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  • Alex Cloherty


Welcome back (after a long pause – PhDs are harder than I thought) to Microbial Mondays!

This post is inspired by three recent occurrences in my life. The first, is that for the last two weeks I’ve been producing HIV in the lab using E. coli.

… Huh?

Yep, that’s right, I have been using E. coli bacteria to make new HIV virus that I can use in my experiments. The second occurrence that this post is inspired by took place right after I told my co-presenter at a fermentation workshop that I facilitated last week about my little E. coli HIV factories. She exclaimed, “Whaaaaat?! That’s crazy!” And she was right. It’s totally nuts that we humans have figured out how to use bacteria as tiny factories (bactories... get it?) to produce (almost) anything we want to make.

And now, we come to the third occurrence that spurred the writing of this article. At that same fermenting workshop, I picked up a beautiful, full-grown Kombucha SCOBY to show around, and was inevitably greeted by a chorus of, "Ewwwww!!!!" And that was the final push to write this article.

Today’s post is dedicated to the amazing use of bacteria as biotechnology, and a testament to how bacteria aren't just gross, weird, slimy, "Ewwww"-inducing microorganisms. They are so much more, and a vital tool to biologists all across the globe!

Biotech vs. Biotechno, ft. dead-e.-c0li

So how does it work? The process starts, as pretty much all biological processes do, with a piece of DNA. Like us, bacteria have a genome. However, unlike that of humans, the genome of bacteria is somewhat adjustable. Think of it this way: as a human, once you're born, you're stuck with the genes you've got. As a bacterium, you likely have extra little bits of DNA that aren't attached to your main genome. These little extra DNA bits are called plasmids.

To bacteria, plasmids are like little extra toolkits that they can pull out in times of need. For example, imagine that you are a bacterium that has suddenly found itself in a new environment where its usual foodstuff is entirely absent, but other substances, like toluene for instance are readily available. Your species doesn't usually eat toluene, but If you are lucky enough to carry enough to carry a so-called "metabolic" plasmid, those extra genes could serve as your toolkit for breaking down (i.e. eating) toluene! This is kind of like evolution on the (microscopically) small scale: the bacteria that survive being thrown into this new, toluene-rich environment will survive, and will be able to pass on that toluene-toolkit plasmid. The big difference between this type of "evolution" and evolution in the way that we normally think about it, is that these bacteria probably won't merely pass on the plasmid to their direct offspring. They can also pass it around to their friends.

You can picture it like this: you're a brunette, and your friend, a blonde, has decided that she wants to go brunette, too. No need for hair dye! She just reaches her hand out, pinches off a bit of your brunette DNA from some of your cells, rubs it on her head, and starts growing brown hair.

This ability of plasmids to be shared around is incredibly important in modern biology and medicine. You can start to see why if you picture that environment that the bacterial you was thrown into earlier was rich in not toluene, but rather in an antibiotic. If you or one of your bacterial friends has the right plasmid toolkit to break apart that antibiotic, the human that you're growing in has very bad luck. Indeed, bacteria sharing around plasmids that encode genes for antibiotic resistance is one of the main ways that antibiotic resistance spreads.

Luckily, it's not all bad news with plasmids. To get back to the reason I started writing this story, plasmids can also be used as a tool! Looking back, how do you think I got bacteria to produce HIV for me in the lab? That's right, I stuck a plasmid in them! The genes for HIV were encoded in this plasmid, just like a blueprint. Of course, HIV is not the only thing we can put on plasmid blueprints for bacterial factories. For instance, at another lab that I worked in, we used the same system to get bacteria to mass-produce a protein we wanted to study. This particular protein is under investigation to be included in a life-saving vaccine against whooping cough. Biologists all over the world use this same system to mass-produce molecules.

So, next time somebody says, "Ewwww!" when you show them some bacteria, you can remind them that in some ways, they seem more evolved than us!

Until next time,


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