<i>agr</i> activity in the presence of hemoglobin.

<p>(A) Measurement of agr P3::GFP reporter activity in wildtype <i>S. aureus</i> (strain AH462) grown for 12 hours in TSBg or TSB supplemented with indicated concentrations of hemoglobin, myoglobin, or apohemoglobin. Error bars show standard error of the mean; * P<0.001 versus TSBg condition. (B) <i>agr</i> activation assay in the presence of hemoglobin. Reporter strain (AH462) was grown in 66% TSB with 0.2% glucose. At the beginning of logarithmic phase the cultures were supplemented with: 50 nM AIP, 50–300 nM AIP+5 ug/ml hemoglobin, or 50 nM AIP preincubated with hemoglobin that was subsequently immunoprecipitated. Error bars show standard error of the mean; * P<0.01 versus no addition control. (C) Effect of hemoglobin on agr activation on different <i>agr</i> types (502a – type 2, ATCC25933 –type 3), multiple <i>S. aureus agr</i> type 1 strains (LAC, FRI1164, Newman) and <i>isd</i> mutants. Error bars show standard deviation. (D) AIP induced biofilm detachment in the presence of hemoglobin. Biofilms were grown for 48 hours in TSB supplemented with 2.5 µg/ml of hemoglobin. After 48 hours, 2 ml of 25 µM AIP was added into the biofilm growth media.