Table 1. The data of essential genes used in the current study.

Organism	RefSeq	No. of total genes	No. of essential genes	References
Acinetobacter sp. ADP1	NC_005966	3307	499	[26]
Bacillus subtilis subsp. subtilis str. 168	NC_000964	4176	271	[10]
Escherichia coli K12	NC_000913	4144	700a	[27], [28]
Francisella tularensis subsp. novicida U112	NC_008601	1719	390	[35]
Haemophilus influenzae Rd KW20	NC_000907	1657	462	[32]
Helicobacter pylori 26695	NC_000915	1573	322b	[36]
Mycobacterium tuberculosis H37Rv	NC_000962	3988	614	[37]
Mycoplasma genitalium G37	NC_000908	475	378c	[38]
Mycoplasma pulmonis UAB CTIP	NC_002771	782	310	[39]
Pseudomonas aeruginosa UCBPP-PA14	NC_008463	5892	335	[40]
Salmonella enterica subsp. enterica serovar Typhi Ty2	NC_004631	4314	353	[41]
Salmonella typhimurium LT2	NC_003197	4423	230	[42]
Staphylococcus aureus subsp. aureus N315	NC_002745	2583	302	[29], [30], [31]
Staphylococcus aureus subsp. aureus NCTC 8325	NC_007795	2892	351	[43]

^aNote that for the genome of NC_000913, ten essential genes without GI numbers and two essential genes with dead GI numbers (16129191 and 16130842) were excluded.

^bNote that for the genome of NC_000915, one essential gene with dead GI number (15644641) was excluded.

^cNote that for the genome of NC_000908, two essential genes without GI numbers and one essential gene with dead GI number (13277519) were excluded.