Metabolic Imbalance and Sporulation in an Isocitrate Dehydrogenase Mutant of Bacillus subtilis

摘要: A Bacillus subtilis mutant with a deletion in the citC gene, encoding isocitrate dehydrogenase, third enzyme of tricarboxylic acid branch Krebs cycle, exhibited reduced growth yield broth medium and had greatly ability to sporulate compared wild type due block at stage I, i.e., failure form polar division septum. In early stationary phase, cells accumulated intracellular extracellular concentrations citrate that were least 15-fold higher than wild-type cells. The sporulation defects could be partially bypassed by major synthase gene (citZ), raising pH medium, or supplementation certain divalent cations, suggesting abnormal accumulation affects survival stationary-phase lowering chelating metal ions. While these genetic environmental alterations not sufficient allow majority cell population pass I (lack asymmetric septum formation), introduction sof-1 Spo0A transcription factor, when coupled reduction synthesis, restored expression spore formation nearly levels. Thus, primary factor inhibiting is abnormally high citrate, but relief this metabolic defect itself restore competence for sporulation.