Recombination resolves the cost of horizontal gene transfer in experimental populations of Helicobacter pylori

An N.T. Nguyen, Laura C. Woods, Rebecca Gorrell, Shamitraa Ramanan, Terry Kwok, Michael J. McDonald

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6 Citations (Scopus)


Horizontal gene transfer (HGT) is important for microbial evolution, yet we know little about the fitness effects and dynamics of horizontally transferred genetic variants. In this study, we evolve laboratory populations of Helicobacter pylori, which take up DNA from their environment by natural transformation, and measure the fitness effects of thousands of transferred genetic variants. We find that natural transformation increases the rate of adaptation but comes at the cost of significant genetic load. We show that this cost is circumvented by recombination, which increases the efficiency of selection by decoupling deleterious and beneficial genetic variants. Our results show that adaptation with HGT, pervasive in natural microbial populations, is shaped by a combination of selection, recombination, and genetic drift not accounted for in existing models of evolution.

Original languageEnglish
Article numbere2119010119
Number of pages10
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number12
Publication statusPublished - 22 Mar 2022


  • Antibiotic resistance
  • Evolution
  • Experimental evolution
  • H. pylori
  • Horizontal gene transfer

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