合成乙醇重组乳杆菌的研究

Recombinant Lactobacilli for Ethanol Production

摘要:

将含有Zymomonas mobilis乙醇合成途径的关键酶基因的片段Ptac-pdc和Ptac-adhB，分别/同时接入pHY300PLK以及pBBR1MCS-5载体中，得到了pHY-PA、pBBR-PA等重组质粒，分别转化入几株乳杆菌。在42℃下进行乙醇发酵试验，结果表明：在Lactobacillus plantanum CICIM B0080中同时引入基因pdc、adhB有效地将碳代谢流导向了产乙醇方向，重组菌B0080 (pHY-PA)发酵6.7%葡萄糖60h分别产生0.4% (V/V) 乙醇，为原始菌B0080的67倍；而将pdc、adhB基因同时引入L.amylovorus B0112和L.acidophilus B0068，能检测到相当于原始菌2倍的乙醇产出。在重组菌发酵过程中，仍有大量的乳酸产出，在引入产乙醇基因的同时敲除乳酸脱氢酶基因，将有可能使乳杆菌的代谢流向更有效地转向产乙醇途径。

Abstract:

Recombinant plasmids pHY-PA, pBBR-PA were constructed in which genes pdc and adhB were placed under the control of tac promoter, respectively, and had successfully expressed in Escherichia coli. Then these recombinant plasmids were electroporated into Lactobacillus strains for ethanol production. Preliminary ethanol fermentation using these Lactobacillus strains and their recombinants was carried out using 42℃ as fermentation temperature. The results indicated that introducing pdc and adhB, ethanologenic pathway was successfully constructed in L.plantanum CICIM B0080. 0.4% (V/V) ethanol was detected at the end of fermentation with 6.7% glucose, and that is 67-fold as the wild-type B0080. Two-fold of ethanol production was detected in L.amylovorus B0112 (pHY-PA) and L.acidophilus B0068 (pBBR-PA). Introducing both pdc and adhB, and meanwhile knock-outing the lactate dehydrogrnase gene may better convert carbon flux to ethanologenic direction.