Whole-genome resequencing of Escherichia coli K-12 MG1655 undergoing short-term laboratory evolution in lactate minimal media reveals flexible selection of adaptive mutations

Table 2 Growth rate recovery of site-directed mutants

Strain	Mutations	Growth rate (± SD)	Known mutations present	Recovery
Wild type		0.23 ± 0.02	-	-
LactA	crp	0.29 ± 0.02	1/3	26%
	Endpoint	0.47 ± 0.03	-	-
LactC	rph	0.27 ± 0.002	1/3	17%
	cya	0.26 ± 0.03	1/3	13%
	infC	0.26 ± 0.003	1/3	12%
	cya + infC	0.31 ± 0.01	2/3	39%
	cya + infC + rph	0.40 ± 0.02	3/3	82%
	Endpoint	0.44 ± 0.01	-	-
LactD	kdtA	No growth	1/7	No growth
	atoS	0.24 ± 0.01	1/7	2%
	ppsA	0.23 ± 0.01	1/7	1%
	relA	0.28 ± 0.01	1/7	19%
	rho	0.25 ± 0.003	1/7	9%
	relA + ppsA	0.33 ± 0.01	2/7	38%
	kdtA + ppsA	0.27 ± 0.02	2/7	15%
	kdtA + ppsA + atoS	0.28 ± 0.01	3/7	21%
	kdtA + ppsA + atoS + rhoO	0.34 ± 0.03	4/7	42%
	kdtA + ppsA + atoS + rho + relA	0.39 ± 0.01	5/7	64%
	Endpoint	0.48 ± 0.05	-	-
LactE	yjbM	0.23 ± 0.02	1/7	1%
	ppsA	0.25 ± 0.02	1/7	10%
	crp	0.27 ± 0.02	1/7	17%
	ppsA + crp	0.28 ± 0.03	2/7	24%
	ppsA + crp + yjbM	0.31 ± 0.04	3/7	37%
	Endpoint	0.43 ± 0.02	-	-

To determine the causality of the observed mutations, site-directed mutagenesis was used to place mutations individually and in combination into a wild-type (MG1655) background. Average growth rate measurements of strains grown at 30°C in lactate M9 minimal media are shown. Growth rate recovery is defined as the difference in growth rate between the mutant and wild type, divided by the difference in growth rate between the respective endpoint strain and wild type. The kdtA single mutant was unable to grow without amino acid supplementation.

ISSN: 1474-760X