Xylooligosaccharides production by an immobilized recombinant fungal xylanase

Abstract

Xylooligosaccharides (XOS) are potential prebiotic ingredients for food industries, mainly obtained after xylan hydrolysis by endoxylanases. Enzyme immobilization possibilities recovery and reuse, in addition to improving its physical-chemical characteristics, such as stability and catalytic efficiency. This work aimed to immobilize the SM2 xylanase derived from the XynA gene from Orpinomyces sp. PC-2 and to evaluate its potential for XOS production. For this, SM2 xylanase was immobilized using the cross-linking methodology. The free and immobilized enzymes were characterized regarding the effect of pH, temperature, and thermostability. The cross-linked enzyme aggregate was evaluated for reuse and storage conditions and used for xylooligosaccharides production. Both free and immobilized SM2 xylanase showed maximal activity at 60 ºC. The immobilized enzyme was more active at acidic and neutral conditions, and the free enzyme showed greater activity at basic conditions. The half-life of the free and immobilized xylanase was 30 h and 216 h, respectively. In reuse tests, enzymatic activity increased with each cycle, and there was no statistical difference in the activity of SM2 xylanase aggregate stored at 4 and 25 ºC. After saccharification, xylobiose (0.903 g/L), xylotriose (0.487 g/L), and xylohexose (0.809 g/L) were detected. As a result, immobilization enhanced thermostability, shifted the pH of maximum activity to 5, facilitated reuse, and eliminated the need for refrigerated packaging. Finally, the xylooligosaccharides produced by the SM2 xylanase are known for their prebiotic role, providing potential application of the immobilized enzyme in the food industry.