TABLE 2 .

Selection of growth-compensatory mutations in srrAB^a

Parental strain (and evolved strain[s])	SCV mutation	srrAB mutation	Mean fitness ± SD	Kan MIC
AH704	menA E72K		0.28 ± 0.01	64
AH631	menB G81*		0.25 ± 0.01	64
AH846	menB D98G		0.27 ± 0.02	48
AH1560	menB D98G	srrB T373K	0.53 ± 0.02	48
AH841	menB G121D		0.29 ± 0.01	64
AH1576	menB G121D	srrB T373K	0.38 ± 0.00	48
AH635	menE Y31*		0.28 ± 0.02	32
AH1570	menE Y31*	srrA M55I	0.41 ± 0.01	32
AH839	hemE A211fs		0.36 ± 0.01	48
AH1643	hemE A211fs	srrB A250T	0.57 ± 0.01	48
AH1647	hemE A211fs	srrB A487T	056 ± 0.00	48

^aGrowth-compensatory mutations were selected by serial passage of 5 lineages of each of 6 SCV parental strains for 150 generations in LB supplemented with 15 mg/liter kanamycin. Growth compensation occurred in 7 lineages. Mutations in srrA or srrB were identified in 5 of these lineages. (Genotypes and phenotypes of the evolved strains are shown in boldface.) All growth-compensated mutants grow significantly faster than the respective parental strains (t test, P < 0.001).