So You Want to Brew! Our intro-to-homebrewing course – Part Two: Microorganisms

On this episode of Doin’ the Most, we’re in part two of our series – So You Want to Brew?

Fermentation is as complex as is it rudimentary. Getting started can feel like a complete whirlwind from the first moment you type it in the search bar: How to make beer at home.

A lot of folks come to our YouTube channel looking for information on how to make mead or wine. And we try to be very intentional in breaking down the process in our brewing videos – but we also wanted to make some real bare-bones content for newer brewers that lays everything out simply. So we’ve put together this introductory course to fermentation. We’re excited to share this content and contribute to the amazing body of work cultivated by other brewing content creators. You may want to check out the first video in this series, which focuses on homebrewing equipment. In this episode, though, we’re talking microorganisms!

Real quick, let’s check out the ground rules we set at the beginning:

  1. This channel is more focused on meads and wine than beers, but the majority of what is presented in this guide will also be relevant when making beer. However, to simplify our language, “must” will be used throughout instead of “wort.”
  2. Also, most folks don’t consider wines or meads to be “brewed” – that’s fine, but we’re going to lump all home fermentations of alcoholic beverages into the “homebrew” category. This will included referring to fermentations that have completed primary as “brews.”


The little lovelies that make fermentation possible. They are our friends – our little pets who make alcohol for us. And on the microorganisms’ scale, there is a heck of a lot happening down there.

As a homebrewer, yeast is the microorganism we appreciate the most. Yeast are eukaryotes just like us. However, unlike us, yeast are single-celled microorganisms classified as fungi. There are no less than 1,500 species of yeast on Earth, with saccharomyces cerevisiae being one of the most cherished – as it converts carbohydrates to both carbon dioxide and alcohols during fermentation.

Commercially, pre-portioned and pure samples of yeast strains are available in both liquid and dry preparations. The preparation you purchase may be dependent on the strain and style you’re brewing. Realistically, most commercial brewing yeasts can be lumped into two categories for simplification: beer and wine, with champagne yeasts being a prominent subcategory under wine.

Beer yeasts are generally put into two categories: ale yeast which are “top-fermenting” and lager yeast which are “bottom-fermenting.” There are various strains within these categories, all responding differently to temperature and nutrition to create different flavor compounds for different styles. Beer yeasts tend to have a lower alcohol tolerance than wine yeasts, meaning they can become stressed or even tap out when fermenting higher gravity musts.

Wine yeasts are typically characterized by having higher alcohol tolerances. Strains have been specialized for all kinds of different purposes, such as color extraction for red wine yeasts or those that produce flavor compounds which complement the specific characteristics of a certain grape. And while there are a few yeast strains bred specifically for mead, often wine yeasts are just as, if not more effective, at drawing out the delicate flavors of the honey.

Champagne yeasts are typically super-charged wine yeasts. Often, they are killers intended for consistent, high-ABV fermentation.  Sparkling wines are usually fermented with a different strain of wine yeast, then champagne yeasts are introduced during the bottling process.  This affords for consistent and relatively predictable carbonation of the sparkling wine after a yeast more suitable for flavor production is used during the outset. Essentially, champagne yeasts are intended to garner good bubbles, not necessarily good flavors.  However, many homebrewers have found them useful for consistent fermentation at very high gravities – meaning ABV of 18% or higher is possible.

Let’s check out the anatomy of a yeast. Where do they come from?

Now, we covered how yeasts are naturally occurring organisms. And how strains have been bred to perform various functions. But they also exist all around in the wild – including living on fruits like grapes. In fact, most vintners rely on the natural yeasts on the grapes to do their fermentations.

They’re weirdly shaped little dudes, single-celled, using buds to reproduce. They take in sugars like sucrose, glucose, and fructose, metabolize them, and excrete carbon dioxide and alcohols.

There are some other yeasts and bacterial cultures often used in fermentations.

Brettanomyces is a non-spore forming genus of yeast in the family Saccharomycetaceae, and is often referred to simply as “Brett”. It typically produces funk -filled and tart flavor profiles that complement fruity flavors in a must. Brett is great at producing acetic acid, a main component in vinegar. Experimentation with brett is usually more of a venture for fairly experienced brewers.

Oenococcus oeni is a bacteria that can be introduced to induce malolactic fermentation. Malolactic fermentation is the conversion of malic acid to lactic acid, which is a “softer” tasting acid. Lactic acid is less acidic than malic acid, which can improve the roundness of a brew’s flavor profile. Malolactic fermentation can be a great in-tandem fermentation for fruity reds and berry wines when conducted alongside fermentation with a complementary yeast.

Lactobacillus are another lactic acid bacteria similar to Oenococcus oeni, and can be a source of enzymes for wine aroma. In my experiments with Lactobacillus, though, it can be very finicky and throw some relatively disgusting off-flavors if not watched like a hawk.


Microorganisms are things that we love. However, there are enough of them out there that can create adverse effects – looking at you, acetobacter – you must make sure everything that comes in contact with your must is sanitized completely.

No-rinse sanitizing solutions are the best answer for this problem.

We recommend the acid-based sanitizer Star San. Star San is a self-foaming bactericide and fungicide that comes in a concentrated form. Simply mix with the appropriate amount of water, and you’re ready to sanitize your equipment. Using it in a spray bottle makes misting it a breeze.

There are plenty of other means of sanitizing, including powdered acid sanitizers, Iodophor (which is iodine-based), and even bleach-based recipes – but those can require a long soak.

Whatever you choose, sanitizing solution is a must-have for homebrewing! It is critical that only the microorganisms in your must are the ones you allowed to be in there. Wild buggies can spoil a whole batch!

Well that’s it for part two of “So you want to brew” – in part three we will discuss what happens when you put your yeast to work in fermentation.


Do you have any insights to add regarding the microorganisms in fermentation? Let us know in the comments.  There is so much nuance that can be obtained through different yeasts and cultures – and so much that can be learned about how they all respond to different conditions. We’d love to know what your favorite yeasts are! YSee ya next time, when we talk FERMENTATION!

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