Gene mobility promotes the spread of resistance in bacterial populations

Theory predicts that horizontal gene transfer (HGT) expands the selective conditions under which genes spread in bacterial populations. Whereas vertically inherited genes can only spread by positively selected clonal expansion, mobile genetic elements can drive fixation of genes by infectious HGT. W...

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Bibliographic Details
Published in:The ISME Journal 2017-08, Vol.11 (8), p.1930-1932
Main Authors: Stevenson, Cagla, Hall, James PJ, Harrison, Ellie, Wood, AJamie, Brockhurst, Michael A
Format: Article
Language:English
Subjects:
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Bacteria
Biomedical and Life Sciences
Drug Resistance, Bacterial - genetics
Ecology
Evolutionary Biology
Fixation
Gene transfer
Gene Transfer, Horizontal
Genes
Heredity
Life Sciences
Mercury
Mercury - toxicity
Microbial Ecology
Microbial Genetics and Genomics
Microbiology
Plasmids - genetics
Populations
Positive selection
Pseudomonas fluorescens
Pseudomonas fluorescens - drug effects
Pseudomonas fluorescens - genetics
Short Communication
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Summary:Theory predicts that horizontal gene transfer (HGT) expands the selective conditions under which genes spread in bacterial populations. Whereas vertically inherited genes can only spread by positively selected clonal expansion, mobile genetic elements can drive fixation of genes by infectious HGT. We tested this using populations of Pseudomonas fluorescens and the conjugative mercury resistance (Hg R ) plasmid pQBR57. HGT expanded the selective conditions allowing the spread of Hg R : Chromosomal Hg R only increased in frequency under positive selection, whereas plasmid-encoded Hg R reached fixation with or without positive selection. Tracking plasmid dynamics over time revealed that the mode of Hg R inheritance varied across mercury environments. Under mercury selection, the spread of Hg R was driven primarily by clonal expansion while in the absence of mercury Hg R dynamics were dominated by infectious transfer. Thus, HGT is most likely to drive the spread of resistance genes in environments where resistance is useless.
ISSN:1751-7362
1751-7370
DOI:10.1038/ismej.2017.42