The goal of defining a minimal genome involves finding the smallest number of genes to support cellular mitosis, the basic hallmark of life. The genes in a minimal genome are both necessary and sufficient for cellular growth.
Details:
Three distinct approaches can be taken towards this common goal, as relevant to E. coli.
1) Reduced Genome: the serial deletiion of large non-essential contigs and eventually all non-essential genes.
2) Synthetic Biology: all the genes are chosen, synthesized, assembled and inocuated into an DNA-less host, using sequences from many E. coli genes.
3) Comparative Genomics: progressively (a) identify the Common Core of genes shared among all E. coli and Shigella strains, (b) identify the Common Core that defines Gram(-) bacteria, (c) identify the most ancient genes in an ancient Minimal Gene Set (MGS) for all life, shedding light on the origin of genomes as the Last Universal Common Ancestor (LUCA).
