Identification and Characterization of a Novel Endo-β-1,4-Xylanase from Streptomyces sp. T7 and Its Application in Xylo-Oligosaccharide Production

Molecules. 2022 Apr 13;27(8):2516. doi: 10.3390/molecules27082516.

Abstract

A xylanase-producing strain, identified as Streptomyces sp. T7, was isolated from soil by our lab. The endo-β-1,4-xylanase (xynST7) gene was found in the genome sequence of strain T7, which was cloned and expressed in Escherichia coli. XynST7 belonged to the glycoside hydrolase family 10, with a molecular mass of approximately 47 kDa. The optimum pH and temperature of XynST7 were pH 6.0 and 60 °C, respectively, and it showed wide pH and temperature adaptability and stability, retaining more than half of its enzyme activity between pH 5.0 and 11.0 below 80 °C. XynST7 showed only endo-β-1,4-xylanase activity without cellulase- or β-xylosidase activity, and it showed maximal hydrolysis for corncob xylan in all the test substrates. Then, XynST7 was used for the production of xylo-oligosaccharides (XOSs) by hydrolyzing xylan extracted from raw corncobs. The maximum yield of the XOS was 8.61 ± 0.13 mg/mL using 15 U/mL of XynST7 and 1.5% corncob xylan after 10 h of incubation at 60 °C. The resulting hydrolysate products mainly consisted of xylobiose and xylotriose. These data indicated that XynST7 might by a promising tool for various industrial applications.

Keywords: endo-β-1,4-xylanase; expression; xylo-oligosaccharides.

MeSH terms

  • Endo-1,4-beta Xylanases / metabolism
  • Enzyme Stability
  • Escherichia coli / genetics
  • Escherichia coli / metabolism
  • Hydrogen-Ion Concentration
  • Hydrolysis
  • Oligosaccharides
  • Streptomyces* / metabolism
  • Xylans*

Substances

  • Oligosaccharides
  • Xylans
  • Endo-1,4-beta Xylanases