Bejar S, Belghith K, Ellouz R
Centre de Biotechnologie de Sfax.
Arch Inst Pasteur Tunis. 1994 Jul-Oct;71(3-4):407-17.
XylA gene of Streptomyces violaceoniger (Drocourt et coll. 1988) code for a D-xylose isomerase activity which is used as a D-glucose isomerase activity in large scale. This gene is a part of regulated region involved in xylose utilization (Marcel et coll. 1987). Sequence determination of this region enabled us to characterize xylB gene (Xylulose kinase activity) and xylX gene which is involved in xylA and xylB expression. In order to construct a new strain having a strong and constitutive glucose isomerase activity, a newly isolated strong streptomyces promoter (P1 promoter), has been cloned behind xylA gene. To avoid instability of plasmid and glucose-isomerase activity, the P1-xylA gene of S. violaceoniger has been integrated into the chromosome, using the integrative vector pTS55. The resultant CBS1 strain has four to five fold higher glucose-isomerase activity in absence of xylose compared to that of strain SV1 fully induced by xylose. In addition, specific glucose-isomerase activity of CBS1 strain increases in the secondary growth phase, in contrast to wild type and SV1 strains.
紫色链霉菌（Drocourt等人，1988年）的XylA基因编码一种D-木糖异构酶活性，该活性在大规模生产中用作D-葡萄糖异构酶活性。该基因是参与木糖利用的调控区域的一部分（Marcel等人，1987年）。对该区域的序列测定使我们能够鉴定出木糖B基因（木酮糖激酶活性）和参与XylA和木糖B表达的木糖X基因。为了构建一种具有强大且组成型葡萄糖异构酶活性的新菌株，一个新分离的强大链霉菌启动子（P1启动子）已被克隆到XylA基因的后面。为了避免质粒的不稳定性和葡萄糖异构酶活性，使用整合载体pTS55将紫色链霉菌的P1-XylA基因整合到染色体中。与完全由木糖诱导的SV1菌株相比，所得的CBS1菌株在没有木糖的情况下具有高四到五倍的葡萄糖异构酶活性。此外，与野生型和SV1菌株相比，CBS1菌株的特异性葡萄糖异构酶活性在二次生长阶段增加。
