Multi-efficient thermostable endoxylanase from Bacillus velezensis AG20 and its production of xylooligosaccharides as efficient prebiotics with anticancer activity

摘要

In this study, we have unveiled the novel potential of xylanase production by Bacillus velezensis, previously known only for its PGPR traits. According to our investigations, Bacillus velezensis AG20 produced extracellular xylanase with a fold purification of 5.3 and a yield of 21 %. The purified xylanase (45 kDa) aptly cleaved linear 8-(1 - 4)-xylan with a maximum velocity of 21.0 +/- 3.0 U/mL, a turnover of 1.75/s, and a catalytic cycle of 0.571 at optimum pH 7. The temperature of 50 degrees C was found optimum for enzyme activity. Purified endoxylanase was thermostable and retained its significant residual activities at 50 degrees C and 60 degrees C. Metal cations such as Ca2+ and Mg2+ enhanced the substrate catalysis up to 1.5 fold. The purified endoxylanase also demonstrated multisubstrate hydrolyzing properties. However, the enzymatic hydrolysis of sugarcane bagasse produced xylooligosaccharides (XOS), including xylobiose, xylotriose, and xylotetrose. The mixture of released XOS has profound stability in gastric juice, intestinal fluid, and alpha-amylase and facilitates probiotic bacteria Bifidobacterium. The mixed XOS (300 mu g/mL) significantly inhibited the HT-29 and Caco-2 cell proliferation by 90 % and 75 %, respectively, at 48 h. The possible mechanism of XOS uptake through the BIAXP receptor of Bifidobacterium has been contemplated and established using the caver analysis, Molecular Dynamics (MD) simulation, and Density Functional Theory (DFT) studies. Thus, here we reveal the utility of this novel bacterial strain in industries as high-temperature catalysts.