TABLE 4.

Uncoupling mutations obtained by localized mutagenesis^a

Mutation	Plasmid	LGS322			LGS322/F′DalD
		Doubling time (min) on Mtl	Growth yield (OD600) on Mtl	Growth on Atl	Doubling time (min) on Mtl	Growth yield (OD600) on Mtl	Growth on Atl
None (wild-type E. coli)	pGJ9Δ137	NG	NG	s	NG	NG	2+
	pGJ9	85	8.0	s	85	7.7	2+
None (wild-type K. pneumoniae)	pSOL110	NG	NG	s	NG	NG	2+
	pSOL300	100	6.7	s	100	6.5	2+
E218A	pGJΔ137	NG	NG	s	200	3.5	2+
	pGJ9	190	4.2	s	117	7.0	2+
E218V	pGJ9Δ137	NG	NG	s	190	4.0	2+
	pGJ9	300	2.7	s	110	6.8	2+
H256P	pGJ9Δ137	NG	NG	s	≤300	2.5	2+
	pGJ9	NG	NG	s	280	3.9	2+
H267Y	pSOL114	NG	NG	s	250	2.5	2+
	pSOL314	105	7.0	s	85	6.9	2+

^aThe mutations were generated by localized mutagenesis in the complete or truncated mtlA gene of E. coli K-12 by exchanging 2 bp in the corresponding triplets to minimize reversions. The H256Y allele was obtained by selection in the mtlA gene of K. pneumoniae and was also present in the complete form (pSOL300) and in the deleted form (pSOL110). Cells of strains LGS322 and LGS322/F′DalD transformed with the plasmids were tested for growth in minimal d-mannitol (0.2%) medium (Mtl) and on MacConkey indicator plates containing d-arabinitol (Atl). s, sensitive; 2+, purple or deep purple colonies; OD₆₀₀, optical density at 600 nm; NG, no growth.