Low growth rates were also characterized by the induction of multiple pathways for acetate and pyruvate metabolism, indicating metabolic redundancy . For example, proteins initiating acetate consumption, acetate kinase (Gmet 1034) and the ATP-consuming acetate-CoA ligase (Gmet 2340) were more abundant at low growth rates in the acetate-limited retentostats compared to batch culture (Fig. 4). Increased demand for pyruvate at low growth rates was reflected in expression of phosphoenolpyruvate synthase (Gmet 0770) and the acetyl-CoA synthesizing component of pyruvate dehydrogenase (Gmet 2510), as well as increased abundance
of the ATP-consuming pyruvate carboxylase (Gmet 0816) (Fig. 4).