Limbic Signal: Eau De Coli

Thursday, October 25, 2018

Eau De Coli

I should begin by pointing out that I am not a perfumer. Actually I should begin by pointing out that there is such a thing as bacteria art, also called agar art, as seen above. Let me start again – I am not a perfumer; I am a writer interested in the language of smells. Obviously, perfume is a big part of that. But when I learn that bacteria are used to make perfumes it comes as a surprise to me, and I feel like I missed something. (And when I had been an art teacher for over ten years and I realize there’s such a thing as bacteria art, I also feel like I missed something, except for the fact that I only discovered radiation art a month ago.)

Apparently, fragrance experts are also a bit surprised. Engineering microorganisms to make specific odorous chemicals are a new addition to the typical methods of expression, steam distillation, and solvent extraction.

It all started with a project done by a scientist named Reshma Shetty and a team at MIT. I'm almost as excited about the name as I am the project - it was called Eau De Coli, after the dignified Escherichia coli. And it can be translated as "water of the colon."

E. coli isn't just for making you sick, or for making Chipotle go Chapter 11, it's also for scientists trying to research bacteria. E. coli is the model organism for scientific study, probably because of the compendium of literature already amassed due to its dangerous nature, and maybe just because it's easy to work with.

Regardless, dissertation-defending Shetty and her group engineered this archetypal organism to be a smell-generating machine. Usually E. coli smells like crap, literally, so they first had to find a mutant strain that had no genetic propensity for producing that smell. (This smell comes from the molecule Indole, by the way, and is related to Skatole, which doesn't sound like "skat" by accident.)

The next part was right out of a science fiction novel. They found enzymes that would produce the smells of wintergreen (methyl salicylate) and banana (isoamyl acetate), and they programmed the bacteria to produce those chemicals. So now, instead of smelling like crap, they smell like mint and bananas!

This is called odor engineering - a kind of genetic engineering that is used to make odor chemicals from bacteria. The researcher here, Dr. Shetty, suggests using this technique to probe bacteria at an industrial scale. Imagine you engineer the bacteria in your business to produce different smells at different stages in its metabolism. You could then tell what the bacteria are doing just by sniffing them.

Then there's others who are simply coaxing bacteria to produce otherwise difficult fragrance chemicals. Folks at the Joint BioEnergy Institute at Lawrence Berkeley Labs were originally trying to get bacteria to make biofuels. But after they accidentally discovered a way to make methyl ketones, the fragrance industry perked up.

Combining genetic-metabolic engineering and fragrance production may be a breakthrough for the industry. Now if only we could find a way to engineer ourselves not to secrete isovaleric acid from the soles of our feet!

Notes:

Dr. Shetty's genetic odor engineering Eau de Coli project:

Shetty, R. P. Applying Engineering Principles to the Design and Construction of Transcriptional Devices. Department of Biological Engineering, MIT (2008).

http://hdl.handle.net/1721.1/41843

Lawrence Berkeley Labs bioengineering efforts:

From Petri Dish to Perfume, Berkeley Science Review

http://berkeleysciencereview.com/article/from-petri-dish-to-perfume/

Post Script:

While I research odor engineering, I find some things that fall well outside the realm of fragrance.

Odor Science & Engineering, Inc. will research environments that stink and develop products that don't. Instead of using bacteria, they rely on good ol' nose megaphones (see below, a screenshot from their site.)