Jeong K J, Park I Y, Kim M S, Kim S C
Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Taejon, Korea.
Appl Microbiol Biotechnol. 1998 Jul;50(1):113-8. doi: 10.1007/s002530051264.
To produce xylobiose from xylan, high-level expression of an endoxylanase gene from Bacillus sp. was carried out in Bacillus sabtilis DB104. A 1.62-kb SmaI DNA fragment, coding for an endoxylanase of Bacillus sp., was ligated into the Escherichia coli/B. subtilis shuttle vector pJH27 delta 88, producing pJHKJ4, which was subsequently transformed into B. subtilis DB104. A maximum endoxylanase activity of 105 U/ml was obtained from the supernatant of B. subtilis DB104 harboring pJHKJ4. The endoxylanase was purified to homogeneity by ion-exchange chromatography and the production profile of xylooligosaccharides from xylan by the endoxylanase was examined by HPLC with a carbohydrate analysis column. Xylobiose was the major product from xylan at 40 degrees C and its proportion in the xylan hydrolyzates increased with the reaction time; at 12 h, over 60% of the reaction products was xylobiose. These results suggest that xylobiose, which has a stimulatory effect on the selective growth of the intestinal bacterium Bifidobacterium, can be mass-produced effectively by the endoxylanase of Bacillus sp. cloned in B. subtilis.
为了从木聚糖生产木二糖，在枯草芽孢杆菌DB104中实现了来自芽孢杆菌属的一种内切木聚糖酶基因的高水平表达。将一个编码芽孢杆菌属内切木聚糖酶的1.62 kb SmaI DNA片段连接到大肠杆菌/枯草芽孢杆菌穿梭载体pJH27 delta 88中，构建出pJHKJ4，随后将其转化到枯草芽孢杆菌DB104中。从携带pJHKJ4的枯草芽孢杆菌DB104的上清液中获得了最高105 U/ml的内切木聚糖酶活性。通过离子交换色谱法将内切木聚糖酶纯化至同质，并使用碳水化合物分析柱通过高效液相色谱法检测该内切木聚糖酶从木聚糖产生低聚木糖的情况。在40℃下，木二糖是木聚糖的主要产物，并且其在木聚糖水解产物中的比例随反应时间增加；在12小时时，超过60%的反应产物是木二糖。这些结果表明，对肠道细菌双歧杆菌的选择性生长具有刺激作用的木二糖，可以通过克隆到枯草芽孢杆菌中的芽孢杆菌属内切木聚糖酶有效地大量生产。
