. According to the analysis, pH and CaCl₂ emerged as the most significant variables affecting xylanase production by A. niger. Therefore, optimisation via Central Composite Design (CCD) focused on these two key variables. Statistical analysis using ANOVA confirmed the robustness of the quadratic model generated, with a model F-value of 27.13 and a p-value of 0.0002, signifying strong model significance. The model also demonstrated excellent predictive accuracy, evidenced by an adjusted R² of 0.9159 and a predicted R² of 0.7198. Furthermore, the lack-of-fit test yielded a non-significant p-value of 0.3160, validating the model’s adequacy. Optimised conditions for maximum xylanase production were determined to be pH 6.5 and a CaCl₂ concentration of 0.931 g/L, with other parameters maintained at central levels. Validation experiments under these conditions yielded a maximum xylanase activity of 1.7569 U/mL, closely matching the model prediction.

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