TABLE 3.

Effects of gene deletions on succinate production

Strain	Genetic modification(s)	Time (days)	Cell mass (g liter−1)	Fermentation product concn (mM)b
				Mal	Suc	Pyr	Ace	For
KJ060a	ATCC 8739 ΔldhA ΔackA ΔadhE ΔpflB	2	1.9		127		31	2
XZ273	KJ060 ΔfumB	4	0.6		47		10
XZ276	KJ060 ΔfumB ΔfumAC	6	0.47	27	4	4	15
XZ276	KJ060 ΔfumB ΔfumAC	9	1.1		56		45
XZ277c	KJ060 ΔfumB ΔfumAC	2	1.07	1	71		35
XZ278	XZ277 ΔaspA	2	1.37	2	82		43
XZ280	XZ277 ΔaspC	2	1.17	1	78		31
XZ282	XZ277 ΔaceA	2	1.43	1	97		46

^aStrain KJ060 and derivatives also contain spontaneous mutations in pck and ptsI and affecting galP that were acquired during selection for improvements in growth (16, 17, 47, 49).

^bFermentations were carried out in NBS mineral salts medium with 2% glucose and 100 mM potassium bicarbonate (37°C, pH 7.0, 150 rpm). Anaerobiosis was achieved during growth with added bicarbonate to ensure an atmosphere of CO₂. The acetate concentration in the medium was measured at the end of fermentation. Abbreviations: Mal, malate; Suc, succinate; Pyr, pyruvate; Ace, acetate; For, formate.

^cSequential subculture (improvement in growth).