Efficient secretion of xylanase in Escherichia coli for production of prebiotic xylooligosaccharides

The N-terminal 20 amino acid of Lactobacillus amylovorus feruloyl esterase (N20) was used as a signal peptide for f usion expression with a novel xylanase Xyl derived from Bacillus paralicheniformis. Results showed that N20-Xyl could be effectively secreted out of E. coli BL21(DE3) cells. Enzymatic characterization indicated that Xyl and N20-Xyl exhibited similar properties with the optimal pH of 8.0 and temperature of 50 C. Furthermore, xylooligosaccharides were prepared through simultaneous xylanase secretion and xylan degradation by using E. coli. The final extracellular reducing sugar content reached 8.79 +/- 0.10 g/L based on 40 g/L xylan, and the main products were xylobiose, xylotriose, and xylotetraose. Moreover, it was found that Levilactobacillus brevis 217-168, Enterococcus faecium 217-169, Pediococcus acidilactici 217-112, and Weissella confusa 217-162 could efficiently utilize these xylooligosaccharides for growth. Therefore, this study provided a method for the pro-duction of prebiotic xylooligosaccharides via simultaneous fermentation by using E. coli.

Automated summary

In this study, the N-terminal 20 amino acid of Lactobacillus amylovorus feruloyl esterase (N20) was used as a signal peptide to fuse with a xylanase Xyl derived from Bacillus paralicheniformis. The fused protein N20-Xyl could be effectively secreted from E. coli BL21(DE3) cells. Enzymatic characterization showed that Xyl and N20-Xyl had similar properties with optimal pH of 8.0 and temperature of 50°C. Xylooligosaccharides were prepared through simultaneous xylanase secretion and xylan degradation by using E. coli, with the main products being xylobiose, xylotriose, and xylotetraose. Moreover, several Lactobacillus strains were found to efficiently utilize these xylooligosaccharides for growth.