E. coli K-12, being one of the best understood and thoroughly analyzed organisms, is the workhorse of genetic, biochemical, and systems biology research, as well as the platform of choice for numerous biotechnological applications. Genome minimization/remodeling is now a feasible approach to further enhance its beneficial characteristics for practical applications. Two genome engineering techniques, a lambda Red-mediated deletion method and a suicide (conditionally replicative) plasmid-based allele replacement procedure are presented here. These techniques utilize homologous recombination, and allow the rapid introduction of virtually any modifications in the genome.