Biochemical characterization of a GH10 xylanase from the anaerobic rumen fungus Anaeromyces robustus and application in bread making.

Anaeromyces robustus is an anaerobic rumen microorganism which can produce plant cell wall degrading enzymes. In this study, a new GH10 xylanase gene xylAr10 from A. robustus was identified, cloned and expressed in Pichia pastoris GS115. The recombinant protein ArXyn10 was characterized after being purified by Ni-NTA. The optimal pH and temperature of ArXyn10 was determined at 5.5 and 40 °C, respectively. ArXyn10 was stable at the pH range of 4.0-8.0, and could maintain high stability from 35 to 45 °C. The hydrolysis products released from beechwood xylan by ArXyn10 showed chromatographic mobility similar to xylobiose and xylotriose according to thin-layer chromatography analysis. It was shown that the addition of 7.5 mg of ArXyn10 in 100 g high-gluten wheat flour during bread making could increase the reducing sugar content by 10.80%, indicating that xylo-oligosaccharides were produced. With the addition of ArXyn10, the hardness and chewiness of the bread decreased and the quality was improved. The new discovered xylanase ArXyn10 have potential application prospect in bread making. © King Abdulaziz City for Science and Technology 2021.