Employing microorganisms as chemists
When we think of chemistry, we usually think of something modern. Of laboratories with glassware, bubbling liquids, steam, smoke and a nasty smell. This might not be completely off, at least not from the labs I have seen. But chemistry can be more than that. Chemistry is about changing matter, right? About making certain compounds out of other compounds, by making them reaction with one another. Also, life is all about chemical reactions that happen all the time in all organisms. So if we are getting a specific organism to produce some compound for us, is that chemistry then? That’s the question that I want to discuss in this post and maybe share some insights into my days as a hobby brewer.
We have been using microorganisms for millennia without knowing it
Beer is pretty old. Bread is even older. Thank God they’re still around (says the German). Both these heavenly blessings need yeast in their production. Of course, people have not really been aware of this most of the time. The concept of microorganisms was only accepted in the 17th century. I just assume the low hygiene standards ensured that there were plenty of yeasts around to start fermentation. In each case, they’re doing something different. One amazing features of yeast is, that it can survive without oxygen, and then it produces ethanol. This is appreciated by a bunch of animals, amongst them a considerable number of humans, but also birds, moose and many more.
In the process of making beer (or other alcoholic beverages), we are using yeast to make that chemical reaction for us. There are also other fun side products, like carbon dioxide (CO2) that makes the drinks fizzy or methanol which makes you blind (less fun). These side products can be quite neat, but mainly, we want the yeast to make ethanol. This is almost like doing chemistry, just that the reaction is being performed by microorganisms trying to survive of what they have. In a similar fashion, this also applies to making wine. There are some differences, but overall it is the same idea.
For bread, this is a bit different, because there is oxygen that the yeast can feed off. So instead of alcohol, it produces carbon dioxide which makes the bread rise. To show how grateful we are, we kill the yeast when baking the bread after fermentation. Of course we don’t only bake the bread to kill the yeast. It is mainly for some rather physical than chemical processes, like expansion of the gases (so the dough rises further), evaporation of water (so it becomes dry) and destroying enzymes (so they stop performing reactions and yeast dies).
There are some more microorganisms that we use both for bread and beer, which are things like lactobacillus that produce interesting flavours, but these reactions are less specific demands than the production of ethanol and carbon dioxide.
Chemistry is still chemistry, even is if nature does it
In a way, humans have been making chemistry long before we even defined the field of chemistry, before we knew about atoms or molecules. Does it really matter if it is yeast that produces molecules for us, or if it is a isolated reaction in a roundbottom flask in a laboratory? I want to argue that it does not matter at all. Sure, today we would call it biotechnology and not chemistry, but the outcome is the same. In chemistry, we are using chemical reactions to create a certain compound, and with yeast, we are exploiting the fact that they have very specific pathways and the enzymes that catalyse those reactions are more efficient and specific than the chemistry we make in the lab. But the molecules that we get out in the end are the same. There are no differences, and so it doesn’t matter if certain drugs or nutritional supplements have been isolated from organisms or made in the lab. If there might be side effects we have from either of those two sources, might it be biological or synthetic, then those come from possible impurities or side products. It is often difficult to get substances completely pure, and both chemical synthesis and microbiological synthesis leaves side products behind. These side products can lead to effects that we might attribute to the molecule of interest being depending on where it comes from, but this is not actually the case. It is always the same molecule.
Sometimes you hear these claims from people that you have to be careful to only buy product XYZ from natural source, but not the ones that contain too much ‘chemistry’ (whatever that means exactly), or the ones that have been produced in genetically modified organisms. There are many things one can say about GMOs, about ‘chemistry’ in food production and so on, but at the end of the day, if you have a refined, pure substance, it is the same, no matter the source.
This is the important message for me to get across here. Chemistry is not about laboratories, smoke, artificial compounds, toxic waste and all that. Chemistry is about changing matter, and in many ways, we as humans have been doing this for millennia without understanding what we were doing at all. I find this pretty amazing and we should keep this in mind when we use the word chemistry, but actually mean artificial. Knowledge of chemistry provides us with the tools to make artificial compounds, but in itself, chemistry is the most natural thing there is.
Therefore, I raise my glass to Saccharomyces cerevisiae, the wonderful organism that secretively has been there all the time, making the chemistry that gave us beer, wine and bread.
Musical inspiration: The Golden Age
Photo by Tatiana Rodriguez on Unsplash
