Chance and pleiotropy dominate genetic diversity in complex bacterial environments

Lianet Noda-García, Dan Davidi, Elisa Korenblum, Assaf Elazar, Ekaterina Putintseva, Asaph Aharoni, Dan S. Tawfik*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


How does environmental complexity affect the evolution of single genes? Here, we measured the effects of a set of Bacillus subtilis glutamate dehydrogenase mutants across 19 different environments—from phenotypically homogeneous single-cell populations in liquid media to heterogeneous biofilms, plant roots and soil populations. The effects of individual gene mutations on organismal fitness were highly reproducible in liquid cultures. However, 84% of the tested alleles showed opposing fitness effects under different growth conditions (sign environmental pleiotropy). In colony biofilms and soil samples, different alleles dominated in parallel replica experiments. Accordingly, we found that in these heterogeneous cell populations the fate of mutations was dictated by a combination of selection and drift. The latter relates to programmed prophage excisions that occurred during biofilm development. Overall, for each condition, a wide range of glutamate dehydrogenase mutations persisted and sometimes fixated as a result of the combined action of selection, pleiotropy and chance. However, over longer periods and in multiple environments, nearly all of this diversity would be lost—across all the environments and conditions that we tested, the wild type was the fittest allele.

Original languageAmerican English
Pages (from-to)1221-1230
Number of pages10
JournalNature Microbiology
Issue number7
StatePublished - 1 Jul 2019
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2019, The Author(s), under exclusive licence to Springer Nature Limited.


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