TABLE 2.

Effects of glcP::Tn10, ptsG::Tn10, and glcT::Tn10 mutations on the expression of a gntRK′-′lacZ fusion by various sugars^a

Repressing sugar	Response of strainb:
	ST100	ST141 (glcP)	ST143 (ptsG1)	ST144 (pstG2)	ST145 (glcT)
None	++ (690)	++ (670)	++ (720)	++ (730)	++
Glucose	− (110)	+ (340)	++ (750)	++ (740)	++
Mannitol	− (130)	− (120)	− (120)	− (140)	−
Sucrose	+/−	+	NDc	ND	ND
Fructose	−	−	ND	ND	ND
Glycerol	++	++	++	++	++

^aQualitative results were recorded after growth on solid media. Cells were streaked with 100 μl of 20-mg/ml X-Gal on 30-ml LB plates containing 1% gluconate as well as a 1% concentration of the repressing sugar indicated above and were incubated overnight at 37°C. Responses were recorded as follows: ++, dark blue; +, blue; +/−, pale blue; −, white. In the absence of gluconate, all colonies were white. Although ST145 is shown to exhibit responses comparable to those found for ST143 and ST144, a slightly lower response level was observed for gluconate-plus-glucose-grown ST145. Quantitative results (in parentheses) were recorded after growth in liquid media. Cells were grown and the experiments were conducted as described in Materials and Methods and by Chauvaux et al. (4). Values are expressed in Miller units/milligram of protein. The uninduced activity was 60 Miller units/mg of protein for all strains. 

^bGenes inserted on the mini-Tn10 transposon are in parentheses. 

^cND, not determined.