Fig 1.

marR⁺ complementation of GM9242 (marR). The marR gene was cloned into pBAD18 in which expression of the gene is reduced when the cell containing it is grown with glucose and expression is induced when the cell is grown in the presence of arabinose. Two constructs were used: the long marR ORF (L) as annotated in E. coli K-12 and the short ORF (S) as annotated in E. coli O157::H7 EDL933. The control strain (C) contained the vector plasmid. Cells grown overnight were diluted in ten-fold increments and 10 µl drops placed on appropriate medium. The plates were incubated overnight at 37°C. Cam = chloramphenicol, Tet = Tetracycline, Nal = Nalidixic acid.