CEB-Centre of Biological Engineering, Universidade do Minho, Campus de Gualtar, 4710-057 Braga, Portugal.
QOPNA, Departamento de Química, Universidade de Aveiro, 3810-193 Aveiro, Portugal.
Carbohydr Polym. 2018 Nov 1;199:546-554. doi: 10.1016/j.carbpol.2018.07.017. Epub 2018 Jul 7.
Brewers' spent grain (BSG) is an inexpensive and abundant brewery by-product that can be used to produce prebiotic arabino-xylooligosaccharides (AXOS). In this study, Bacillus subtilis 3610 was used, for the first time, to produce AXOS through direct fermentation of BSG. Additionally, the microorganism was genetically modified to improve the AXOS production. The xylanase gene xyn2 from Trichoderma reesei coupled with a secretion tag endogenous to B. subtilis was cloned in pDR111 and integrated into its chromosome. After optimization by experimental design, AXOS with a degree of polymerization ranging from 2 to 6 were obtained. The maximum production yield expressed in xylose equivalents per amount of BSG (54.2 ± 1.1 mg/g) represents an increase of 33% comparing to the wild type. When compared with the enzymatic hydrolysis process, single-step fermentation with B. subtilis proved to be a very promising low-cost strategy for the simultaneous production of AXOS and valorization of BSG.
啤酒糟（BSG）是一种廉价且丰富的啤酒厂副产品，可以用来生产益生元阿拉伯木聚糖低聚糖（AXOS）。本研究首次利用枯草芽孢杆菌 3610 通过 BSG 的直接发酵生产 AXOS。此外，还对微生物进行了遗传改造以提高 AXOS 的产量。将里氏木霉的木聚糖酶基因 xyn2 与枯草芽孢杆菌内源性的分泌标签连接到 pDR111 中，并整合到其染色体上。通过实验设计进行优化后，得到聚合度为 2 至 6 的 AXOS。以每单位 BSG（54.2±1.1mg/g）的木糖当量表示的最大产率与野生型相比增加了 33%。与酶水解工艺相比，枯草芽孢杆菌的一步发酵法被证明是一种很有前途的低成本策略，可同时生产 AXOS 和利用 BSG。
