Table 2.

Intracellular and extracellular citrate concentrations in citB mutant strains^b

Strain	Genotype	Samplea	Mean intracellular citrate concn (mg/liter) ± SD	Mean extracellular citrate concn (mg/liter) ± SD	pH of culture fluid
KBP94	Wild type	1	0.27 ± 0.09	3.3 ± 0.74	7.72
		2	0.22 ± 0.16	4.1 ± 0.22	8.28
		3	0.81 ± 0.57	5.7 ± 1.41	8.50
AWS174	citB null	1	10.7 ± 1.4	223 ± 20	6.81
		2	14.0 ± 1.4	323 ± 25	6.89
		3	6.8 ± 0.3	365 ± 14	6.89
KBP118	citB2	1	23.4 ± 0.7	255 ± 50	6.87
		2	9.0 ± 3.9	306 ± 39	6.94
		3	7.9 ± 1.9	349 ± 38	6.88
KBP81	citB7	1	15.0 ± 1.9	97 ± 1.6	6.64
		2	5.4 ± 2.0	108 ± 4.0	8.06
		3	5.3 ± 1.1	121 ± 16	8.35

^aB. subtilis cultures were sampled at three time points during stationary phase in DS medium. Strains KBP94, KBP118, and KBP81 were sampled at 4.3, 5.45, and 6.88 h of growth, and strain AWS174 was sampled at 3.92, 5.35, and 7.22 h of growth; all cultures reached the end of exponential growth phase at ∼4 h.

^bFor citrate samples, the means and standard deviations from 2 to 4 replicate assays are shown.