Solventogenic phase

The enzyme (16 inO Fig. 2.1) catalyzes the reversible transfer of the CoA moiety between an acyl-CoA and a carboxylic acid. The physiological reaction of the CoA-transferase, which is synthesized when cells enter the solventogenic phase, is to convert acetoacetyl-CoA into acetoacetate, with acetate or butyrate as the CoA-acceptor. Therefore, the activity of the CoA-transferase results in the reutilization of preformed acetate and butyrate, and the CoA-derivatives of the two acids enter the acid- or solvent-producing pathways. When butyrate is the CoA-acceptor, reaction 16 leads to the production of one acetone... 

Fig. 1 Biochemical pathways of ABE fermentation in C. acetobutylicum. Reactions prevailing during the acidogenic phase of the fcmnentation are shown with dotted arrows, and reactions prevailing during the solventogenic phase are displayed by thick arrows...

The solventogenic phase takes place during the stationary growth phase of the culture. 

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