LAUSR

BackgroundRecently, we showed that steady-state continuous cultures of S. stipitis follow the principles of growth on mixture of two complementary substrates. More precisely, when such cultures are fed with progressively higher concentrations of glucose sf at fixed dilution rate D = 0.1 h−1, oxygen mass-transfer coefficient kla = 50 h−1, and oxygen solubility $$c_{\text{o}}^{*}$$co∗, they transition from glucose- to oxygen-limited growth through an intermediate dual-limited regime in which both glucose and oxygen are limiting, and ethanol is produced without loss of glucose. It is, therefore, of considerable interest to characterize the dual-limited regime. We found that the dual-limited regime occurs precisely when the operating parameters D, sf, kla, and $$c_{\text{o}}^{*}$$co∗ satisfy the relation $$Y_{\text{os}} < Ds_{\text{f}} /\left( {k_{\text{l}} a \cdot c_{\text{o}}^{*} } \right) < Y_{\text{os}}^{\prime }$$Yos