Goat Milk Is Engineered to Contain Antibacterial Enzyme

Researchers at UC Davis have genetically engineered goats to produce an antibacterial milk that could eventually help protect children from diarrheal diseases, according to a report released today.

The goat milk was engineered to contain lysozyme, an important antibacterial enzyme in human breast milk that is substantially lacking in the milk of dairy animals.

“This is the first transgenic food product of any kind that has a potential health benefit specifically for the consumer,” said UC Davis geneticist James D. Murray, one of the study’s authors. “We have a huge opportunity to perhaps help human health.”

The researchers tested the milk in pigs, which have a digestive tract similar to humans’. In addition to their normal food and water each day, young pigs were fed about two glasses of pasteurized lysozyme milk.

After 16 days, the amount of coliform bacteria in the small intestines of pigs that received the lysozyme milk was significantly reduced compared with pigs given normal goat milk. In overabundance, the bacteria can cause gastrointestinal problems.

The report, published in the journal Transgenic Research, said the difference was similar to the difference found in studies comparing breast- and bottle-fed human infants’ intestinal bacteria: The breast-fed babies typically have less coliform bacteria and more “probiotic” bacteria, which are thought to help protect babies against diarrhea and other gastrointestinal illnesses.

Diarrheal diseases kill 2 million children each year worldwide, largely in developing countries. They are rarely fatal in the U.S.

Young goats that were fed the lysozyme milk had increased amounts of coliform bacteria in their intestines -- a result that surprised the researchers, who said goats’ different digestive systems might be an explanation. (Goats, like cows, have multiple stomachs.)

“Although the effects were different in the goats than in the pigs, the study demonstrates clearly that the consumption of pasteurized goat’s milk containing human lysozyme can impact the bacterial makeup of the digestive tract,” said food scientist Elizabeth Maga, a coauthor of the study.

Murray said the next step was to test whether the enzyme could retain its activity after the milk was powdered, to make it useful in international relief efforts.

Human studies are also needed, to test for allergic reactions or other problems.