Modification and Optimization of Low-cost Medium for Recombinant Alkalothermophilic Xylanase Production from Pichia pastoris KM71

Abstract

Xylanase is an enzyme that can degrade xylan into xylooligosaccharides by cleaving to 1, 4-β-D-xylosidic bonds and has high potential in industrial applications. In the previous study, recombinant Pichia pastoris via pPICZ-alpha vector has been constructed, and the yeast produced xylanase originally came from Bacillus halodurans CM1. Recombinant xylanase production from Pichia pastoris using standard medium has been conducted. However, if a larger scale has to be done using this standard medium, it will not be feasible, due to the high cost of the standard medium. Therefore, in this study, the composition of standard media was substituted with a low-cost substrate. Modification of production medium was conducted by replacing pure glycerol with technical glycerol as carbon source, while peptone and yeast extract as organic nitrogen source were substituted with soybean hydrolysate (18% (w/v) total N content) and rice bran (14.63% (w/v) total N content), respectively, and ammonium sulphate as an additional source of inorganic nitrogen. Use of technical glycerol 1% (v/v) and a mixture of 15 g/100 mL soybean hydrolysate, rice bran hydrolysate 30g /100 mL, and 2.5% (w/v) ammonium sulphate were found to be the most suitable medium that gave high volumetric activity (1383.9 U/mL), specific activity (861.7 U/mg), protein concentration (1.606 mg/mL), and dry cell weight (43.3g/L).