926. Cost-effective regulation of exoproducts through quorum sensing
Session: Poster Abstract Session: Bacterial Pathogenesis
Saturday, October 22, 2011
Room: Poster Hall B1
Background: Many bacteria secrete exoproducts to alleviate stress resulting from competition, starvation and host infection. The production of these exoproducts is often controlled by quorum sensing (QS), a mechanism by which bacteria sense and respond to changes in their density. It has been speculated that QS is an optimal regulatory strategy: it can delay production of costly exoproducts until a sufficiently high cell density, when the overall benefit of the exoproducts outweighs cost of their production. While it appears intuitive, however, this notion has not been experimentally established.

Methods: We engineered synthetic gene circuits in Escherichia coli to control the expression of a costly but beneficial exoenzyme. 

Results: Using these circuits, we show that exoenzyme production is overall beneficial only when initiated at a sufficiently high density. This property demonstrates the potential advantage for QS based regulation when the initial bacterial density is sufficiently low and the growth period is sufficiently long. 

Conclusion: We show that an optimally tuned QS module provides a robust control mechanism to ensure overall beneficial production of a costly exoproduct. Our results, when combined with mechanisms such as kin selection that maintain cooperation in heterogeneous populations, could explain the pervasiveness of QS regulation in bacteria. QS has been the focus of recent investigations where disrupting signaling is being examined as a novel alternative therapy against pathogens over traditional antibiotics. By elucidating the underlying advantage of QS-control, our study could help guide and predict the effects of therapies that disrupt or modulate QS.

Subject Category: B. Bacterial pathogenesis, studies in animal models, molecular pathogenicity

Anand Pai1,2, Yu Tanouchi1,3 and Lingchong You4, (1)Dept. Biomedical Engineering, Duke University, Durham, NC, (2) Institute for Genome Sciences and Policy, Duke University, Durham, NC, (3)Institute for Genome Sciences and Policy, Duke University, Durham, NC, (4)Biomedical Engineering, Institute for Genome Sciences and Policy, Center for Systems Biology, Duke University , Durham, NC


A. Pai, None

Y. Tanouchi, None

L. You, None

Findings in the abstracts are embargoed until 12:01 a.m. EST Thursday, Oct. 20 with the exception of research findings presented at IDSA press conferences.