Highly efficient and stable enzymes are required for application in biotechnology, to meet the technical, environmental, and economic industrial demands. Xylanases are hemicellulolytic enzymes that degrade the heteroxylan constituent of the lignocellulosic plant cell wall. In this study, an acidic xylanase designated Pjxyn (pH 4.0) from Penicillium janthinellum was engineered by the introduction of a disulfide bridge. This strategy exploited the influence of the bridge on hydrolysis characteristics and enhanced hydrolysis was achieved. Three mutants [PjxynS(27)S(39), PjxynS(27)S(186), and PjxynS(39)S(186)] produced more xylose and xylobiose as hydrolysis products compared with the wild-type Pjxyn, when commercial xylans and lab-prepared water-insoluble corncob-xylan were used as the substrates, especial for the PjxynS(27)S(39) mutant, the content of xylose and xylobiose was 87.62% (using beechwood xylan) and 69.91% (using oat-spelt xylan) higher than that in the hydrolysis products of Pjxyn. Moreover, each mutant combined with the xylanase mutant T-XynFM effectively decreased the production of xylose with an optimum xylobiose yield. The findings demonstrate the potential industrial value of engineering xylanase to improve its hydrolytic properties and thermostability.
Keywords: Disulfide bridge; Hydrolytic characteristic; Xylanase.
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