The Rhizobium etli poly-beta-hydroxybutyrate synthase (PhaC) mutant SAM100 grows poorly with pyruvate as the carbon source. The inactivation of aniA, encoding a global carbon flux regulator, in SAM100 restores growth of the resulting double mutant (VEM58) on pyruvate. Pyruvate carboxylase (PYC) activity, pyc gene transcription, and holoenzyme content, which were low in SAM100, were restored in strain VEM58. The genetically engineered overexpression of PYC in SAM100 also allowed its growth on pyruvate. The possible relation between AniA, pyc transcription, and reduced-nucleotide levels is discussed.