Knockout of the high-coupling cytochrome aa3 oxidase reduces TCA cycle fluxes in Bacillus subtilis.

The metabolic impact of electron rerouting in the respiratory chain of Bacillus subtilis was quantitatively assessed during batch growth of quinol oxidase mutants by (13)C-tracer experiments. While disruption of the low-coupling cytochrome bd oxidase was without any apparent phenotype, deletion of the high-coupling cytochrome aa(3) 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 culture.