Statistical Optimization of Media Components for Xylanase Production by Aspergillus spp. Using Solid State Fermentation and its Application in Fruit Juice Clarification

Abstract

Xylanases are enzymes that convert xylan into xylose, xylobiose, and xylotriose. The present study deals with the production and optimization of xylanase through Solid-State Fermentation (SSF) using different agricultural wastes by   Aspergillus spp. The Plackett Burman (PB) design was used to screen significant media components affecting the xylanase production. The carbon sources screened were wheat bran, rice bran, sugarcane bagasse, corn cob, and orange peel. The nitrogen sources screened were yeast extract, peptone, (NH4)2SO4, Na2NO3, and urea. Also, nine different salts such as KCl, MgSO4, Na2HPO4, CaCl2, FeSO4, ZnSO4, Na2CO3, KH2PO4, and NaH2PO4 which act as trace elements were screened. The results showed that wheat bran, yeast extract, Na2NO3 and KCl are the significant factors that affect xylanase production. A 33 Full Factorial Design (FFD) was performed to optimize the significant media components (wheat bran, KCl, yeast extract) obtained from PB design using Response Surface Methodology (RSM). Statistical analysis of results showed that wheat bran, KCl, yeast extract, and interaction between wheat bran and yeast extract were found to be significant. The optimum concentration of wheat bran, KCl, yeast extract was 8 g/L, 0.1 g/L and 3 g/L. The Partial purification of xylanase was carried out using ammonium salt precipitation and dialysis. Gel filtration chromatography was performed to optimize the elution time, which was found to be 6 minutes. Application of xylanase in orange juice clarification was studied at 40 °C, 50 °C, and 60 °C. The optimum temperature obtained was 60 ºC.