TABLE 1.

Effects of lactose, glucose, and IPTG on β-galactosidase production in wild-type B. megaterium and an mbgA mutant

B. megaterium strain	Additiona	Mean β-galactosidase activityb (U/ml) ± SD
Wild type	None	0.31 ± 0.03
	Lac	5.54 ± 0.39
	Lac + Glu	0.22 ± 0.02
	1 mM IPTG	0.39 ± 0.04
	6 mM IPTG	0.35 ± 0.05
mbgA mutant	None	0.15 ± 0.02
	Lac	0.21 ± 0.02

^aAbbreviations: Lac, lactose; Glu, glucose. 

^bB. megaterium cells were grown in LB medium to an optical density at 600 nm of 0.6 in the absence or presence of 2% sugar or IPTG, as specified. β-Galactosidase activities of the chloroform-treated B. megaterium cells were determined as described previously (20). Each value is the mean of four experiments.