By DRS. DAVID NIESEL AND NORBERT HERZOG
It is small, we all live with it and it is arguably the best studied organism on the planet. Yes, more than humans! Some forms of it can cause serious disease and scientists have been investigating all aspects of it for more than 125 years. It is present in the intestinal tract of every human and is commonly found in the environment. It is an important biomarker of fecal contamination. What I am talking about of course is Escherichia coli or E. coli.
This bacterium has been a powerhouse for biological discovery for over a century. It has been used by molecular biologists since the 1950s to understand genes and to develop the molecular biological tools that have allowed us to modify genes and advance genetic engineering.
The cloning of genes was first accomplished in E. coli. Human insulin was first made as a recombinant molecule produced in E. coli, and this was followed by a multitude of other molecules that have become today’s therapeutics and vaccines. E. coli was one of the first bacteria whose entire sequence of 4.6 million base pairs — the alphabet of DNA, has been described. Thousands of scientists have worked with this bacterium that provides a safe “work bench” for genetic manipulation. The E. coli laboratory strains can no longer survive outside the laboratory or in the intestinal tract.
E. coli is easy to grow in the laboratory and grows rapidly. A broth culture inoculated with literally a handful of these bacteria can grow to tens of billions overnight because this microbe divides into two daughter cells every 20 minutes. Talk about the lack of birth control.
Now scientists at Harvard are suggesting that the growth rate of E. coli is too slow for some commercial uses. They are promoting the use of one of the most rapidly growing bacteria known called Vibrio natriegens. Recent work positions it to become an attractive alternative to E. coli. Ding dong, the king of molecular biology — E. coli is dead! Well not quite yet.
Vibrio natriegens is found naturally in salt marshes. It takes only 7 to 10 minutes to reproduce in standard lab media which is at least twice as fast as E. coli. Some believe that this microbe could be coaxed to grow even faster once optimal growth conditions are better defined. The genome of this microbe has been completely sequenced. Unlike many bacteria, it has two chromosomes. One has 3.2 million base pairs — and the other has 1.9 million base pairs of DNA. Tools for moving recombinant DNA into this microbe and genome editing have been developed; positioning it for an expanded future use.
So is king coli dead? Not yet, genetic manipulations in E coli are likely to continue for years. Because of its superb growth rate, Vibrio natriegens could soon find a place in large scale manufacturing operations where a twice as fast growth rate could contribute to big savings for commercial applications.
Medical Discovery News is a weekly radio and print broadcast highlighting medical and scientific breakthroughs hosted by professor emeritus Norbert Herzog and professor David Niesel, biomedical scientists at the University of Texas Medical Branch at Galveston. Learn more at www.medicaldiscoverynews.com.