Metabolic fluxes in recombinant Streptomyces lividans analyzed with 13C-based metabolic flux analysis

Abstract: Streptomyces lividans is an interesting host for the production of heterologous proteins. Expression of these foreign proteins often results in a metabolic burden leading to unsatisfactory yields. In this work, metabolic fluxes in Streptomyces lividans producing thermostable cellulase A are quantified. More insight in metabolic changes is acquired by estimating the fluxes in the central carbon metabolism by means of stationary 13 C-based metabolic flux analysis. Labelling was measured in proteinogenic amino acids, which were obtained from batch experiments with an optimally chosen mixture of uniformly labelled glucose and position one labelled glucose. The cellulase A producing strain shows an increased secretion of organic acids, while growth is less efficient. Intracellularly, an increase through the pentose phosphate pathway and the citric acid cycle is observed, which alters the redox potential. Production of NADH and NADPH is higher in the CelA-producing strain, although the need is expected to be lower.