TABLE 7.

β-Galactosidase activity in WAM132 ΔmelR Δlac cells carrying KK43 or JK141 pmelAB::lac fusions and pJW15^a

MelR encoded by pJW15 derivative	β-Galactosidase activity
	KK43-pRW50		JK141-pRW50
	No melibiose	With melibiose	No melibiose	With melibiose
Wild type	23	1043	3	28
YD25 FY53 NI183 FS191	875	929	234	703

^aActivities are expressed in the units described by Miller and were determined using the Miller protocol (18). The data shown are the averages of at least four independent values that differed by no more than 10%. Cells were grown aerobically in defined medium with fructose as a carbon source either with or without 10 mM melibiose and were harvested in exponential phase at an optical density at 600 nm of ∼0.3.