The microorganism Escherichia coli has a long history of use in the biotechnology industry and is still the microorganism of choice for most gene cloning experiments. Although E. coli is known to the general population for the infectious nature of one particular strain (0157:H7) few people are aware of how versatile and useful E. coli is to genetic research. There are several reasons E. coli became so widely used and is still a common host for recombinant DNA.

1. Genetic Simplicity

Bacteria make useful tools for genetic research because of their relatively small genome size compared to eukaryotes. E. coli cells only have about 4,400 genes whereas the human genome project has determined that humans contain approximately 30,000 genes. Also, bacteria, including E. coli, live their entire lifetime in a haploid state, with no second allele to mask the effects of mutations during protein engineering experiments.
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Weaver, R. and Hedrick, P. 1989. Genetics. Wm. C. Brown Publishers, Dubuque, IA, USA.
Madigan, M., Martinko, J. and Parker, J. 2000. Brock Biology of Micro-organisms, 9th ed. Prentice Hall, Upper Saddle River, NJ, USA.}