By tinkering with a single gene, researchers have weaned photosynthetic algae off their dependence on sunlight and engineered them to grow and thrive in darkness. This accomplishment, reported in the 15 June issue of the journal Science, could pave the way towards clean, efficient, and inexpensive production of microalgae, which are used in a variety of commercial applications.

Common microalgae products include fluorescent pigments used in scientific labeling, dietary supplements such as beta-carotene and the fatty acid DHA, which is essential for nervous system development in infants, and feed for farm-raised fish, shrimp, and other aquaculture products.

Since these single-celled aquatic plants depend on sunlight for their energy, they are typically commercially cultivated in large outdoor ponds. These pond "farms" have several drawbacks, however, that make it difficult to control the quality and quantity of their microalgae produce. Contaminants can invade the pond, daily and seasonal changes in light and temperature can make growth rates unpredictable, and the algae can shade each other after a certain point, restricting the available light.

To solve these problems, commercial producers would like to grow microalgae inside fermenters where the tiny plants could be monitored for maximum purity and productivity. This technique requires that the algae give up their photosynthetic ways and use glucose (or another carbon compound) as their primary energy source.

Since most microalgae are unable to make this switch on their own, the Science researchers gave the microalgae Phaeodactylum tricornutum a metabolic boost by introducing a gene that encodes a glucose transporter. The researchers experimented with a variety of glucose transporter genes from human red blood cells, a different microalgae species, and yeast to determine which transporter type might allow the algae to increase its rates of glucose uptake.

P. tricornutu
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Contact: Cherita Gonzales
cgonzale@aaas.org
202-326-6414
American Association for the Advancement of Science
14-Jun-2001