TABLE 3.

Regulation of B. subtilis pyrG-lacZ fusions by pyrimidines

Strain	Genetic background	Addition(s) to minimal mediuma	Doubling time (min)	β-Galactosidase activity (Miller units)
QM201	Wild type	None	36	68 ± 3
		Urd, Ura	38	65 ± 7
		Cyd	36	50 ± 2
QM202	ΔpyrR	None	47	50 ± 1
		Urd, Ura	48	50 ± 2
		Cyd	45	40 ± 4
QM203	ΔpyrDII	None	58	110 ± 15
		Urd, Ura	37	55 ± 3
		Cyd	38	40 ± 4
QM204	ΔpyrDIIcdd	None	66	130 ± 8
		Urd, Ura	38	70 ± 8
		Cyd	58	17 ± 3
QM205	pyrB::spec	Orotate	85	830 ± 190
		Urd, Ura	39	55 ± 8
		Cyd	38	45 ± 8
QM206	pyrG::erm	Cyd	48	440 ± 8
		Cyd, 10 μg/ml	88	700 ± 75
		Cyd, 10 μg/ml; Urd	180	1,900 ± 60
		Cyd, 10 μg/ml; Ura	101	1,300 ± 120

^aUnless specified, cytidine (Cyd) was used at 200 μg/ml, uridine (Urd) was used at 50 μg/ml, and uracil (Ura) was used at 50 μg/ml.