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Why are Yeast Extracts and Yeast Peptones Complementary?

Probiotics, bioingredients, and biopharmaceutical players, dealing with microorganisms, face many challenges such as producing a satisfying yield of viable biomass or guaranteeing the target metabolite titer. Furthermore, many probiotic strains can be difficult to cultivate; ensuring they receive the optimal nutrients is essential. Within the category of yeast-based nutrients, yeast peptones and yeast extracts are two of the most used in industrial fermentation. In combination, yeast extracts and yeast peptones have proven to be one of the most suitable nitrogen sources to ensure microbial growth, and cell activity.


  • Yeast extracts provide a broad spectrum of nutrient content, while yeast peptones have a more specific nutrient profile composed primarily of only peptides and amino acids.
  • Both yeast extracts and peptones can be used in a wide range of microbiological culture media as nutrient sources.
  • Yeast peptones allow producers to target more specific nutritional needs allowing for more specific outcomes in biotechnology processes.
  • Yeast extract and yeast peptones can both be utilized for industrial-scale fermentation processes.
  • Yeast extracts and yeast peptones are complementary and bring additional value to specific applications.

How do yeast extracts and yeast peptones complement each other to answer a wide range of microorganisms’ nutritional needs?

Yeast extracts and yeast peptones are derived mainly from Saccharomyces cerevisiae and are concentrated versions of the soluble substances found in yeast cells.

Yeast extracts contain a plethora of beneficial compounds, including peptides, free amino acids, vitamins, and minerals. The extraction process involves breaking down the yeast cells (autolysis) and isolating the soluble components, leaving behind the cell walls and other insoluble materials. During the process of autolysis, the enzymes break down various components of the cell. Numerous intracellular components are released, including growth factors, nucleotides, compounds found in cell walls, and proteins are broken down into smaller. Afterward, the desired components are separated from the insoluble cell walls through centrifugation and washing. Yeast extracts are the concentrated nutrients of the yeast cell without the cell wall.

Yeast peptones, on the other hand, are protein hydrolysates designed to meet a specific composition of peptides. Enzymes will break down yeast proteins to a specific size and produce yeast peptones. As a result, yeast peptones contain a variety of peptides and amino acids that are essential for cell growth and complementary to yeast extracts.

Yeast extracts and yeast peptones’ nutrient content

Not all microorganisms have the same nutritional needs. Therefore, while yeast extracts provide a comprehensive array of nutrients, yeast peptones allow producers to target more specific nutritional needs for more specific outcomes in biotechnological processes. These specific outcomes include:

  • Cell viability
  • Metabolite production
  • Resistance to downstream processing


Yeast extracts provide a broader spectrum of nutrient content, which includes peptides, amino acids, vitamins, and minerals. By comparison, yeast peptones have a more specific nutrient profile based on the ratio of amino acids to different sized peptides.

Yeast extracts are often utilized in microbiological and cell culture media, as well as biotechnological applications as a rich source of nutrients including nitrogen and growth factors. As a complex mixture, yeast extracts imitate the variety of nutrients found in a natural living environment. A wide range of nutrients are provided by yeast extracts to promote cell growth. The elements found in yeast extracts can increase metabolic activity within cells, which helps cultivated cells thrive and produce.

Like yeast extracts, yeast peptones contain peptides and amino acids, which are necessary building blocks for the creation of proteins and other biological components. The wide variety of peptides in yeast peptone helps different cell types meet their nutritional needs. Yeast peptones can also add to the richness of the culture medium by adding amino acids and carbohydrates. Yeast peptones’ components increase metabolic activity in cells, promoting the best possible cell growth and productivity.

In industrial bioproduction processes, where microorganisms are cultivated to produce enzymes, biotherapeutics, or other bioproducts, yeast peptones’ nutrient-rich composition promotes high-density biomass and can increase the intended product’s production.

Yeast extracts and yeast peptones are complementary nutrient sources that can be used separately or in conjunction to achieve the best possible outcomes.

Complementary composition of yeast extracts and yeast peptones

Both yeast extracts and peptones are used in a broad range of microbiological culture media as essential nutrient sources to support the growth of bacteria, fungi, and other microorganisms.

Yeast extracts and yeast peptones are utilized in industrial-scale fermentation processes for the manufacture of a variety of biomass and metabolite productions. In this way, they both serve as nutrients to enhance biomass and for the growth and productivity of cells in bioreactors.

Yeast-based nutrients for optimized bacteria growth

An advantage in cell fitness has been demonstrated when cultivating probiotic strains on a medium that contains a combination of yeast extracts and yeast peptones. The unique and balanced composition of complex nutrients such as proteins, amino acids, and nucleic acids of yeast extracts and yeast peptones is key to boosting the viability and vitality of probiotic cultures. We have demonstrated a clear benefit of using this combination for the following strains: Bifidobacterium lactis, Lactobacillus acidophilus, and Lactobacillus reuteri.  These observations have been validated by our customers on a broad range of commercial lactic acid bacteria strains.

Benefits of using yeast peptones and yeast extracts

Yeast peptones

  • Improve viability and resistance to downstream process
  • Sustain the growth of microorganisms with complex nutritional requirements
  • Increase metabolite production

Yeast extracts

  • Fast growth and high biomass density for a broad range of microorganisms
  • Improve growth, acidification rate, and viability of lactic bacteria
  • Improve the growth and viability of oxygen-sensitive microorganisms

Find out more about yeast peptones as protein hydrolysates for the growth of microorganisms in an animal and allergen-free culture media.