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The putative influence of the agr operon upon survival mechanisms used by Clostridium acetobutylicum

Jabbari, Sara; Steiner, Elisabeth; Heap, John T.; Winzer, Klaus; Minton, Nigel P.; King, John R.


Sara Jabbari

Elisabeth Steiner

John T. Heap

Professor of Appliedmolecular Microbiology

Professor of Theoretical Mechanics


The bacterium Clostridium acetobutylicum produces acids as an energy-yielding process during exponential growth. An acidic environment, however, is toxic to the cells and two survival mechanisms are in place to prevent them from dying. Firstly, during a solventogenesis phase, the cells
take up these acids and convert them to solvents, thus raising the environmental pH. Secondly, the cells undergo sporulation to form highly resistant spores capable of surviving extreme conditions. One possible regulatory mechanism for these processes is the accessory gene regulatory (agr) quorum-sensing system, which is thought to coordinate cell population density with cell phenotype. We model this system to monitor its putative e.ect upon solventogenesis and the sporulation-initiation network responsible for triggering spore formation. We demonstrate that a high population density should be able to induce both solventogenesis and sporulation, with variations to the parameter set allowing sporulation alone to be triggered; additional distinct signals are capable of restoring the solventogenic response. We compare the agr system of C. acetobutylicum with that of Staphylococcus aureus in order to investigate why the di.erences in feedback between the two systems may have evolved. Our findings indicate that, depending upon the mechanism of interaction between the agr system and the sporulation-initiation network, the clostridial agr circuitry may be in place either to moderate the number of spores that are formed (in order for this number to reflect the urgency of the situation), or simply as an energy-saving strategy.


Jabbari, S., Steiner, E., Heap, J. T., Winzer, K., Minton, N. P., & King, J. R. (2013). The putative influence of the agr operon upon survival mechanisms used by Clostridium acetobutylicum. Mathematical Biosciences, 243(2), doi:10.1016/j.mbs.2013.03.005

Journal Article Type Article
Publication Date Mar 26, 2013
Deposit Date Nov 20, 2013
Publicly Available Date Nov 20, 2013
Journal Mathematical Biosciences
Print ISSN 0025-5564
Electronic ISSN 0025-5564
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 243
Issue 2
Public URL
Publisher URL
Additional Information NOTICE: this is the author’s version of a work that was accepted for publication in Mathematical Biosciences. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Mathematical Biosciences, 243(2), 2013. doi: 10.1016/j.mbs.2013.03.005 PMID-23538287


PMID-23538287.pdf (449 Kb)

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