Initiation of solvent production,clostridial stage and endospore formation in Clostridium acetobutylicum P262

Summary A minimal medium was used to investigate the triggers regulating the initiation of solvent production and differentiation in Clostridium acetobutylicum P262. The accumulation of acid end-products caused the inhibition of cell division and the initiation of solvent production and cell differentiation. Initiation only occurred with a narrow pH range. Glucose or ammonium limited cultures failed to achieve the necessary threshold of acid end-products and solvent production and differentiation were not initiated. The addition of acid end-products or ammonium to cultures containing suboptimal levels of glucose or nitrogen respectively, enhanced solvent production. Resuspension of cells in media containing the threshold level of acid end-products and residual glucose induced endospore formation. Glucose or ammonium limitation did not induce sporulation and there was a requirement for glucose and ammonium during solventogenesis and endospore formation. Initiation of solvent production and clostridial stage formation were essential for sporulation. The induction of endospore formation in C. acetobutylicum P262 differs from that in the aerobic endospore forming bacteria where sporulation is initiated by nutrient starvation.