TABLE 2.

α-Glucosidase and amylase activities of whole-cell extracts of strains^a

Strain	Growth substrate (carbon source)	Activityb (U/g of cell protein)
		α-Glucosidase	Amylase
BT5482	Glucose	2.2c	<0.6
	Maltose	60.3	49.1
BTΩsusR	Glucose	<0.6	<0.6
	Maltose	7.4	<0.6
BTΩsusB	Glucose	ND	ND
	Maltose	6.1	84.9
BTΩsusRΩmalR	Glucose	<0.6	<0.6
	Maltose	1.5	<0.6
BTΩmalR	Glucose	<0.6	<0.6
	Maltose	14.0	5.7
BTΩsusBΩmalR	Glucose	ND	ND
	Maltose	<0.6	4.5

^aFor this assay, strains were grown on minimal medium containing glucose or maltose (0.3%). 

^bThe substrates used to detect α-glucosidase and amylase activities are p-nitrophenyl-α-d-glucopyranoside and 4-nitrophenyl-α-d-maltoheptaoside-4,6-O-ethylidene, respectively. One unit of activity was defined as one micromole of p-nitrophenol liberated per minute. This experiment was conducted in duplicate, and the variation between replicates was <10%. ND, not determined. 

^cThere was some α-glucosidase activity from wild type on glucose, so there was a basal level expression of α-glucosidase on glucose.