Fig 1. An example illustrating that DoL does not reduce the overall metabolic burden.

(A) Basic idea of DoL: a two-step pathway converting a substrate S to a product P via the two reactions R₁ (catalyzed by enzyme E₁) and R2 (catalyzed by enzyme E₂) in a single strain is split into two parts each being performed by one dedicated strain. (B) Assuming an identical total amount of biomass, the metabolic burden (enzyme cost per biomass) is identical for the single strain and the DoL solution.