National and Local United Engineering Lab of Metabolic Control Fermentation Technology, Tianjin University of Science and Technology, Tianjin, 300457, China.
Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin University of Science and Technology, Tianjin, 300457, China.
Appl Microbiol Biotechnol. 2018 Oct;102(20):8753-8762. doi: 10.1007/s00253-018-9316-7. Epub 2018 Aug 17.
In this study, a uridine and acetoin co-production pathway was designed and engineered in Bacillus subtilis for the first time. A positive correlation between acetoin and uridine production was observed and investigated. By disrupting acetoin reductase/2,3-butanediol dehydrogenasegenebdhA, the acetoin and uridine yield was increased while 2,3-butanediol formation was markedly reduced. Subsequent overexpression of the alsSD operon further improved acetoin yield and abolished acetate formation. After optimization of fermentation medium, key supplementation strategies of yeast extract and soybean meal hydrolysate were identified and applied to improve the co-production of uridine and acetoin. With a consumption of 290.33 g/L glycerol, the recombinant strain can accumulate 40.62 g/L uridine and 60.48 g/L acetoin during 48 h of fed-batch fermentation. The results indicate that simultaneous production of uridine and acetoin is an efficient strategy for balancing the carbon metabolism in engineered Bacillus subtilis. More importantly, co-production of value-added products is a possible way to improve the economics of uridine fermentation.
本研究首次在枯草芽孢杆菌中设计并构建了一个同时生产尿苷和乙酰丁酮的途径。观察到并研究了乙酰丁酮和尿苷生产之间的正相关关系。通过敲除乙酰丁酮还原酶/2,3-丁二醇脱氢酶基因 bdhA，乙酰丁酮和尿苷的产量增加，而 2,3-丁二醇的形成明显减少。随后过表达 alsSD 操纵子进一步提高了乙酰丁酮的产量并消除了乙酸的形成。优化发酵培养基后，确定并应用酵母提取物和豆粕水解物的关键补充策略，以提高尿苷和乙酰丁酮的共产量。在消耗 290.33 g/L 甘油的情况下，重组菌株在 48 h 的分批补料发酵中可以积累 40.62 g/L 尿苷和 60.48 g/L 乙酰丁酮。结果表明，同时生产尿苷和乙酰丁酮是平衡工程枯草芽孢杆菌碳代谢的有效策略。更重要的是，共生产有价值的产品可能是提高尿苷发酵经济性的一种途径。
