β-Glucuronidase activities of the S. meliloti iolA-gusA reporter gene fusion in the iolA mutant strain. The WIOLA mutant was grown in minimal medium containing myo-inositol (MI), glycerol (Gly), glucose (Glu), succinate (Suc), or combinations thereof at a final concentration of 0.2% as the carbon source. Bars represent the average of two independent experiments, and error bars denote ±SEM.