초록
The ethanol production by recombinant Escherichia coli introducing of pyruvate decarboxylase (pdc) and alcohol dehydrogenase (adhB) from Zymomonas mobilis was investigated under aerobic conditions. In aerobic culture (K<SUB>L</SUB>a = 1.5 min<SUP>-1</SUP>), the cells expressing pdc and adhB produced 0.4g l<SUP>-1</SUP> ethanol when cultured for 18h. This value was improved in BW25113Δpta/pHfdh/pTadhB-pdc following 4g l<SUP>-1</SUP> formate feeding at 0.8g l<SUP>-1</SUP> ethanol. In higher oxygenation level (K<SUB>L</SUB>a = 6.1 min<SUP>-1</SUP>), the production of ethanol was further enhanced at 1.79g l<SUP>-1</SUP> +/- 0.37g l<SUP>-1</SUP> after 24h cultivation. Formate was found not detectable at the end of culture, indicating complete degradation this organic acid to regenerate NADH from NAD<SUP>+</SUP>. The culture strategy was effective to inactivate lactate dehydrogenase, which is major competitor for ethanol production in utilizing NADH.