Synergistic xylan decomposition by a reducing-end xylose-releasing exo-oligoxylanase with other xylanolytic enzymes derived from Paenibacillus xylaniclasticus strain TW1

Paenibacillus xylaniclasticus strain TW1 is a promising tool for decomposing xylan-containing lignocellulosic biomass, since this strain possesses various genes encoding cellulolytic/hemicellulolytic enzymes. In this study, PxRex8A from the TW1 strain was found to be a reducing-end xylose-releasing exo-oligoxylanase of glycoside hydrolase family 8, which cleaves xylose from xylooligosacchrides of corn core xylan. In synergistic assay, the efficient decomposition of oat spelt xylan (OSX) and beech wood xylan was exemplified in the combination of endo β-1,4-xylanase (PxXyn11A) and PxRex8A from the TW1 strain in a molar ratio of 4:1. Furthermore, it was found that the addition of β-d-xylosidase/α-l-arabinofuranosidase (PxXyl43A) from this strain with PxXyn11A and PxRex8A achieved twice the amount of reducing sugars (1.1 mg/mL) against OSX after 24 hours compared to PxXyn11A alone (0.5 mg/mL). These results present that synergy effect of PxRex8A and PxXyl43A with PxXyn11A promotes xylan degradation into xylose.