Optimization of xylanase production from Aspergillus Spp. hau-f-6 using plackett burman screening design and path of steepest ascent in submerged fermentation

Xylanases are mainly responsible for the hydrolysis of β-1,4 bonds in plant xylan, the main component of hemicelluloses. In the present investigation, statistical designs were successfully used to optimize the fermentation parameters for enhanced xylanase production from Aspergillus spp. HAU-F-6 in submerged cultivation. The initial carbon screening test found wheat bran as the best carbon source to replace the expensive xylan in the fermentation medium. In Plackett-Burman Screening Design (PBSD), eleven independent variables viz. wheat bran, KH₂PO₄, tween-80, calcium chloride, urea, yeast extract, ammonium sulphate, peptone, sodium carbonate, ferrous sulphate and magnesium sulphate were selected. Supplementation of high levels of wheat bran, tween-80, yeast extract, ammonium sulphate, MgSO₄, and FeSO₄ in the growth medium positively affected the xylanase production. Contrarily, KH₂PO₄, calcium chloride, urea, peptone and sodium carbonate at their low concentrations of 0.5, 0.25, 1.0, 3.0 and 0.5 g/l, respectively resulted in higher xylanase production. Yeast extract, ammonium sulphate, MgSO₄ and wheat bran had significant positive effects at 10% level. Analysis of variance of PBSD showed the model used for prediction to be significant (p<0.10). The levels of CaCl₂, yeast extract and ammonium sulphate were further optimized using the Path of Steepest Ascent (POSA). Compared with the basal medium, an overall 9.76 fold higher enzyme activity was achieved from the model of the optimized medium, and xylanase activity was found to be 20.8 IU/ml.