The Sinorhizobium meliloti Lon protease is involved in regulating exopolysaccharide synthesis and is required for nondulation of alfalfa

While screening for Sinorhizobium melitoti Pho regulatory mutants, a transposon mutant was isolated that constitutively expressed higher levels of acid and alkaline phosphatase enzymes. This mutant was also found to form pseudonodules on alfalfa that were delayed in appearance relative to those formed by the wild-type strain, it contained few bacteroids, and it did not fix nitrogen.