Dahn K M, Davis B P, Pittman P E, Kenealy W R, Jeffries T W
Department of Biochemistry, University of Wisconsin, Madison, USA.
Appl Biochem Biotechnol. 1996 Spring;57-58:267-76. doi: 10.1007/978-1-4612-0223-3_24.
The Pichia stipitis xylose reductase gene (XYL1) was inserted into an autonomous plasmid that P. stipitis maintains in multicopy. The plasmid pXOR with the XYL1 insert or a control plasmid pJM6 without XYL1 was introduced into P. stipitis. When grown on xylose under aerobic conditions, the strain with pXOR had up to 1.8-fold higher xylose reductase (XOR) activity than the control strain. Oxygen limitation led to higher XOR activity in both experimental and control strains grown on xylose. However, the XOR activities of the two strains grown on xylose were similar under oxygen limitation. When grown on glucose under aerobic or oxygen-limited conditions, the experimental strain had XOR activity up to 10 times higher than that of the control strain. Ethanol production was not improved, but rather it decreased with the introduction of pXOR compared to the control, and this was attributed to nonspecific effects of the plasmid.
树干毕赤酵母木糖还原酶基因（XYL1）被插入到树干毕赤酵母以多拷贝形式维持的自主质粒中。将携带XYL1插入片段的质粒pXOR或不含XYL1的对照质粒pJM6导入树干毕赤酵母。在有氧条件下以木糖为培养基生长时，携带pXOR的菌株的木糖还原酶（XOR）活性比对照菌株高1.8倍。氧气限制导致在以木糖为培养基生长的实验菌株和对照菌株中XOR活性更高。然而，在氧气限制条件下，以木糖为培养基生长的两种菌株的XOR活性相似。在有氧或氧气限制条件下以葡萄糖为培养基生长时，实验菌株的XOR活性比对照菌株高10倍。乙醇产量没有提高，与对照相比，pXOR的导入反而使其降低，这归因于质粒的非特异性效应。
