What is a symbiosis of bacteria and yeast?

Before understanding what a symbiosis of bacteria and yeast is, it is important to know what a symbiosis is and what is a yeast and a bacteria.

First of all, a symbiosis is defined as a biological, lasting and mutually beneficial association between two living organisms. On their side, bacteria and yeast are both living microorganisms. A bacteria is much smaller than a yeast. Bacteria can function either in environments with or without oxygen and we can find them almost everywhere such as in food, in the oceans, the air, the skin or in the gut. Bacteria are essential for the survival of the human body. For their part, yeasts are mainly found in foods such as bread, beer, wine and fermented drinks.

So, during the fermentation of the plant, a symbiosis between bacteria and yeast will take place. In order to carry out its fermentation, sugar, water and a SCOBY (Symbiotic culture of bacteria and yeasts) will be used.


By simplifying the process of bacteria and yeast symbiosis, this is what happens.
  • Since sucrose is a complex molecule, the yeasts will cut the sucrose to convert it into glucose and fructose. Thus, the yeasts will be able to feed on glucose and fructose.
  • They will then produce ethanol (alcohol) as well as carbon dioxide (bubbles) during the fermentation process.
  • The good bacteria will then ingest the ethanol and produce acetic acid, also known as vinegar. Vinegar has several antimicrobial properties which will help protect the culture against invading organisms from outside such as molds, yeasts or bacteria that could destroy the balance of the symbiosis.
  • Thus, the bacteria will create a biofilm which serves as their home and as a medium for the yeasts. This biofilm, also called a SCOBY (Symbiotic culture of bacteria and yeasts) will serve as a physical protection against external organisms, will be used to store resources to ensure their long-term survival and will promote better access to oxygen.
  • Bacteria will also create enzymes that deglycolyze complex molecules in order to use the glucose they contain for energy sources as well as to make the SCOBY. In doing so, they will make available molecules that are difficult to assimilate. Enzymes are breaking down complex foods into molecular units that are more easily assimilated by our bodies and by filtering out essential nutrients for the body.

This process is called a symbiosis of bacteria and yeasts since they are microorganisms working in symbiosis to create an ideal living environment. It is fortunate that this process facilitates the absorption of nutrients necessary for the health of the human body.