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Nonselective bottlenecks control the divergence and diversification of phase-variable bacterial populations

Aidley, Jack B.; Rajopadhye, Shweta; Akinyemi, Nwanekka; Lango-Scholey, Lea; Jones, Michael A.; Bayliss, Christopher D.

Authors

Jack B. Aidley jba9@leicester.ac.uk

Shweta Rajopadhye

Nwanekka Akinyemi

Lea Lango-Scholey

Michael A. Jones michael.a.jones@nottingham.ac.uk

Christopher D. Bayliss cdb12@leicester.ac.uk



Abstract

Phase variation occurs in many pathogenic and commensal bacteria and is a major generator of genetic variability. A putative advantage of phase variation is to counter reductions in variability imposed by nonselective bottlenecks during transmission. Genomes of Campylobacter jejuni, a widespread food-borne pathogen, contain multiple phase-variable loci whose rapid, stochastic variation is generated by hypermutable simple sequence repeat tracts. These loci can occupy a vast number of combinatorial expression states (phasotypes) enabling populations to rapidly access phenotypic diversity. The imposition of nonselective bottlenecks can perturb the relative frequencies of phasotypes, changing both within-population diversity and divergence from the initial population. Using both in vitro testing of C. jejuni populations and a simple stochastic simulation of phasotype change, we observed that single-cell bottlenecks produce output populations of low diversity but with bimodal patterns of either high or low divergence. Conversely, large bottlenecks allow divergence only by accumulation of diversity, while interpolation between these extremes is observed in intermediary bottlenecks. These patterns are sensitive to the genetic diversity of initial populations but stable over a range of mutation rates and number of loci. The qualitative similarities of experimental and in silico modeling indicate that the observed patterns are robust and applicable to other systems where localized hypermutation is a defining feature. We conclude that while phase variation will maintain bacterial population diversity in the face of intermediate bottlenecks, narrow transmission-associated bottlenecks could produce host-to-host variation in bacterial phenotypes and hence stochastic variation in colonization and disease outcomes.

Journal Article Type Article
Publication Date Apr 4, 2017
Journal mBio
Electronic ISSN 2150-7511
Publisher American Society for Microbiology
Peer Reviewed Peer Reviewed
Volume 8
Issue 2
APA6 Citation Aidley, J. B., Rajopadhye, S., Akinyemi, N., Lango-Scholey, L., Jones, M. A., & Bayliss, C. D. (2017). Nonselective bottlenecks control the divergence and diversification of phase-variable bacterial populations. mBio, 8(2), https://doi.org/10.1128/mBio.02311-16
DOI https://doi.org/10.1128/mBio.02311-16
Keywords Campylobacter
Phase-variation
Publisher URL http://mbio.asm.org/content/8/2/e02311-16
Related Public URLs https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5550753/pdf/mBio.00878-17.pdf
Copyright Statement Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by/4.0
Additional Information Authorship error lead to omission this is corrected in amendment attached as separate pdf.

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Copyright Statement
Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by/4.0


mBio.00878-17.pdf (107 Kb)
PDF

Copyright Statement
Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by/4.0





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