TABLE 2.

RhuI upregulates bhuR::phoA expression in B. avium Pho20^a

Plasmid	RhuI expression	Alkaline phosphatase activityb
		Fe-replete	Fe-limited
pRK415	−	0.003 (0.0)	0.137 (0.0)
pERM26	+	1.127 (0.1)*	3.087 (0.1)*

^aPlasmids were conjugated into B. avium Pho20, which contains a bhuR::phoA translational fusion reporter in the bhu locus. Cells were cultured in Fe-replete BHI broth (100 μM EDDHA and 144 μM FeSO₄) or in Fe-limited BHI broth (100 μM EDDHA). 

^bAlkaline phosphatase activity was determined by the colorimetric NPP assay (35). The mean and standard deviation (in parentheses) are shown for each value. Activity is reported as micromoles of NPP hydrolyzed per minute per OD₆₀₀ unit. Asterisks indicate the values that are significantly different (P < 0.05) from the value for the vector control when each strain is cultured under identical conditions, as determined by the Student t test.