College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, 30 Puzhunan Road, Nanjing 211816, Jiangsu, China.
Jiangsu Key Laboratory for Biomass-Based Energy and Enzyme Technology, Huaiyin Normal University, Huaian 223300, Jiangsu, China.
Int J Biol Macromol. 2018 Oct 1;117:377-384. doi: 10.1016/j.ijbiomac.2018.05.143. Epub 2018 May 22.
A GH30-8 endoxylanase was identified from an environmental Bacillus subtilis isolate following growth selection on aspen wood glucuronoxylan. The putative endoxylanase was cloned for protein expression and characterization in the Gram-positive protease deficient protein expression host B. subtilis WB800. The extracellular activity obtained was 55 U/mL, which was 14.5-fold higher than that obtained with the native species. The apparent molecular mass of BsXyn30 was estimated as 43 kDa by SDS-PAGE. BsXyn30 showed an optimal activity at pH 7.0 and 60 °C. Recombinant BsXyn30 displayed maximum activity against aspen wood xylan, followed by beechwood xylan but showed no catalytic activity on arabinose-substituted xylans. Analysis of hydrolyzed products of beechwood xylan by thin-layer chromatography and mass spectroscopy revealed the presence of xylooligosaccharides with a single methyl-glucuronic acid residue. BsXyn30 exhibited very low activity for hydrolysis xylotetraose and xylopentaose, but had no detectable activity against xylobiose and xylotriose. Using BsXyn30 as an additive in breadmaking, a decrease in water-holding capacity, an increase in dough expansion as well as improvements in volume and specific volume of the bread were recorded. Thus, the present study provided the basis for the application of GH30 xylanase in breadmaking.
一种 GH30-8 内切木聚糖酶是从一株环境枯草芽孢杆菌中筛选出来的，该菌株在杨木葡糖醛酸木聚糖上生长选择后产生。该内切木聚糖酶被克隆并在革兰氏阳性蛋白酶缺陷蛋白表达宿主枯草芽孢杆菌 WB800 中进行了蛋白表达和特性分析。获得的胞外活性为 55U/mL，比天然种提高了 14.5 倍。通过 SDS-PAGE 估计 BsXyn30 的表观分子量为 43kDa。BsXyn30 在 pH7.0 和 60°C 时表现出最佳活性。重组 BsXyn30 对杨木木聚糖表现出最大的活性，其次是山毛榉木聚糖，但对阿拉伯糖取代的木聚糖没有催化活性。通过薄层层析和质谱分析对山毛榉木聚糖水解产物的分析表明，存在带有单个甲基-葡萄糖醛酸残基的低聚木糖。BsXyn30 对水解木四糖和木五糖的活性非常低，但对木二糖和木三糖没有检测到活性。在面包制作中使用 BsXyn30 作为添加剂，记录到保水性降低、面团膨胀增加以及面包体积和比容的改善。因此，本研究为 GH30 木聚糖酶在面包制作中的应用提供了基础。
