Pirkov I, Albers E, Norbeck J, Larsson C
Department of Chemical and Biological Engineering-Molecular Biotechnology, Chalmers University of Technology, Kemivägen 10, 412 96 Göteborg, Sweden.
Metab Eng. 2008 Sep;10(5):276-80. doi: 10.1016/j.ymben.2008.06.006. Epub 2008 Jun 27.
The non-ethylene producing yeast, Saccharomyces cerevisiae, was transformed into an ethylene producer by introducing the ethylene forming enzyme from the plant pathogenic bacterium Pseudomonas syringae. Cultivation of the metabolically engineered strain was performed in well-controlled bioreactors as aerobic batch cultures with an on-line monitoring of ethylene production. The highest productivity was obtained during the respiro-fermentative growth on glucose but there was also a significant rate of formation during the subsequent phase of ethanol respiration. Furthermore, investigations were performed whether substitution of the original nitrogen source, NH(4)(+), for glutamate could improve productivity and yield of ethylene even more. The rationale being that one of the substrates for the enzyme is 2-oxoglutarate and this compound can be formed from glutamate in a single reaction. Indeed, there was a substantial improvement in the rate of production and the final yield of ethylene was almost three times higher when NH(4)(+) was replaced by glutamate.
通过导入植物病原菌丁香假单胞菌的乙烯形成酶，将不产生乙烯的酿酒酵母转化为能产生乙烯的酵母。在控制良好的生物反应器中对代谢工程菌株进行培养，作为需氧分批培养，并对乙烯产量进行在线监测。在以葡萄糖为底物进行呼吸发酵生长期间获得了最高的生产率，但在随后的乙醇呼吸阶段也有显著的生成速率。此外，还进行了研究，用谷氨酸替代原来的氮源NH₄⁺是否能进一步提高乙烯的生产率和产量。其基本原理是该酶的底物之一是2-氧代戊二酸，这种化合物可以由谷氨酸通过一步反应形成。实际上，当用谷氨酸替代NH₄⁺时，乙烯的生成速率有了显著提高，最终产量几乎提高了三倍。
