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  • Alex Cloherty

The good things in life

Today's post is a short survey of some of the best things in life that we only have thanks to marvelous microbes!

1) Beer and wine

Have you ever wondered where the alcohol in beer and wine comes from? It is all from yeasts! These single-celled organisms eat up the sugar in grape juice (wine) or boiled grains (beer) and turn it into alcohol. The alcohol is actually a waste product of the yeasts 'eating'. But, the importance of yeasts to our favourite alcoholic drinks goes even further than just adding the alcohol. Using slightly different strains of yeasts gives the drink different flavours! For instance, you use a different yeast strain if you want to make an ale versus a lager.

2) Swiss cheese

The cheesiest of cheeses depends on bacteria for its characteristic holes! Propionibacterium feeds on lactic acid, which is made by other bacteria thriving on the sugars in the young cheese. Again, it is the waste products of our microbial friends that we love so much. After eating up the lactic acid, Propionibacterium releases carbon dioxide, the same gas that we exhale. This gas makes bubbles in the maturing cheese, and as the cheese hardens the bubbles are encased! Also like with beer, the choice microbe leaves a tasty flavour behind. Propionic acid, another waste product left behind by the Propionibacterium, gives Swiss cheese its yummy, nutty taste.

3) Chocolate

I bet this is one you didn't expect! But it's true: after cocoa beans are picked, they are allowed to ferment with a whole bouquet of microbes for about a week. A circle of life takes place within these seven days. The beans are first colonized by yeasts, which eat up sugars and leave behind alcohol as well as – you guessed it – chemicals that give the chocolate a tasty flavour. Like in kombucha, bacteria take the stage next and eat up some of the yeasts' waste products. The bacteria which grow on the cocoa beans are mostly species that produce lactic and acetic acids, and also leave behind various compounds that further enrich the delicious chocolatey flavour. These acid-producing bacteria then exit stage left and make way for spore-forming bacteria (Bacillus) that grow better on the now-acidic cocoa beans. Bacillus again adds to the brew of flavours. As these researchers put it, this "well-ordered microbial succession" is of "crucial importance" for achieving a good-quality chocolate.

4) Fro Yo

The trendy dessert on every street corner couldn't exist without bacteria! Lactobacillus and Streptococcus bacterial species eat the sugar in milk, lactose, and make lactic acid. This acid basically starts to curdle the milk: it makes it clot. Eventually, the little clots merge into one big clot with the soft, gel consistency that you know to be yogurt. From there, the only steps needed to get to Fro Yo are to freeze the old milk and bacterial waste, make it look pretty, and charge a lot for it!

5) Sourdough bread

Sourdough bread is a beautiful symbiosis of bacteria and yeast. The two different life forms live together in peace and stability, leaving us to wonder if the world would have been better off with only single-celled life on it...

... Back to the point. Lactobacilli are also the key bacteria in this tasty treat. The bacteria eat the sugars from the flour and leave behind acid as a waste. The yeasts eat this acid and leave behind carbon dioxide, which helps the dough rise! It's a perfect harmony.

I hope you get to try some of these tasty things in the next week - and give a thought to your microbial friends when you do!

Til next week,

- Alex

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