Figure 2. Engineering the interplay between exogenous circuits and the metabolism of the chassis.

(A) Scheme depicting current methods of obtaining whole-cell models from genomic information. Metabolic reconstructions are constrained by incorporating networks of regulatory interactions and the investment of cellular resources (e.g. ATP, nucleotides, amino acids, RNAP and ribosomes) in the transcription and translation of the enzymes responsible for the metabolic reactions. (B) Extremophilic bacteria are endowed with a versatile metabolism that allows investing energy and resources in the mechanisms needed to survive harsh conditions (left-hand panel). In the absence of environmental stressors those resources are invested in overflow fluxes that could be capitalized for the production of alternative products (right-hand panel).