TABLE 4.

PDHC activity in cell extracts from exponentially growing cultures in media with a_w adjusted with various humectants^a

Humectant	aw	PDHC activityb	C sourcec
Sucrose	0.94	0.86 ± 0.4	Yes
Glucose	0.94	<0.1	Yes
Mannose	0.95	0.77 ± 0.07	Yes
Fructose	0.94	<0.1	Yes
Glycerol	0.95	1.1 ± 0.2	Yes
PEG 8000	0.96	2.6 ± 0.4	No
Glycine betaine	0.94	4.7 ± 0.5	No

^aCells were grown in TSB media.

^bPDHC activity is defined in footnote c of Table 3, where the activity value (1.6 ± 0.3) for non-osmotically stressed cultures (a_w, 0.996) is also given. Values shown are averages obtained from duplicate measurements from at least two replicate experiments ± standard deviations.

^cExperimentally determined as the presence (yes) or absence (no) of growth of S. aureus in DFM with the indicated humectant added as the only available carbon source at a concentration of 0.5% (wt/vol).