FIG. 4.

RH regulatory activity in the hyp-negative strain HF581. R. eutropha strains harboring the Φ(hoxK′-lacZ) fusion integrated into the norR2A2B2 gene region of the chromosome were grown in FGN medium in the absence (black bars) or in the presence (white bars) of hydrogen. Cells were harvested at an optical density at 436 nm of 8.0 ± 0.3 and the β-galactosidase activity was determined according to the protocol of Miller (28). Lane 1, HF573(pGE151); lane 2, HF581(pGE151); lane 3, HF582(pGE151); lane 4, HF581(pGE6); lane 5, HF581(pGE457).