Stochastic receptor expression allows sensitive bacteria to evade phage attack. Part I: experiments.
It has long been suspected that population heterogeneity, either at a genetic level or at a protein level, can improve the fitness of an organism under a variety of environmental stresses. However, quantitative measurements to substantiate such a hypothesis turn out to be rather difficult and have rarely been performed. Herein, we examine the effect of expression heterogeneity of lambda-phage receptors on the response of an Escherichia coli population to attack by a high concentration of lambda-phage. The distribution of the phage receptors in the population was characterized by flow cytometry, and the same bacterial population was then subjected to different phage pressures. We show that a minority population of bacteria that produces the receptor slowly and at low levels determines the long-term survivability of the bacterial population and that phage-resistant mutants can be efficiently isolated only when the persistent phage pressure >10(10) viruses/cm(3) is present. Below this phage pressure, persistors instead of mutants are dominant in the population.
Chapman-McQuiston
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Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
Wu
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D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism*; D010582:Bacteriophage lambda / Q000502:physiology*; D003198:Computer Simulation; D004926:Escherichia coli / Q000502:physiology* / Q000821:virology*; D008954:Models, Biological; D015233:Models, Statistical; D018272:Porins / Q000378:metabolism*; D011991:Receptors, Virus / Q000378:metabolism*; D013269:Stochastic Processes
D001425:Bacterial Outer Membrane Proteins; D018272:Porins; D011991:Receptors, Virus; C016532:maltoporins