Frequently Asked Questions
Why E. coli and how can you learn about humans by studying bacteria?
Certain organisms, such as E. coli, have been used in research laboratories and in classrooms to advance our understanding of life and human diseases. These organisms become "model organisms" because of advantages in studying them. Model organisms are less costly, fewer ethical constraints are encountered using them, and, historically, more research data have been generated in the past. Model organisms are those that useful data sets have been already gathered to describe basic biological processes. And they are more amenable to asking certain questions due to their simplicity of structure and features. The biological insights gained from using model organisms have helped to cure human diseases and improve people's understanding of life.
Escherichia coli, a prokaryotic organism without a nuclear membrane, is a representative model organism often used in laboratories and classrooms. E. coli reproduces rapidly such that results for a number of experiments can be quickly obtained. E. coli was the organism used to elucidate the regulation of the lac operon in genetics. E. coli's ability to take up exogenous genetic material under the procedure known as DNA-mediated cell transformation has also made it a popular model for studies using recombinant DNA. Using recombinant DNA techniques, E. coli can be manipulated in research laboratories and in the classroom to produce any DNA, RNA or protein of interest. Also, it is easy to manipulate both genetically and biochemically. Most importantly, it shares fundamental characteristics, such as DNA and messenger RNA, with all other organisms, including humans. The value of E. coli in recombinant DNA makes it a good model organism to study genetic material.
Is the E. coli safe?
Escherichia coli, commonly known as E. coli, is a bacteria that lives in the large intestines of many animals including humans. E. coli is also found in the environment such as in soil and water. Normally, E. coli does not cause disease, it is a beneficial organism that is harmless to humans. They aid our digestion of certain foods and help our bodies produce necessary vitamins. There are a few strains of E. coli that are harmful to humans, these are the ones we hear of in the news when there has been an outbreak and people are getting sick. Over the last few years, all of the E. coli outbreaks in the news have been due to just one strain designated as O157:H7. It is important to emphasize that most strains of E. coli are in fact harmless to humans.
The two strains that will be used in the GeneSat satellite were both derived from the same isolate (E. coli K-12) that has been used in research labs for over 40 years. This is a very well studied strain that was modified such that it is unable to colonize the human large intestine. The K-12 strain and all the strains derived from it lack the ability to make certain proteins that are necessary for it's survival inside the large intestine. For this reason, these cells would not cause any harm to humans even if they were to ingest billions of cells. Any strains derived from K-12 are thus safe for use in the laboratory. The strains to be used in the GeneSat satellite are so safe that one of the strains was sold to us as part of a science activity kit designed for hands-on use by High School and Middle School students.
K-12 cells would also survive poorly if they were released into the environment. The EPA concluded in their report on K-12 dated February 1997 that "E. coli K-12 strains are very unlikely to pose a hazard to either animals, plants, or other microorganisms." These E. coli strains are now used in industrial settings where they are grown in high volumes and to high cell densities and have proven safe for both humans and the surrounding environment.