title: Directed assembly of a bacterial quorum.
abstract: Many reports have elucidated the mechanisms and consequences of bacterial quorum sensing (QS), a molecular communication system by which bacterial cells enumerate their cell density and organize collective behavior. In few cases, however, the numbers of bacteria exhibiting this collective behavior have been reported, either as a number concentration or a fraction of the whole. Not all cells in the population, for example, take on the collective phenotype. Thus, the specific attribution of the postulated benefit can remain obscure. This is partly due to our inability to independently assemble a defined quorum, for natural and most artificial systems the quorum itself is a consequence of the biological context (niche and signaling mechanisms). Here, we describe the intentional assembly of quantized quorums. These are made possible by independently engineering the autoinducer signal transduction cascade of Escherichia coli (E. coli) and the sensitivity of detector cells so that upon encountering a particular autoinducer level, a discretized sub-population of cells emerges with the desired phenotype. In our case, the emergent cells all express an equivalent amount of marker protein, DsRed, as an indicator of a specific QS-mediated activity. The process is robust, as detector cells are engineered to target both large and small quorums. The process takes about 6 h, irrespective of quorum level. We demonstrate sensitive detection of autoinducer-2 (AI-2) as an application stemming from quantized quorums. We then demonstrate sub-population partitioning in that AI-2-secreting cells can 'call' groups neighboring cells that 'travel' and establish a QS-mediated phenotype upon reaching the new locale.
authors.affiliation: US Army Research Laboratory, Sensors and Electron Devices Directorate, Adelphi, MD, USA.
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Servinsky
authors.affiliation: Fischell Department of Bioengineering, University of Maryland, College Park, MD, USA.|Institute for Bioscience and Biotechnology Research, University of Maryland, College Park, MD, USA.
authors.forename: Jessica L
authors.initials: JL
authors.lastname: Terrell
authors.affiliation: Fischell Department of Bioengineering, University of Maryland, College Park, MD, USA.|Institute for Bioscience and Biotechnology Research, University of Maryland, College Park, MD, USA.
authors.forename: Chen-Yu
authors.initials: CY
authors.lastname: Tsao
authors.affiliation: Fischell Department of Bioengineering, University of Maryland, College Park, MD, USA.|Institute for Bioscience and Biotechnology Research, University of Maryland, College Park, MD, USA.
authors.forename: Hsuan-Chen
authors.initials: HC
authors.lastname: Wu
authors.affiliation: Fischell Department of Bioengineering, University of Maryland, College Park, MD, USA.|Institute for Bioscience and Biotechnology Research, University of Maryland, College Park, MD, USA.
authors.forename: David N
authors.initials: DN
authors.lastname: Quan
authors.affiliation: Fischell Department of Bioengineering, University of Maryland, College Park, MD, USA.|Institute for Bioscience and Biotechnology Research, University of Maryland, College Park, MD, USA.
authors.forename: Amin
authors.initials: A
authors.lastname: Zargar
authors.affiliation: US Army Research Laboratory, Sensors and Electron Devices Directorate, Adelphi, MD, USA.
authors.forename: Patrick C
authors.initials: PC
authors.lastname: Allen
authors.affiliation: US Army Research Laboratory, Sensors and Electron Devices Directorate, Adelphi, MD, USA.|Fischell Department of Bioengineering, University of Maryland, College Park, MD, USA.|Institute for Bioscience and Biotechnology Research, University of Maryland, College Park, MD, USA.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Byrd
authors.affiliation: US Army Research Laboratory, Sensors and Electron Devices Directorate, Adelphi, MD, USA.
authors.forename: Christian J
authors.initials: CJ
authors.lastname: Sund
authors.affiliation: Fischell Department of Bioengineering, University of Maryland, College Park, MD, USA.|Institute for Bioscience and Biotechnology Research, University of Maryland, College Park, MD, USA.
authors.forename: William E
authors.initials: WE
authors.lastname: Bentley
mesh_terms: D004926:Escherichia coli / Q000235:genetics / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D006714:Homoserine / Q000031:analogs & derivatives / Q000378:metabolism; D007783:Lactones / Q000378:metabolism; D053038:Quorum Sensing; D015398:Signal Transduction
chemical_list: D029968:Escherichia coli Proteins; D007783:Lactones; C091088:N-octanoylhomoserine lactone; D006714:Homoserine