TABLE 1.

Sequence diversity of selected loci among analyzed P. aeruginosa strains^a

Species	Gene locus	Mean nucleotide substitutions (%) among pairs of strains	dS	dN	GenBank accession no. of reference strain or reference
P. aeruginosa	oriC	0.40			M30125
	citS	0.25	1.18 ± 0.31	0.00	M29728
	ampC	0.38	1.11 ± 0.33	0.15 ± 0.07	X54719
	oprI	0.15	1.28 ± 0.71	0.00	X58714
	fliC	11.5
	fliC a-type	0.59	3.41 ± 0.61	0.74 ± 0.17	M57501
	fliC b-type	0.05	0.26 ± 0.19	0.00	U54775
	pilA	71.3
	pilA group I	13.3			M21652
	pilA group II	29.7			M11323
E. coli	gapA	0.2	0.78 ± 0.28	0.09 ± 0.04	33
	putP	2.4	9.04 ± 1.46	0.15 ± 0.11	31
	mdh	1.1	3.70 ± 0.65	0.15 ± 0.09	4
	gnd	7.2b			32
	icd	1.8			57
	aceK	2.9			34
Salmonella enterica	gapA	3.8	15.55 ± 1.49	0.61 ± 0.15	33
	putP	4.6	16.70 ± 1.88	0.60 ± 0.23	31
	mdh	4.5	20.13 ± 1.72	0.48 ± 0.16	4
	gnd	3.8	21.80 ± 1.40	0.44 ± 0.10	32
	icd	5.6	29.35 ± 2.00	0.25 ± 0.09	57
	aceK	5.7	28.39 ± 1.76	1.05 ± 0.14	34

^aStrain DSM 1128 is excluded because of its unusually high sequence variability in all analyzed loci. d_S and d_N indicate the average number of synonymous or nonsynonymous nucleotide substitutions using Jukes-Cantor corrections. To avoid hypervariable regions, the a-type and b-type flagellin genes were considered separately and the hypervariable pilin genes were excluded. For comparison, the following sequence variations are shown: glyceraldehyde-3-phosphate dehydrogenase gene (gapA), proline permease gene (putP), malate dehydrogenase gene (mdh), 6-phosphogluconate dehydrogenase gene (gnd), isocitrate dehydrogenase gene (icd), and isocitrate dehydrogenase kinase-phosphatase gene (aceK) in about 30 E. coli and Salmonella strains representing the major phylogenetic lineages. 

^bReflects high frequency of recombination within and among taxonomic groups because of close linkage with genes that are subject to diversifying selection (32).