Abstract:

Objective: To improve the productivity and reduce production costs of xylanase (XynB) and α-glucuronidase
(AguA) from Thermotoga maritima MSB8. Methods: Gene recombination technology was used to clone the XynB and AguA
genes into different BioBrick base vectors, thus constructing pET-20b-xynB-aguA and pET-28a-xynB-aguA. These plasmids
were then transformed into Escherichia coli JM109 (DE3), respectively, to induce the coexpression of the two enzymes
for hydrolysis of birch xylan and corncob. Results: After 8 hours of induction, the recombinant E. coli JM109 (DE3)/pET-
28a-xynB-aguA produced XynB and AguA with the yields reaching 7.6 and 0.5 U/mL in LB medium, respectively, which
were higher than those of E. coli JM109 (DE3)/pET-20b-xynB-aguA. In TB medium, XynB activity reached 10.27 U/mL
and AguA activity reached 1.5 U/mL. At 80 ℃, combination of both enzymes degraded birch xylan more thoroughly than
single xylanase, resulting in a higher content and purity of xylobiose in hydrolyzate. The amount of reducing sugar released
and electron microscopy observation revealed good degradation of corncob. Conclusions: Cloning and co-expression of
XynB and AguA from T. maritima are practicable and the recombinmant XynB and AguA have potential applications in
biotransformation, food industry, feed production and other areas.

Key words: xylanase, glucuronidase, coexpression, hydrolysis