earticle

영어

A typical butanol producing clostridium such as Clostridium acetobutylicum ATCC 824 rarely yields higher than 13 g/L of butanol in the batch culture due to solvent toxicity, feedback inhibition, etc. In this study, the pfkA (6- phosphofructokinase) and pykA (pyruvate kinase) genes of C. acetobutylicum ATCC 824 were over-expressed in the same strain in order to enhance the butanol production possibly by lowering the inhibitory effect of the solvent. These genes were PCR-amplified from the genomic DNA of C. acetobutylicum ATCC 824 and inserted into the pSOS94 plasmid under the control of phosphate butyryltransferase promoter. The recombinant plasmids (pSO94/pfkA, pSO94/pykA, and pSO94/ pfkA+pykA) were then electroporated back into C. acetobutylicum ATCC 824. In a 5 liter fed-batch bioreactor, butanol and ethanol concentrations of ATCC 824/ pSO94/pfkA+pykA reached 19.03 g/L and 2.93 g/L, respectively, which were 32.7% and 1.08% higher than those from the wild type C. acetobutylicum ATCC 824. The total solvent concentration also increased by 25.7%. Interestingly, the acetone concentration of ATCC824/pSO94/pfkA+pykA was lower by 12.1% than that of the wild type. The intracellular NADH and ATP concentrations in the solventogenesis of the strain ATCC 824/pSO94/pfkA+pykA were also higher than the wild type C. acetobutylicum ATCC 824, which were thought to improve butanol production and tolerance of the recombinant strain to solvent toxicity.