Improvement of butanol production in Clostridium acetobutylicum through enhancement of NAD(P)H availability
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Clostridium acetobutylicum is a natural producer of butanol, butyrate, acetone and ethanol. The pattern of metabolites reflects the partitioning of redox equivalents between hydrogen and carbon metabolites. Here the exogenous genes of ferredoxin-NAD(P)+ oxidoreductase (FdNR) and trans-enoyl-coenzyme reductase (TER) are introduced to three different Clostridium acetobutylicum strains to investigate the distribution of redox equivalents and butanol productivity. The FdNR improves NAD(P)H availability by capturing reducing power from ferredoxin. A butanol production of 9.01 g/L (36.9% higher than the control), and the highest ratios of butanol/acetate (7.02) and C4/C2 (3.17) derived metabolites were obtained in the C acetobutylicum buk- strain expressing FdNR. While the TER functions as an NAD(P)H oxidase, butanol production was decreased in the C. acetobutylicum strains containing TER. The results illustrate that metabolic flux can be significantly changed and directed into butanol or butyrate due to enhancement of NAD(P)H availability by controlling electron flow through the ferredoxin node.
KeywordsClostridium acetobutylicum NAD(P)H Redox FdNR Ferredoxin TER
The work was supported by Department of Energy Grant DE-SC0014462 and Natural Science Foundation of Fujian Province of China (No. 2016J01148; 2016J01147). Some preliminary experiments were supported by Army Research Office, grant number W911NF0910119.
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All the authors declare that he/she has no conflict of interest.
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