中文摘要：

对吐温-80提高L-赖氨酸产量的分子机制进行探究。以钝齿棒杆菌MT-M4Δpro B为出发菌株,在菌株生长至对数初期36 h时,添加5 mg/m L吐温-80进行摇瓶发酵,通过反转录实时荧光定量聚合酶链式反应（reverse translate？real-time？fluorescence？quantitative？polymerase？chain？reaction,RT-q PCR）监控相关基因的转录水平、胞内的还原型烟酰胺腺嘌呤二核苷酸磷酸（nicotinamide adenine dinucleotide phosphate reduced form,NADPH）水平及α-酮戊二酸脱氢酶复合物（α-oxoglutarate dehydrogenase complex,ODHC）的活力。摇瓶发酵结果表明,添加吐温-80使L-赖氨酸产量提高了215%;RT-q PCR结果表明,编码ODHC的基因odh A、suc B和lpd A、参与ODHC调控的基因pkn G、dts R和ppp以及合成NADPH的磷酸戊糖途径基因zwf的转录水平均发生了变化,其中odh A、suc B、lpd A、pkn G及dts R1基因分别发生了上调,ppp基因下调,相应ODHC活力提高了32.9%;zwf基因上调了17.6倍,相应胞内NADPH水平提高了137%。因此,在对数生长初期36 h添加吐温-80具有双重功效,既提高了ODHC的表达又使NADPH积累,从而诱导L-赖氨酸的高产。

英文摘要：

The current work aimed to investigate the molecular mechanisms of Tween-80 for triggering L-lysine overproduction by Corynebacterium crenatum. L-lysine yield was increased by approximately 215% with the addition of Tween-80 in C. crenatum. By using reverse translate real-time fluorescence quantitative polymerase chain reaction, we determined that the transcriptional levels of odh A, suc B and lpd A, which encode three subunits of 2-oxoglutarate dehydrogenase complex（ODHC）, were up-regulated; pkn G and dts R1 involved in the signal transduction pathway for ODHC regulation were up-regulated but ppp was down-regulated. As a result, ODHC-specific activity was increased by 32.9%. Furthermore, the transcriptional level of zwf involved in the pentose phosphate pathway was increased by 17.6 folds; thus, intracellular NADPH level was enhanced by 137% in C. crenatum triggered by Tween-80. The addition of Tween-80 to the fermentation medium at the early exponential growth phase induced a bifunctional mechanism for L-lysine overproduction by improving ODHC activity and NADPH supply in C. crenatum.