Selection, heterologous production, and functional characterization of a thermostable xylanase from anoxybacillus for dough and bread quality enhancement

Abstract

Thermostable xylanases contribute to enhancing dough properties and bread quality in industrial baking. This study aimed to identify a high-yield thermophilic xylanase producer, optimize its heterologous expression, and evaluate its functional role in baking applications. Screening of 19 Anoxybacillus species identified A. bogrovensis as the highest xylanase producer. The xyn gene was cloned and expressed in Escherichia coli BL21, and the recombinant enzyme (iAboXYN) was purified using heat treatment, ion-exchange, and hydrophobic interaction chromatography. Biochemical characterization confirmed high thermal and pH stability, with over 50 % activity retained up to 80 °C and moderate stability observed at 90 °C, along with broad pH adaptability (5.0-8.5) and metal ion resistance. The enzyme's functional role in dough processing was assessed using a direct dose-response analysis, demonstrating improvements in dough stability, elasticity, and hydration efficiency while reducing mixing time and water absorption. Application in bread formulations led to enhanced loaf volume, improved crumb structure, and better texture, with sensory evaluation confirming superior quality. Preference ranking tests further validated the improved consumer perception of iAboXYN-treated bread. These findings establish iAboXYN as a functional biocatalyst for enzyme-assisted baking, offering a scalable approach to optimizing dough properties and improving bread quality.