Comparative analysis of gene importance in Escherichia coli across growth conditions

As complete genome synthesis becomes more accessible, determining which genes should be included in a synthetic genome to provide robust growth becomes increasingly critical. This study demonstrates that gene contributions to fitness are not binary and depend strongly on environmental conditions. By analyzing E. coli transposon mutants grown in different media over multiple passages using an innovative sliding-window approach, we identified genes generally important for fitness and others that are condition-specific or have a reduced, yet measurable, impact on fitness. Using these gene sets, we formulated medium-specific gene modules that combine essential and fitness-contributing genes to support robust growth in each environment. This improved understanding takes us beyond static gene lists and toward dynamic, context-aware genome design tailored for specific applications.