Organism Total genes Methodology References
Escherichia Coli 4279 Transposon mutagenesis Gerdes et al., [25]
Bacillus Subtilis 4101 Plasmidinsertionmutagenesis.Conditional mutants. Estimations derivedfrom literature study. Kobayashi et al., [29]
Haemophilus Influenza 1709 Transposon mutagenesis Akerley et al., [28]
Helicobacter Pylori 1552 Transposon mutagenesis Salama et al., [26]
Mycoplasma Genitalium 484 Transposon mutagenesis Hutchison et al., [23]
Staphylococcus Aureus 2595 Antisense RNA expression Jiang et al., [33]
Staphylococcus Pneumonia 2043 Plasmid insertion mutagenesis Thanassi et al., [30]
Table 1: Number of potential essential genes identified in genome-wide gene inactivation studies.