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Related Concept Videos

Mutation, Gene Flow, and Genetic Drift01:09

Mutation, Gene Flow, and Genetic Drift

In a population that is not at Hardy-Weinberg equilibrium, the frequency of alleles changes over time. Therefore, any deviations from the five conditions of Hardy-Weinberg equilibrium can alter the genetic variation of a given population. Conditions that change the genetic variability of a population include mutations, natural selection, non-random mating, gene flow, and genetic drift (small population size).Mechanisms of Genetic VariationThe original sources of genetic variation are mutations,...
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Updated: Jul 16, 2026

Combining Magnetic Sorting of Mother Cells and Fluctuation Tests to Analyze Genome Instability During Mitotic Cell Aging in Saccharomyces cerevisiae
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phnE frameshift reversion frequency: beyond density effects to genomic prevalence.

Luísa Andrea Villanueva da Fonseca1, Marina Caldas Leite1, Beny Spira1

  • 1Departamento de Microbiologia, Instituto de Ciências Biomédicas Universidade de São Paulo, São Paulo, Brazil.

Journal of Bacteriology
|July 14, 2026
PubMed
Summary

Phosphonate utilization in E. coli is less frequent than previously thought due to phosphate contamination. Loss of phosphonate utilization genes may be an adaptive strategy in natural E. coli populations.

Keywords:
allelemutant frequencyphnEreversion

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Area of Science:

  • Microbiology
  • Molecular Biology
  • Genetics

Background:

  • Phosphonates serve as alternative phosphorus sources.
  • The phn operon in Escherichia coli mediates phosphonate uptake.
  • Previous studies reported high frequencies of phn revertants in E. coli K-12.

Purpose of the Study:

  • Reexamine phn revertant frequencies in E. coli K-12.
  • Investigate the effect of phosphate contamination and cell density on reversion.
  • Assess the fitness advantage of functional phnE under phosphate limitation.
  • Determine the prevalence of non-functional phn genes in natural E. coli isolates.

Main Methods:

  • Culturing E. coli K-12 under strictly phosphate-limited conditions.
  • Eliminating phosphate impurities from growth media.
  • Assessing revertant frequencies at varying bacterial densities.
  • Evaluating bacterial fitness with functional vs. non-functional phnE.
  • Conducting an in silico survey of phn gene functionality in E. coli genomes.

Main Results:

  • Phosphate-free conditions drastically reduced estimated revertant frequencies.
  • Bacterial density did not significantly affect revertant frequency.
  • Functional phnE provided no measurable fitness advantage under phosphate limitation.
  • Approximately 15% of natural E. coli strains lack functional phn genes.

Conclusions:

  • Reported high frequencies of phn revertants were likely artifacts of phosphate contamination.
  • Loss of phosphonate utilization does not impose a fitness cost under phosphate limitation.
  • Loss of phn gene function may be an adaptive strategy in natural E. coli populations.