The bifunctional enzymatic catalysis of maize waste for simultaneous production of arabinose and xylose

With the increase in environmental pollution, bio-manufacturing is gaining more attention. Plant sugars, including xylose and arabinose, could be utilized to produce bio-based chemicals. This study detected a putative gene encoding bifunctional xylosidase/arabinosidase in soil metagenome and isolated a bacterium, Sphingobacterium. The putative gene was expressed exogenously in Escherichia coli BL21 (DE3), and a bifunctional enzyme of approximately 35.9 kDa was obtained. The purified enzyme exhibited xylosidase and arabinosidase activities against p-nitrophenol-(3-D-xyloside and p-nitrophenol-alpha-L-arabinofuranoside. The optimum temperature for both enzymatic activities was 60 degrees C, whereas the pH optima for xylosidase and arabinosidase were 7.0 and 8.0, respectively. Using the bifunctional enzyme catalysis, 1.35 mg of xylose was obtained from 20 mg of maize stalk. Meanwhile, 2.238 mg of arabinose was obtained from 20 mg of maize cob. Two sugars co-production from biomass waste using the bifunctional xylosidase/arabinosidase showed promising applications in practice.