Bacterial Cycles and My Hobbies

By: Ezra Edelstein

Most hobbyists focus on what they can see: the beautiful scales on a fish and the golden crust on a sourdough loaf. However, after a couple of months of baking sourdough and keeping fish, I have found an interest in the fascinating science happening past the human eye. 

The most important “residents of my home” are the ones I cannot see, a group that spans from the nitrogen cycle, which keeps my tanks crystal clear, to the bacterial succession that gives my sourdough its flavor. 

Not only have I learned to be an aquarist and a baker, but also a bacteria caretaker. 

Fish tanks were my first introduction to seeing how small ecosystems maintain their balance. I was at Petco one day, just looking at the animals. I saw the fish tanks, and I just thought how peaceful they looked - the schooling fish swimming together, the shrimp eating algae. It was a very visible system with all the fish swimming harmoniously, helping maintain the tank. 

I just thought about how cool it would be to get my own. Little did I know about how many rabbit holes I would go down, learning more and more about aquariums and their unseen microecosystems. 

While I was learning about the various things I had to purchase (like a heater, filter, and light), I also learned about the nitrogen cycle, an entire process you must learn about before adding fish. 

Here's how the nitrogen cycle works: fish poop, and that poop breaks down into ammonia (NH₃). That ammonia is toxic to fish and is converted by beneficial bacteria into nitrites (NO₂), also toxic to fish. 

It is then converted into nitrates (NO₃), which are not toxic to fish in small amounts, and can be removed by water changes or plants like algae, which use them as nutrients for growth. 

I am not going to go over how to “cycle” a tank because that's not really what this article is about. If you're interested, I would encourage you to research this because not “cycling” your tank can kill your fish. It’s the main reason people quit the hobby.

Below is an image I made about the Nitrogen Cycle in an aquarium:

My fascination with bacterial cycles extended from fish tanks to my kitchen table, specifically to sourdough. 

My interest in sourdough began after being served amazing bread at my friend’s house, and I knew I wanted to make it at home. Again, another research project.  

For sourdough, the process begins with flour and water.  It is preferable to use a whole wheat or rye flour in the beginning, as these flours tend to be beneficial for the initial bacteria to thrive.  The entire process will use bacteria found naturally in the environment, which will create a micro-biome (ecosystem) composed of lactobacillus (which gives it a tangy taste) and yeast (for rising).  

Within the first few days of the starter creation, I was already able to see the starter begin to bubble and rise. This is known as a “false rise” because the dominant bacteria in the starter at this point are not yeast or lactobacillus but other more generalist bacteria, such as enterococcus and possibly even harmful bacteria like staphylococcus. 

These bacteria begin fermenting the sugars (carbohydrates) found in the flours. As they ferment, they lower the pH and create a significantly more acidic environment.  

This isn’t too well-planned out for them because this increase in pH makes the sourdough mix a hostile environment for the initial bacteria, and they die off.  The new lower pH, however, is a perfect environment for yeast and lactobacillus.  

Within about two weeks of regular feeding (more flour and water), the starter has a stable biome for both bacteria.  At this point, you should name your starter (ours is Dough-vid Hemlach); this makes it like a family pet that you remember to feed.  

The taste and rising power of your starter can be impacted by numerous environmental factors.  Different flour-to-water ratios will change how sour the dough will be and how strong the yeast will rise.  

Different flours allow different strains of yeast to thrive.  Even the biome present in your hands will change the composition of your starter.  

Below is a ChatGPT-made image to show Bacterial Succession in sourdough. ↓

While I find bacterial cycles interesting and enjoy learning about the sciences behind them, some may have other things that interest them. 

At the start, I had no idea how interested I could get in science. I want to encourage you to find something that interests you, whether that’s fish and sourdough, an instrument, or even a sport. 

There is so much to learn about really anything. Find something you love, dive into it, and have fun.