This Article Full Text Full Text (PDF) Supplemental material Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Portnoy, V. A. Articles by Palsson, B. O. Search for Related Content PubMed PubMed Citation Articles by Portnoy, V. A. Articles by Palsson, B. O. Agricola Articles by Portnoy, V. A. Articles by Palsson, B. O.

 Previous Article  |  Next Article 

Applied and Environmental Microbiology, December 2008, p. 7561-7569, Vol. 74, No. 24
0099-2240/08/$08.00+0     doi:10.1128/AEM.00880-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Aerobic Fermentation of D-Glucose by an Evolved Cytochrome Oxidase-Deficient Escherichia coli Strain ^,

Vasiliy A. Portnoy, Markus J. Herrgård,^# and Bernhard Ø. Palsson^*

Department of Bioengineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0412

Received 17 April 2008/ Accepted 17 October 2008

Fermentation of glucose to D-lactic acid under aerobic growth conditions by an evolved Escherichia coli mutant deficient in three terminal oxidases is reported in this work. Cytochrome oxidases (cydAB, cyoABCD, and cbdAB) were removed from the E. coli K12 MG1655 genome, resulting in the ECOM3 (E. coli cytochrome oxidase mutant) strain. Removal of cytochrome oxidases reduced the oxygen uptake rate of the knockout strain by nearly 85%. Moreover, the knockout strain was initially incapable of growing on M9 minimal medium. After the ECOM3 strain was subjected to adaptive evolution on glucose M9 medium for 60 days, a growth rate equivalent to that of anaerobic wild-type E. coli was achieved. Our findings demonstrate that three independently adaptively evolved ECOM3 populations acquired different phenotypes: one produced lactate as a sole fermentation product, while the other two strains exhibited a mixed-acid fermentation under oxic growth conditions with lactate remaining as the major product. The homofermenting strain showed a D-lactate yield of 0.8 g/g from glucose. Gene expression and in silico model-based analyses were employed to identify perturbed pathways and explain phenotypic behavior. Significant upregulation of ygiN and sodAB explains the remaining oxygen uptake that was observed in evolved ECOM3 strains. E. coli strains produced in this study showed the ability to produce lactate as a fermentation product from glucose and to undergo mixed-acid fermentation during aerobic growth.

---

* Corresponding author. Mailing address: Department of Bioengineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0412. Phone: (858) 534-3668. Fax: (858) 822-3120. E-mail: bpalsson{at}bioeng.ucsd.edu

Published ahead of print on 24 October 2008.

Supplemental material for this article may be found at http://aem.asm.org/.

^# Present address: Synthetic Genomics, Inc., 11149 N. Torrey Pines Rd., La Jolla, CA 92037.

---

Applied and Environmental Microbiology, December 2008, p. 7561-7569, Vol. 74, No. 24
0099-2240/08/$08.00+0     doi:10.1128/AEM.00880-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

This article has been cited by other articles:

• Bekker, M., de Vries, S., Ter Beek, A., Hellingwerf, K. J., de Mattos, M. J. T. (2009). Respiration of Escherichia coli Can Be Fully Uncoupled via the Nonelectrogenic Terminal Cytochrome bd-II Oxidase. J. Bacteriol. 191: 5510-5517 [Abstract] [Full Text]