Regulation of Phosphate Assimilation in Rhizobium (Sinorhizobium) meliloti

We report the isolation of phoB and phoU mutants of the bacterium Rhizobium (Sinorhizobium) meliloti. These mutants form N2-fixing nodules on the roots of alfalfa plants. R. meliloti mutants defective in the phoCDET (ndvF) encoded phosphate transport system grow slowly in media containing 2 mM Pi, and form nodules which fail to fix nitrogen (Fix-). We show that the transfer of phoB or phoU insertion mutations into phoC mutant strains restores …