E.coli’s use in GMOs: can you get E.coli poisoning?

posted in: Science | 30
E. coli bacteria viewed with electron microscopy. Image by Zeiss Microscopy via Flickr.
E. coli bacteria viewed with electron microscopy. Image by Zeiss Microscopy via Flickr.

For my first post on Biofortified, I’d like to share an account of an exchange that started on Twitter. It all began when I stumbled upon a doozy of a story, about how you can get E. coli poisoning from GMOs. The author outlines that E.coli is used during the course of genetic engineering to replicate DNA since it is highly prolific. But, the author highlights, E.coli is also able to transfer DNA laterally to and from other species. Then the author says: “It is possible that a mutated form of e-coli resulting from the cloning process used in creating GMOs could get into the gut of a person or animal that eats a transgenic plant.” The author then states that DuPont has partnered with the USDA in “identifying hard-to-identify strains of E.coli“. The theory comes full circle with the statement: “with this convenient partnership, even if harmful strains of e-coli relating to GMOs are discovered, it is likely that the public will never hear it from the USDA or DuPont.”

I feel like the author of this post missed out on an opportunity to write for the X-Files.

I then spent two days with the individuals posting these articles trying to discover how this could happen, but it never when beyond “the YUK factor” of using E.coli in generating our food. I even offered a 1 hour tutorial to share information on E.coli‘s use in genetic engineering, which got turned down. However, I did notice was that there were a couple of comments that probably made great memes for someone which got retweeted a whole bunch of times. They were mostly about how our babies are being exposed to E.coli and how our GMO corn is contaminated with E.coli. YUK.

Since my tutorial was turned down, I will write the facts about E.coli‘s use in genetic engineering here. I used E.coli, whose scientific name is Escherichia coli, quite a bit during grad school, but worked with it for the first time in one of my first or second year general biology classes in undergrad, where we made glow-in-the-dark bacteria. So here are some basic and irrefutable facts about E.coli.

  1. E.coli is used in the lab specifically because the strain used IS NOT HARMFUL. The non-virulent nature of the bacteria isn’t due to a mutation that might spontaneously arise to make it virulent again. There are entire genes that are different between virulent and non-virulent strains of E.coli. In fact, this paper looked at 61 different strains of E.coli and found that only 80% of their genomes are in common. That’s much less than the >95% that we share in common with chimps and closer to the amount we share with mice.
  2. E.coli and many other non-virulent bacteria live in our gut. This paper, which was examining the relative amount of bacteria in the gut of children recovering from cholera, found that E.coli accounts for approximately 40% of bacteria during recovery. These bacteria provide us with nutrients including vitamins K and B.
  3. E.coli is used in the lab because it grows like crazy. When it replicates it also copies its DNA.
  4. If you add the DNA that you’re interested in studying to E.coli‘s DNA, then that will also replicate.
  5. Why would you do this? Well, many procedures in the lab require a lot of DNA (by “a lot”, I actually mean microgram or nanogram quantities. But for a molecular biologist, that’s a lot). So how else can you get that much DNA that you’re interested in? The issue of amplifying and copying DNA is not unique to the process of making GMOs. So the technique of adding/removing DNA from E.coli, also known as cloning, is very common.
  6. Here’s an extremely simplistic overview of E.coli cloning (illustrated below): to add/remove DNA, you add an enzyme that cuts your gene of interest (known as “restriction enzyme”). Then you purify the piece that was cut. The way that your gene was cut will be in a specific pattern, similar to that of a puzzle piece. Then, you cut the bacterial DNA with the same enzyme so that the two puzzle pieces will fit together. The pieces get “glued” together with yet another enzyme known as a “ligase”. The glued piece of DNA goes into the bacteria, which then replicates. A few hours later… voila!! You have lots of bacteria that have lots of your DNA of interest.
  7. But then, and here’s the part that the authors of the lovely article above fail to mention, you have to get your DNA out of the E.coli. To get the DNA out of the bacteria, by definition, involves killing the bacteria. You pop the bacteria open, you clean up the goop, and you have bacterial DNA. THEN, you have to cut the DNA again so that you can get that piece of DNA that you were trying to amplify all along. So you leave the E.coli DNA behind, which again, was inconveniently left out in the article above. If you add DNA for entire genes to bacteria, sometimes they can actually produce that protein. This is the life-saving technology used to generate insulinmany synthetic vitamins, and drugs. In the case of insulin, the strain of bacteria used is E.coli. And despite my searches on the web, I’ve been unable to find a case of someone getting E.coli poisoning from insulin. Try telling a diabetic that there’s a YUK factor when it comes to their insulin.
The cloning process.
The cloning process.

I wrote this post during the week which celebrated International Women’s Day and I’m going to end with a very personal comment here:

This is to my fellow women. To all the brave moms out there doing their best, just like me. You do the ground breaking women in science an immense disservice by willingly choosing to remain ignorant on a topic and then perpetuating erroneous information. We women in science do what we do only because there was a Rosalind Franklin and a Nettie Stevens who paved the way for us. And you’re dropping shards of glass on that path. I kid you not. When you’re up-in-arms about babies being exposed to E.coli through GMOs, you spread misinformation, perhaps even prey on the susceptibilities of other moms, and you perpetuate decade-old stereotypes about gender. The specific one I refer to is depicted in this oft-used clip from the Simpsons, where Mrs. Lovejoy appears in town-hall meetings where progressive topics are addressed screaming “Think of the children!” and pulling her hair out. The stereotype is that we are emotionally driven creatures who sacrifice logic and common-sense when it comes to the safety of our children.

Aren’t we supposed to be helping each other out? Aren’t we supposed to be part of a brighter generation of women who can be moms AND be smart? So why is it that some women willingly turn down knowledge and choose to spew gibberish about how “GMOs are changing our evolution”? I find it extremely odd that you would be willing to trust a “scientific” article written by a correctional officer, but when a scientist tries to correct you, you dismiss the information. To paraphrase a recent interview I saw with Neil deGrasse Tyson, I can’t blame you if you are unaware of scientific facts and truths. That is probably just a factor of the education system that exists today. However (and this part is my own opinion, not Dr. Tyson’s), I can blame you if someone tries to correct you and educate you on these scientific truths and you choose to ignore them.

So let me make this abundantly clear: there is NOTHING, let me repeat that: NOTHING, written in that article about the risks and dangers of E.coli‘s use in genetic engineering that is accurate. If you want to argue against GMOs, please use arguments that are evidence based and do not propagate scientific illiteracy. Think of the children!

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Layla Parker-Katiraee holds a PhD in Molecular Genetics from the University of Toronto and a Bachelors degree in biochemistry from the University of Western Ontario. She is currently a Staff Scientist in DNA Sequencing Product Development. All views and opinions expressed are her own.