The metabolic impact of electron rerouting in the respiratory chain of Bacillus subtilis was quantitatively assessed during batch growth of quinol oxidase mutants by 13C-tracer experiments. While disruption of the low-coupling cytochrome bd oxidase was without any apparent phenotype, deletion of the high-coupling cytochrome aa3 oxidase caused a severe reduction of tricarboxylic acid cycle fluxes and increased overflow metabolism. Since the product-corrected biomass yields were identical in mutants and parent, the results show that efficient ATP generation is not overly important for exponential growth of B. subtilis in batch cultur
