Purification And Expression Of A Novel Alkali-Stable Endoxylanase Xynh31

The endoxylanase Xynh31 was isolated and purified from the fermentation broth of Streptomyces sp. H31 strain by cation exchange chromatography. The optimal reaction pH of the xylanase was 7-9 and the maximum activity was determined at about 50 degrees C. It showed higher enzyme activity under alkaline conditions. Primers were designed using the conserved region of the glycoside hydrolase family 10, and the endoxylanase gene xynh31 was successfully cloned. The gene (1380 bp) encodes 459 amino acids. The results of BLAST analysis showed that the amino acid sequence was most similar to Xylanase A from the 10th family of Streptomyces Halstedii Jm8, but the highest identity was only 82%. E. coli BL21 (DE3) was used to express the gene, the maximum enzyme activity was 186.3 U/mL, and the specific activity was 628.4 U/mg. The enzyme meets the requirements of the paper industry and has good application prospects. (C) 2020 Friends Science Publishers