Genetically Engineered Chymosin

  • Chymosin is a key ingredient in cheese, ice cream, and other dairy products. Chymosin is an enzyme that makes milk curdle, an important step in the cheese making process. This enzyme occurs naturally in the stomachs of some animals.

  • Cheesemakers used to get chymosin from calf stomachs. But calf stomachs are not a practical source for large quantities of chymosin, and cheesemakers need a lot! To create a sizable steady supply, scientists searched for ways the enzyme could be produced in mass quantities.

  • Genetic engineering provides an alternative process for producing chymosin. Scientists take cells from a calf's stomach, and isolate the genes responsible for producing chymosin. Those genes are then spliced into the genetic material of yeast cells. The yeast cells with the calf genes now produce chymosin. Yeast can easily be grown in industrial size quantities to get large amounts of chymosin.

  • Chymosin was the first food product derived from biotechnology to be approved by the Food and Drug Administration (FDA). Genetically engineered chymosin allows vegetarians to avoid eating animal by-products (glossary ID 41).

See a list of foods with genetically engineered ingredients that are in your local grocery store.

Explore More: Genetic Engineering
Copyright 2004, Iowa Public Television
The Explore More project is supported by funds from the
Roy J. Carver Charitable Trust
and the USDE Star Schools Program.