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Evolution of Diversity in Spatially Structured Escherichia coli Populations

Evolution of Diversity in Spatially Structured Escherichia coli Populations Evolution of Diversity in Spatially Structured Escherichia coli Populations ▿ José Miguel Ponciano 1 , 2 , 4 , † , Hyun-Joon La 3 , Paul Joyce 1 , 2 , 4 and Larry J. Forney 3 , 4 , * 1 Departments of Mathematics 2 Statistics 3 Biological Sciences 4 the Initiative for Bioinformatics and Evolutionary Studies (IBEST), University of Idaho, Moscow, Idaho 83844-3051 ABSTRACT The stochastic Ricker population model was used to investigate the generation and maintenance of genetic diversity in a bacterial population grown in a spatially structured environment. In particular, we showed that Escherichia coli undergoes dramatic genetic diversification when grown as a biofilm. Using a novel biofilm entrapment method, we retrieved 64 clones from each of six different depths of a mature biofilm, and after subculturing for ∼30 generations, we measured their growth kinetics in three different media. We fit a stochastic Ricker population growth model to the recorded growth curves. The growth kinetics of clonal lineages descendant from cells sampled at different biofilm depths varied as a function of both the depth in the biofilm and the growth medium used. We concluded that differences in the growth dynamics of clones were heritable and arose during adaptive evolution under local conditions in a spatially heterogeneous environment. We postulate that under nutrient-limited conditions, selective sweeps would be protracted and would be insufficient to purge less-fit variants, a phenomenon that would allow the coexistence of genetically distinct clones. These findings contribute to the current understanding of biofilm ecology and complement current hypotheses for the maintenance and generation of microbial diversity in spatially structured environments. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Applied and Environmental Microbiology American Society For Microbiology

Evolution of Diversity in Spatially Structured Escherichia coli Populations

Evolution of Diversity in Spatially Structured Escherichia coli Populations

Applied and Environmental Microbiology , Volume 75 (19): 6047 – Oct 1, 2009

Abstract

Evolution of Diversity in Spatially Structured Escherichia coli Populations ▿ José Miguel Ponciano 1 , 2 , 4 , † , Hyun-Joon La 3 , Paul Joyce 1 , 2 , 4 and Larry J. Forney 3 , 4 , * 1 Departments of Mathematics 2 Statistics 3 Biological Sciences 4 the Initiative for Bioinformatics and Evolutionary Studies (IBEST), University of Idaho, Moscow, Idaho 83844-3051 ABSTRACT The stochastic Ricker population model was used to investigate the generation and maintenance of genetic diversity in a bacterial population grown in a spatially structured environment. In particular, we showed that Escherichia coli undergoes dramatic genetic diversification when grown as a biofilm. Using a novel biofilm entrapment method, we retrieved 64 clones from each of six different depths of a mature biofilm, and after subculturing for ∼30 generations, we measured their growth kinetics in three different media. We fit a stochastic Ricker population growth model to the recorded growth curves. The growth kinetics of clonal lineages descendant from cells sampled at different biofilm depths varied as a function of both the depth in the biofilm and the growth medium used. We concluded that differences in the growth dynamics of clones were heritable and arose during adaptive evolution under local conditions in a spatially heterogeneous environment. We postulate that under nutrient-limited conditions, selective sweeps would be protracted and would be insufficient to purge less-fit variants, a phenomenon that would allow the coexistence of genetically distinct clones. These findings contribute to the current understanding of biofilm ecology and complement current hypotheses for the maintenance and generation of microbial diversity in spatially structured environments.

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Publisher
American Society For Microbiology
Copyright
Copyright © 2009 by the American society for Microbiology.
ISSN
0099-2240
eISSN
1098-5336
DOI
10.1128/AEM.00063-09
pmid
19648364
Publisher site
See Article on Publisher Site

Abstract

Evolution of Diversity in Spatially Structured Escherichia coli Populations ▿ José Miguel Ponciano 1 , 2 , 4 , † , Hyun-Joon La 3 , Paul Joyce 1 , 2 , 4 and Larry J. Forney 3 , 4 , * 1 Departments of Mathematics 2 Statistics 3 Biological Sciences 4 the Initiative for Bioinformatics and Evolutionary Studies (IBEST), University of Idaho, Moscow, Idaho 83844-3051 ABSTRACT The stochastic Ricker population model was used to investigate the generation and maintenance of genetic diversity in a bacterial population grown in a spatially structured environment. In particular, we showed that Escherichia coli undergoes dramatic genetic diversification when grown as a biofilm. Using a novel biofilm entrapment method, we retrieved 64 clones from each of six different depths of a mature biofilm, and after subculturing for ∼30 generations, we measured their growth kinetics in three different media. We fit a stochastic Ricker population growth model to the recorded growth curves. The growth kinetics of clonal lineages descendant from cells sampled at different biofilm depths varied as a function of both the depth in the biofilm and the growth medium used. We concluded that differences in the growth dynamics of clones were heritable and arose during adaptive evolution under local conditions in a spatially heterogeneous environment. We postulate that under nutrient-limited conditions, selective sweeps would be protracted and would be insufficient to purge less-fit variants, a phenomenon that would allow the coexistence of genetically distinct clones. These findings contribute to the current understanding of biofilm ecology and complement current hypotheses for the maintenance and generation of microbial diversity in spatially structured environments.

Journal

Applied and Environmental MicrobiologyAmerican Society For Microbiology

Published: Oct 1, 2009

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