An estimation of minimal genome size required for life

Mitsuhiro Itaya

Research output: Contribution to journalArticlepeer-review

136 Citations (Scopus)


The number of indispensable chromosomal loci for a bacterium, Bacillus subtilis was estimated. Seventy-nine randomly selected chromosomal loci were investigated by mutagenesis. Mutation at only six loci rendered B. subtilis unable to form colonies. In contrast, mutants for the rest of the 73 loci retained the ability to form colonies. Mutant B. subtilis with multiple-fold mutations of those dispensable loci (7-, 12- or 33-fold) were not impaired in their ability to form colonies on nutritionally adequate medium, indicating that up to 33 dispensable loci were simultaneously abolished. Given the statistical analyses for the frequency of indispensable loci (6 out of 79), total indispensable genetic material would be included within about 562 kbp. The hypothetical minimum genome size lies in the range of those currently determined smallest genomes for bacteria.

Original languageEnglish
Pages (from-to)257-260
Number of pages4
JournalFEBS Letters
Issue number3
Publication statusPublished - 1995 Apr 10
Externally publishedYes


  • Colony formation
  • Dispensable gene
  • Indispensable gene
  • Minimal genome
  • Mutagenesis
  • Nutrition

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology
  • Genetics
  • Cell Biology


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