Achieving efficient co-expression of endo- β-1,4-xylanase and α-arabinofuranosidase in Trichoderma reesei and application in the production of arabino-xylo-oligosaccharides.

A feasible process for the degradation of psyllium arabinoxylan (AX) to arabino-xylo-oligosaccharides (AXOS) is proposed. A suspension of Trichoderma reesei mycelium suspension, acting on seed husks of psyllium as a carbon source, produced endo-β-1,4-xylanase (xynTR) and α-arabinofuranosidase (abfTR), with enzymatic activity levels of 11.09 ± 0.09 and 11.46 ± 0.16 IU/mL, respectively. AX derived from psyllium husk was hydrolyzed successfully through a fractional precipitation of 50 % (NH)SO with xynTR and abfTR at a dosage of 200 and 157.84 IU per gram of substrate, respectively. The yield of AXOS was 30.95 % ± 0.50 %. The process reported here addresses the problem of the refractory hydrolysis of AX with multi-branched chain structure. The addition of abfTR in the AX hydrolysis system resulted in the removal of the arabinose substituents from the xylan backbone of AX, thus alleviating the steric hindrance of xynTR hydrolysis.