Glycoside Hydrolase Family 43 from Paenibacillus curdlanolyticus Strain B-6; An Accessory Enzyme to Enhance the Hydrolysis of Pretreated Rice Straw

Glycoside hydrolase family 43 (GH43) from Paenibacillus curdlanolyticus strain B-6 (Xyl43B6) was preformed heterologous expression in Escherichia coli . Enzymatic function determination revealed that Xyl43B6 exhibited trifunctional properties of α-L-arabinofuranosidase, β-xylosidase, and endo-xylanase. Xyl43B6 showed broad specificity of substrates on aryl-arabinoside, aryl-xylopyranoside, xylooligosaccharides, xylobiose, low branching xylan, and highly substituted arabinoxylan. Xylose liberation rate from xylooligosaccharides was higher than from xylobiose. However, trace amount of xylose was detected from highly substistuted rye flour arabinoxylan, indicating influence of chain length and substitution groups on xylose liberation efficiency of Xyl43B6. Moreover, co-hydrolysis of Xyl43B6 with GH10 endo-xylanase (Xyn10E) on pretreated rice straw revealed the boosting effect and increase in liberated reducing sugar as a result of Xyl43B6/endo-xylanase synergy. This report proposed new enzymatic properties of GH43 which showed the ability to enhance biomass biorefinery efficiency.