Metabolic Network Analysis of an Adipoyl-7-ADCA-Producing Strain of Penicillium chrysogenum: Elucidation of Adipate Degradation

An adipoyl-7-ADCA-producing, recombinant strain of Penicillium chrysogenum was characterized by metabolic network analysis, with special focus on the degradation of adipate and determination of the metabolic fluxes. Degradation of the side-chain precursor, adipate, causes an undesired consumption of adipate in the production of 7-ADCA. Using 13C-labeled glucose and measurement of metabolite labeling patterns, it was shown that adipate was degraded by β-oxidation to succinyl-CoA and acetyl-CoA. The labeling analysis indicated that degradation of adipate was taking place in the microbodies and the formed acetyl-CoA was metabolized in the glyoxylate shunt. This hypothesis was further substantiated by an enzyme assay, which showed activity of the key enzyme in the glyoxylate shunt. Flux estimations in two chemostat cultures, one with and one without adipate in the feed, revealed that degradation of adipate replaces the net anaplerotic reaction from pyruvate to oxaloacetate. Thus, with a combination of labeling experiments and enzyme assays, the pathway of adipate degradation was elucidated, and the effect of adipate degradation on the primary metabolism was quantified.