Useful Products Engineered into E. coli “Poop” (Thank Goodness)


I can’t sit back and let the internet become saturated with misleading phrasing regarding by-products genetically engineered into E. coli metabolism. The latest sensation stems from the commercial production of the artificial sweetener aspartame. It was reported this week, well…read it for yourself (notice the language used):

This scientific jargon obfuscates (perhaps deliberately) a truly disturbing process:
1.) ‘Cloned microorganisms’ (which the patent later reveals to be genetically modified E. coli) are cultivated in tanks whose environments are tailored to help them thrive.
2.) The well-fed E. coli cultures defecate the proteins that contain the aspartic acid-phenylalanine amino acid segment needed to make aspartame.
3.) The proteins containing the Asp-Phe segments are ‘harvested’ (i.e. lab assistants collect the bacteria’s feces).
4.) The feces are then treated. This includes a process of methylation (adding an excess of the toxic alcohol, methanol, to the protected dipeptide).

While common sense dictates that this abomination doesn’t belong anywhere near our bodies, the patent’s authors made no secret about their belief that aspartame constitutes a safe and nutritious sweetener:

Source

It was picked up on the UPI under “Science News” with a headline reading:

The use of the words ‘poop’, ‘feces’, ‘defecate’, and ‘excrement’ is truly unfortunate and used to sensationalize the process. Natural News has an agenda, or several agendas. First they are against genetic modifications to living organisms even though almost all discoveries and breakthroughs in modern medicine can be contributed to some form of genetic modification. Second, they are publicly against the use of aspartame in commercial products.

The truth about E. coli ‘poop’

First, E. coli do not ‘poop’ in the sense a human can relate. These are single-celled organisms and are rather leaky to certain molecules naturally. E. coli produce by-products, not poop. Metabolic end products are considered waste to the E. coli cell, but these natural end products include carbon dioxide, hydrogen gas, acetate (vinegar), and water. Their poop doesn’t sound so bad now does it?

The evolution of E. coli ‘poop’

E. coli has been the organism of choice for decades in myriad research areas. Simple genetic modifications like gene deletion and gene insertion are the norm and can easily be performed in a lab. Scientists and doctors have used this technique to engineer novel strains of E. coli that tweaks their metabolism to produce useful products for the general public. One great example occurred in 1978 by Herbert Boyer who inserted the gene for human insulin into E. coli. Recombinant insulin was approved by the FDA in 1982 and is now the source of 70% of the insulin sold today.

Human growth factor is another by-product engineered into E. coli to treat different forms of dwarfism. For hemophiliacs, E. coli are utilized to produce missing clotting factors like tissue plasminogen activator and factor VIII. It should be noted that before producing these therapeutics in E. coli, they were harvested from cadavers. Patients with immunodeficiency can receive recombinant interferon, used to treat viral infections, produced in bacteria.

E. coli and other bacteria are used in other industries as well. They have been modified to produce large amounts of succinate, a precursor for the solvent 1,4-butanediol. It can then be used to make some plastics and even Spandex. E. coli are also used in the production of polyhydroxybutyrate, or PHB, for the production of plastics. E. coli is also used for production of polyamines for synthesis of polyamide plastics.

Over the past decade, a lot of research has taken place in the field of renewable energy. One approach to lessen our dependence on foreign oil is the microbial conversion of cellulosic (non-food) plant material into viable fuels like ethanol and butanol. This task has given E. coli and other microbes ‘poop potential’. Through genetic engineering and synthetic biology techniques, E. coli can produce large amounts of free fatty acids which are one catalytic step away from the same diesel fuel derived from petroleum. E. coli is also engineered to produce precursors for jet fuel.

In this post, I have focused on only one microbe, E. coli, since this was the bacterium sensationalized this week in the press.

Illustration of the world of synthetic biology: a new phase in science


animated bacteria, bioenergy, synthetic biology graphic
With novel technologies, it is becoming commonplace to manipulate microbes to acquire desired effects. Shown is a bacterium with foreign gene pathways (glowing) that enable this cell to efficiently produce a desired product.

First, there was biology which began in earnest in the 19th century. Then came molecular biology in the 1920s and the foundation of mutagenesis set forth by Herman Muller in 1927. Then, genetic engineering was first applied in 1972 the lab of Paul Berg. Finally, humans had the ability to manipulate living organisms in a specific, directed way. Fast forward 38 years to the announcement by J. Craig Venter that the first synthetic organism was created with a completely synthetic genome. However, Mother Nature is very particular about what exactly humans can do with respect to organismal manipulation. The naive thought that simple addition of genes from one organism into a more suitable organism would lead to theoretical, effective production of desired chemicals was soon the way of the albatros.

This is when scientists had to take a step back and rethink their strategy. They had to consider gene regulation (positive and negative feedback), build-up of secondary metabolites, toxicity of produced end products, etc. It wasn’t enough to add genes coding for enzymes necessary for desired chemical production. Through the advancements of bioinformatics, computation biology, and a nascent field called systems biology, scientists are just now starting to see the fruits of their labor.

Humor me; type in “engineering bacteria” into Google News. Take a look at the headlines that pop up in your browser. Look at the amazing advancements that are happening currently and imagine what is to come…