EFFECT OF ACETIC AND BUTYRIC ACIDS ON THE STABILITY OF SOLVENT AND SPORE FORMATION BY CLOSTRIDIUM-ACETOBUTYLICUM ATCC-824 DURING REPEATED SUBCULTURING

We studied the effect of serial transfers on solventogenesis capacity and spore-forming ability by Clostridium acetobutylicum ATCC 824 in tw o culture media. In reinforced clostridial medium (RCM), an abrupt dec rease of the ability to ferment glucose and produce solvent occurred a fter the 10th to 12th transfer and spore formation failed after the 25 th transfer. When 1.5 g/l of acetic and butyric acids were added to th e RCM, however, the capacity to produce a normal level of solvents was not lost, whereas spore-forming ability was lost after the 23rd trans fer. The shift from solventogenesis to acidogenesis did not occur in c hemically defined medium (CDM) even by the 40th transfer. The dramatic decrease of solventogenesis in the degenerate culture was coupled wit h acetate/butyrate CoA transferase and acetoacetate decarboxylase defi cient activities.