[oil_from_algae] Grow in the dark algae…

this article is from 2001!

"Grow-In-The-Dark" Algae May Promise Dietary Supplements, Glowing=20
Pigments, And More, Say Science Authors
ScienceDaily (Jun. 15, 2001) =97 By tinkering with a single gene,=20
researchers have weaned photosynthetic algae off their dependence on=20
sunlight and engineered them to grow and thrive in darkness. This=20
accomplishment, reported in the 15 June issue of the journal=20
Science, could pave the way towards clean, efficient, and=20
inexpensive production of microalgae, which are used in a variety of=20
commercial applications.=20

Common microalgae products include fluorescent pigments used in=20
scientific labeling, dietary supplements such as beta-carotene and=20
the fatty acid DHA, which is essential for nervous system=20
development in infants, and feed for farm-raised fish, shrimp, and=20
other aquaculture products.=20

Since these single-celled aquatic plants depend on sunlight for=20
their energy, they are typically commercially cultivated in large=20
outdoor ponds. These pond "farms" have several drawbacks, however,=20
that make it difficult to control the quality and quantity of their=20
microalgae produce. Contaminants can invade the pond, daily and=20
seasonal changes in light and temperature can make growth rates=20
unpredictable, and the algae can shade each other after a certain=20
point, restricting the available light.=20

To solve these problems, commercial producers would like to grow=20
microalgae inside fermenters where the tiny plants could be=20
monitored for maximum purity and productivity. This technique=20
requires that the algae give up their photosynthetic ways and use=20
glucose (or another carbon compound) as their primary energy source.=20

Since most microalgae are unable to make this switch on their own,=20
the Science researchers gave the microalgae Phaeodactylum=20
tricornutum a metabolic boost by introducing a gene that encodes a=20
glucose transporter. The researchers experimented with a variety of=20
glucose transporter genes from human red blood cells, a different=20
microalgae species, and yeast to determine which transporter type=20
might allow the algae to increase its rates of glucose uptake.=20

P. tricornutum cells transformed with either the human or microalgal=20
glucose transporter gene increased their rates of glucose uptake=20
over normal cells, while the yeast genes produced no detectable=20
difference in glucose uptake. Unlike normal P. tricornutum, the=20
engineered algae expressing the human transporter were able to grow=20
in darkened fermenters at densities fifteen times that of sunlight-
grown algae.=20

Along with increased yield, the engineered algae grown in the=20
fermenters have another distinct advantage–protection from=20
microbial contamination. "Eliminating contamination means that the=20
algae can be produced at a high purity for pharmaceutical=20
applications or dietary supplements," says Science co-author Kirk=20
E.Apt of Martek Biosciences Corporation.=20

The Science authors say that their research "demonstrates that a=20
fundamental change in the metabolism of an organism can be=20
accomplished through the introduction of a single gene." They=20
acknowledge, however, that a one-gene solution will probably be the=20
exception and not the rule for future metabolic engineering=20
projects. In the case of P. tricornutum, for instance, the=20
researchers found that the complete cellular pathway for breaking=20
down glucose was "preinstalled" in the microalgae, and the=20
additional gene simply allowed the plant to take advantage of its=20
own systems.=20

In a related article in Science, Gregory Stephanopoulos of=20
Massachusetts Institute of Technology and Joanne Kelleher of George=20
Washington University School of Medicine suggest that metabolic=20
engineering is moving away from single gene modifications and=20
towards alteration of several targets within a particular=20
pathway. "My own suspicion is that it won’t always be this simple,"=20
says Apt. On the heels of their success with P. tricornutum,=20
however, the research team is already developing other commercially=20
important microalgae that can be grown using fermenter technology.=20

The other members of the research team include L.A. Zaslavskaia and=20
J.C. Lippmeier at Martek Biosciences Corporation, and C. Shih, D.=20
Ehrhardt, and A.R. Grossman at Carnegie Institute of Washington.=20
This research was supported in part by NSF and the Carnegie=20
Institute of Washington.=20

Adapted from materials provided by American Association For The=20
Advancement Of Science.

Need to cite this story in your essay, paper, or report? Use one of=20
the following formats:=20
APA

MLA American Association For The Advancement Of Science (2001, June=20
15). "Grow-In-The-Dark" Algae May Promise Dietary Supplements,=20
Glowing Pigments, And More, Say Science Authors. ScienceDaily.=20
Retrieved March 26, 2008, from=20
http://www.sciencedaily.com=AD /releas

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