This page was last updated March 2004. It provides links to data on essential genes in E. coli, and shows a short list of E. coli essential genes identified from the Neidhardt E. coli books (Neidhardt and Curtiss, 1996). I define essential genes as those genes which are required in WT strain MG1655 for the formation of colonies on solid rich medium within 24 hours of incubation at 37 degrees C. One method of establishing the essentiality of a gene is the the failure to obtain a null mutation in it. This approach is subject to both false postives and false negatives (see Gerdes et al. 2003 and Kang et al. 2004). In order to unequivocally identify an essential gene, a conditional lethal mutant must be made