The mass balance equations for all metabolites in the continuous C. acetobutylicum culture (see Fig 1).

In all equations, [ ] denotes metabolite concentration (mM), R refers to rate equations (mM h−1), r is the base enzyme production rate during acidogenesis (mM h−1), r+ is the upregulated enzyme production rate during solventogenesis (mM h−1), H is defined in Eq (3), D is the dilution rate (h−1), and [Gin] is the inlet glucose concentration (mM). The rate equations are given in Table 2.