Department of Food Science, Cornell Universty, Ithaca, N. Y. 14853.
Biotechnol Prog. 1986 Sep;2(3):140-4. doi: 10.1002/btpr.5420020308.
The xylose isomerase (xylA) structural gene was cloned under the control of the tac promoter and expressed in a xyl(+) E. coli strain. Xylose isomerase accounted for approximately 28% of the total cell protein when this tac-xylA fusion was induced with isopropylthio beta-D-galactopyranoside. Hyperexpression of the xylA gene inhibited xylose utilization. E. coli carrying this tac-xylA fusion was encapsulated in calcium-alginate beads and used to isomerase xylose in a column reactor. Conversion of xylose to xylulose was 3-4% with a residence time in the column of 2 minutes and a maximum of 12% upon recycling.
木糖异构酶（xylA）结构基因在 tac 启动子的控制下被克隆，并在木糖（+）大肠杆菌菌株中表达。当用异丙基硫代-β-D-半乳糖吡喃糖苷诱导时，木糖异构酶约占总细胞蛋白的 28%。xylA 基因的过表达抑制了木糖的利用。携带该 tac-xylA 融合基因的大肠杆菌被包埋在海藻酸钙珠中，并用于在柱式反应器中使木糖异构化。在柱内停留时间为 2 分钟时，木糖转化为木酮糖的转化率为 3-4%，循环时最大转化率为 12%。
