To ascertain whether slyA expression is regulated by RpoS , an isogenic rpoS S. typhimurium mutant was transformed with the slyA : : the level of b-galactosidase expression was determined .
To ascertain whether slyA expression is regulated by RpoS , an isogenic rpoS S. typhimurium mutant was transformed with the slyA : : lacZ plasmid was determined .