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How are algae able to grow in the dark? Posted by Sumukhi on Mon August 30 2010 02:40:57 PM 60

Dark fermentation is in the news after 

Solazyme , an US based algae company delivered 1500 gallons of jet fuel to the US navy early July.

Interestingly, this company 's approach ( Earlier post) is different from the rest, they grow genetically engineered algae  in the dark and follow what is called the heterotrophic fermentation -  providing sugars for the algae, the sugars act as the carbon-source, the algae eat that up and accumulate lipids in their cells.

I was hence wondering how these algae strains which are known to grow only in the presence of light, photosynthetic  are  able to grow even when there is absolutely no light available. Though I realized that genetic engineering plays a role here, wanted to know more details about the genes which enable a photosynthetic organism to grow in the absence of light.

How and when did they isolate the  first algae strain that can grow in dark?

In 2001, researchers at the Department of Plant Biology of the Carnegie Institution of Washington in Palo Alto, California, and Martek Biosciences Corporation in Columbia, Maryland were the first to introduce a fundamental metabolic change in a single-celled alga so that it no longer required light to grow.

What did they do next?

The scientists first inserted one gene that catalyses glucose transport into the diatom Phaeodactylum tricornutum, (P. tricorntum is a oil-yielding algae which has about of 20% of oil in it)  The scientists then individually inserted several genes responsible for glucose transport from three different organisms into                  P. tricornutum.

The  genes  inserted were 1. hup1 gene - Chlorella kessleri  .2. Three other genes, hxt1, hxt2 and hxt4, come from the yeast Saccharomyces cerevisiae. 3. The final gene, glut1 from an unknown algae strain . Out of these genes, the hup1 and the glut1 showed great promise of enabling the organism to thrive in the dark!

To cut the long story short, it essentially means that the algae gets the energy exclusively from the glucose and those those two genes help the algae to consume the glucose and enables the organism to thrive in the dark!

See more -  http://www.greencarcongress.com/2008/02/solazyme-ups-so.html