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Yeast adds vitamins to bread

Bread loaded with beta-carotene, the stuff that makes carrots orange and helps prevent blindness, could improve the health of millions of people, thanks to a strain of genetically enhanced yeast developed by undergraduate students.

"It looks exactly like normal bread," Arjun Khakhar, a junior biomedical engineering student at Johns Hopkins University, told me Monday. "There's no orange color or anything because the yeast only makes up a very small part of the bread."

Due to government regulations that prohibit human consumption of non-approved genetically modified foods, Khakhar noted that he and his team haven't actually tasted the bread. 

iGEM competition

The VitaYeast, as the strain is called, is one of 60 projects that have advanced to final round of the 2011 International Genetically Engineered Machine competition scheduled for Nov. 5-7 at the Massachusetts Institute of Technology.

The competition draws students from around the world who are engaged in the emerging field of synthetic biology where bits of DNA and other biological material are manipulated to create systems that carry out new tasks.

The yeast, for example, includes a piece of beta-carotene producing DNA that was synthesized by the Johns Hopkins University team and integrated with genes in a cell of baker's yeast.

The modified yeast strain does what yeast has done for bread for thousands of years — make it rise — but it also triggers a series of biochemical reactions that produces beta-carotene. When eaten, beta-carotene turns into vitamin A.

Khakhar and his team tout it is a relatively simple way to help hundreds of thousands of people who are suffering from malnutrition due to inadequate access to fruits and vegetables.

"People in developing countries can just eat the bread and get their daily requirement of vitamin A," he said.

Genetic parts list

Teams that register for the competition are provided with a kit of standard genetic parts that can be mixed and matched — and they are encouraged to design their own parts as well —  as they build biological systems and operate them in living cells.

The program began in 2003 with a month-long course at MIT where students designed systems to make cells blink. The course grew to a competition in 2004 and has since opened up to international groups and grown rapidly in the ensuing years. 

Last year, 130 teams competed with projects ranging from an arsenic biosensor to banana and wintergreen smelling bacteria. This year, 160 teams from 30 countries entered the competition. Among the other finalists are:

Finding a market

Whether any of these projects will become a marketplace success is unknown, but the field of synthetic biology is flush with innovation and these students are learning the skills necessary to be market leaders, according to MIT's Technology Review.

Khakhar is well aware that gaining acceptance of genetically modified organisms is difficult, whether or not his team wins the competition. His team has already put together a survey to help gauge public opinion about bread baked with modified yeast.

"We want people to accept it," he said, noting the failure a few years ago in Africa of golden rice, which is strain of rice engineered to produce beta-carotene. "It is useless to develop something if nobody uses it."

That's actually one of the reasons he and his team settled on making bread with their yeast and not beer, where yeast also plays a crucial role.

Key to the decision to focus on bread are plans to engineer VitaYeast to produce other nutrients such as vitamin C and folic acid.

"Folic acid is important for pregnant women and you don't want to be asking pregnant women to drink a beer," Khakar noted. "But it can absolutely be used for beer as well."

More on genetic manipulation:

More from the Future of Technology series:

John Roach is a contributing writer for To learn more about him, check out his website.