On This Page:

Summary: GE bacteria, fungi, and yeast in food production.
GE enzymes from bacteria and fungi.
GE yeast in beer and bread.

The techniques of genetic engineering have been applied to food production for nearly a decade before genetically engineered plants first arrived in US markets in 1994. Genetically engineered bacteria and fungi are routinely used as sources of enzymes for the manufacture of a wide variety of processed foods. In a few cases, genetically engineered yeast has also been approved for food uses, but these are not yet being used in food production.
[top of page]

Several strains of bacteria and fungi have been genetically engineered to produce enzymes important in food production. These organisms are grown in vats to produce large quantities of the enzymes, and then the enzymes are extracted, purified, and sold to food processors, who use the enzymes in food production. Living bacteria and fungi are not actually added to food products, only the enzymes that are extracted from them. In most cases, the enzymes are no longer present in the finished food product-- destroyed or removed by further cooking and processing-- and for this reason they are rarely listed in the food label ingredient list.

Many of the enzymes used in food production were originally taken from non-GE bacteria and fungi, but new strains of these organisms have been genetically engineered to add a number of improvements:

• make larger quantities of the enzyme
• create a cheaper, more reliable source of the enzyme
• improve the purity of the enzyme
• improve the enzyme's function in its processing use

Chymosin is an enzyme that is important to the production of hard cheeses-- the enzyme is necessary to clot milk proteins to form cheese and whey. Until recently, most chymosin had to be extracted from the stomach linings of calves (an extract called "rennet"). In 1990, chymosin produced by genetically engineered bacteria was first approved in the US, and now more than 70% of US cheeses are manufactured with this enzyme.

The following table lists the most common food-processing enzymes extracted from genetically engineered bacteria and fungi, with examples of their uses:

Enzyme Name	GE Organism	Use (examples)
alpha-acetolactate decarboxylase	bacteria	removes bitter substances from beer
alpha-amylase	bacteria	converts starch to simple sugars
catalase	fungi	reduces food deterioration, particularly egg-based products
chymosin	bacteria or fungi	clots milk protein to make cheese
cyclodextrin-glucosyl transferase	bacteria	starch/sugar modification
beta-glucanase	bacteria	improves beer filtration
glucose isomerase	bacteria	converts glucose sugar to fructose sugar
glucose oxidase	fungi	reduces food deterioration, particularly egg-based products
lipase	fungi	oil and fat modification
maltogenic amylase	bacteria	slows staling of breads
pectinesterase	fungi	improves fruit juice clarity
protease	bacteria	improves bread dough structure
pullulanase	bacteria	converts starch to simple sugars
xylanase (hemicellulase)	bacteria or fungi	enhances rising of bread dough

[top of page]

Yeast is used in the production of baked, "leavened" breads and in brewing beer. In this case-- unlike the use of enzymes in food production-- live yeast is added directly to the food product. Although genetically engineered yeasts have been developed for use both in bread-making (faster-rising) and in beer brewing (lower sugars for "lite beers"), they are not currently being used by US processors.
[top of page]