초록
<P>Promising approaches to produce higher alcohols, e.g., isobutanol, using <I>Escherichia coli</I> have been developed with successful results. Here, we translated the isobutanol process from shake flasks to a 1-L bioreactor in order to characterize three <I>E. coli</I> strains. With in situ isobutanol removal from the bioreactor using gas stripping, the engineered <I>E. coli</I> strain (JCL260) produced more than 50 g/L in 72 h. In addition, the isobutanol production by the parental strain (JCL16) and the high isobutanol-tolerant mutant (SA481) were compared with JCL260. Interestingly, we found that the isobutanol-tolerant strain in fact produced worse than either JCL16 or JCL260. This result suggests that in situ product removal can properly overcome isobutanol toxicity in <I>E. coli</I> cultures. The isobutanol productivity was approximately twofold and the titer was 9% higher than <I>n</I>-butanol produced by <I>Clostridium</I> in a similar integrated system.</P>