The industrial production of plants promoter like auxins is gaining interest, in consequence it is important to un- derstand the metabolism of the microorganisms involved and the optimal conditions for their industrial production. In this study the metabolic model of Bacillus subtilis was used to estimate intracellular fluxes and the robustness of the principal branching points of aerobic propionate metabolism for the 3-indoleacetic acid (IAA) production. The robustness analyzes of the metabolic network showed the enzymes that participate in the synthesis of erythrose 4-phosphate and glyceraldehyde 3-phosphate as possible limiting metabolites in the synthesis of IAA and might be a target for metabolic engineering strategies. The phenotype phase plane analysis allowed the identification of the opti- mal rate growth conditions to produce the auxin (less than 0.1 h ⁻¹).