Stable polyphosphate accumulation by a pseudo-revertant of an Escherichia coli phoU mutant
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phoU mutants of bacteria are potentially useful for the removal of inorganic phosphate (Pi) from sewage because they can accumulate a large amounts of polyphosphate (polyP). However, the growth of phoU mutants is severely defective and is easily outgrown by revertant(s) that have lost the ability to accumulate polyP during growth in a nutrient-rich medium. We found that a pseudo-revertant, designated LAP[+], that appeared in a culture of an Escherichia coli phoU mutant that could accumulate polyP even after ten serial passages. Reduction in the expression of the Pi-specific transporter Pst in LAP[+] may contribute to relieving stresses such as excess Pi incorporation that could stimulate reversions. The discovery of a LAP[+] provides a clue to generate phoU mutants that accumulate polyP in a stable manner.
KeywordsEscherichia coli Mutation Phosphate removal PhoU Polyphosphate
This work was supported by Grant-in-Aid for Young Scientists (B) from the Japan Society for the Promotion of Science (KAKENHI, number 21780075 and 23780083). We are grateful to the National Bioresource Project (National Institute of Genetics, Japan) for E. coli strains. We thank M. Alexandrov for critical discussion and for reading the manuscript.
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