FIG. 4.

Expression of hem reporters in wild-type and hbrL strains in the presence and absence of exogenous hemin. Expression of hem reporters in the wild type (black bars) and hbrL strain JS163K (white bars) under semiaerobic conditions in the absence (-) and presence (+) of 30 μM hemin is shown. Values presented for each reporter represent triplicate measurements of biological replicates, with error bars representing standard deviations. Units are micromoles of ONPG hydrolyzed per minute per milligram of cellular protein. MU, Miller units.