Scientists engineered bacteria to produce bixin, a plant product used in many foods and cosmetics, after uncovering nature's genetic recipe for the pigment. Tomatoes capable of producing bixin, also known as annatto and used to add an orange touch to microwave popcorn and some cheeses, may arise from the advances reported in the 27 June issue of the journal, Science, published by AAAS, the science society.

This research may expand the supply of this economically important plant product used to add an orange touch to microwave popcorn and some cheeses, and texture and color to a variety of creams and cosmetics. Outside the laboratory, bixin is produced by a single, heavily-fruiting, small tropical tree, Bixa orellana.

First, the researchers figured out how the plant itself produces bixin. In addition to locating the three necessary genes, they demonstrated that lycopene is the physical precursor to bixin. Lycopene is the compound known to make tomatoes red.

Next, the authors moved to replicate this biosynthetic pathway in another organism.

"We chose to start with E. coli because you can insert all the genes at once. Tomatoes will be more complicated," explained senior author Bilal Camara from CNRS and Universit Louis Pasteur in Strasbourg, France.

Bixin genes are not the only genetic ingredient. The scientists added these genes to E. coli already engineered to produce lycopene. When the E. coli growing in test tubes began to produce bixin, they did not change color because the lycopene had already turned these single-celled bacteria red.

Lycopene is an antioxidant that gives foods such as tomatoes, watermelon and pink grapefruit their red color. It has made recent headlines as scientists investigate lycopene as a compound that may reduce the risk for some kinds of cancer.

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Contact: Daniel Kane
dkane@aaas.org
202-326-6634
American Association for the Advancement of Science
26-Jun-2003