Unité de Recherche Risques Microbiens (U2RM), Université de Caen Basse-Normandie Esplanade de la Paix, 14032 Caen, France.
Biotechnol Lett. 2012 Sep;34(9):1651-7. doi: 10.1007/s10529-012-0964-x. Epub 2012 May 25.
Genetically-modified Enterococcus faecalis has a potential of survival and can be used in ethanolic fermentations. Fermentation profiles of E. faecalis JH2-2 were assessed using glucose and lactose as carbon sources. Deletion of lactate dehydrogenase (ldh) genes increased the ethanol production from 0.25 to 0.82 g/l, which was further increased to 0.96 g/l by the insertion of a pyruvate decarboxylase (pdc) gene (from Sarcina ventriculi or Clostridium acetobutylicum) in place ldh1. When grown on lactose, the pdcSv and pdcCa showed 13.6 and 17.6 U mg(-1) of pdc specific activity, respectively. Highest activity (47 U mg(-1)) and ethanol concentration (2.3 g/l) were obtained with pdcCa using an expression plasmid. Formate and acetate were also produced in high quantities. Transcriptional analysis showed that aldehyde alcohol dehydrogenase gene was upregulated up to 16-fold. Further optimizations are required for higher ethanol production.
产肠球菌经过基因改造后具有生存能力，并可用于乙醇发酵。使用葡萄糖和乳糖作为碳源来评估肠球菌 JH2-2 的发酵特性。缺失乳酸脱氢酶（ldh）基因可将乙醇产量从 0.25 克/升提高到 0.82 克/升，进一步通过插入来自 Sarcina ventriculi 或 Clostridium acetobutylicum 的丙酮酸脱羧酶（pdc）基因（替代 ldh1）可将乙醇产量提高到 0.96 克/升。在乳糖上生长时，pdcSv 和 pdcCa 的丙酮酸脱羧酶比活性分别为 13.6 和 17.6 U mg(-1)。使用表达质粒时，pdcCa 可获得最高的酶活（47 U mg(-1)）和乙醇浓度（2.3 克/升）。还产生了大量的甲酸盐和乙酸盐。转录分析表明醛醇脱氢酶基因的表达上调了 16 倍。需要进一步优化以提高乙醇产量。
