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How are algae able to grow in the dark? 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

Mon August 30 2010 02:40:57 PM by Sumukhi algae  |  genetic engineering 10224 views

Comments - 9

  • Erika wrote:
    Mon August 30 2010 03:50:19 PM

    I am interested in hydrolysis of cellulose/lignocellulose for use in dark fermentation algae production. Does anyone have any information regarding? Interested in addressing BOD remediation at a chlorine-free pulp mill using algae. Thank you!

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  • Shankar wrote:
    Mon August 30 2010 10:21:38 PM

    @ Sumukhi

    Thanks for demystifying Solazyme's process.
    I have been keen on knowing what makes the difference and how they made it.

    I am still keen on knowing how they are able to achieve economic viability in terms of price. I guess it must be because of the co products.
    But how will they be able to scale up.
    From what i learn, they use vats in which they put sugar and hungry gene modified algae, which eat up the sugar and form lipids. Isnt it a batch process ?
    Can a batch process scale to reach pump quantity ?

    Anyway I must thank you for the insightful article , as it explained to me what appeared a great mystery.
    Especially because they went against the run of th e game. ie away from photosynthesis.

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  • Natalia wrote:
    Mon August 30 2010 10:34:30 PM

    Do they feed refined sugar or plant sugars like baggase, in which case it can be economical.

    Shankar's question of scale, remains though !

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  • Natalia wrote:
    Mon August 30 2010 10:35:05 PM

    @ Erika

    What is BOD ?

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  • Sumukhi wrote:
    Tue August 31 2010 02:57:10 AM


    Thanks for your comment!

    Oh yes,Harrison Dillon- the CTO of Solazyme even said that they are not only looking at biofuels, they are also looking at high-value end products such chemicals ,nutritionals (Human Animal Nutrition), cosmetics as well as nutraceuticals.

    They claim that their process is economically viable as they use waste industrial biomass and other waste cellulosic biomass from which the sugar is obtained.. But as you rightly pointed out,their process is economically viable because they are also looking at the co-products.

    Yes, it is a batch process and as the fermenter exhibits a controlled environment i.e there is no water loss, temperature fluctuation etc.. and if the biomass is being harvested at least every ten days, I think batch cultivation will be the most viable option!

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  • Sumukhi wrote:
    Tue August 31 2010 03:00:23 AM


    BOD is Biological Oxygen Demand -Biological Oxygen Demand (BOD) is the amount of oxygen used by microorganisms to decompose rather remediate the organic matter present in the waste water.

    If there is a large quantity of organic waste in the water supply, there will also be a lot of bacteria present working to decompose this waste.

    In this case, the demand for oxygen will be high (due to all the bacteria) so the BOD level will be high. As the waste is consumed or dispersed through the water, BOD levels will begin to decline.


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  • Arden wrote:
    Tue August 31 2010 03:28:18 AM

    @ Erika

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  • Lucygreen wrote:
    Tue August 31 2010 02:59:08 PM


    Check out this paper .. Provides a lot of useful insights on the hydrolysis of lignocellulosic biomass for carrying out dark fermentation. This paper is however for biohydrogen production.Am not sure what product you are looking at?

    http://nopr.niscair.res.in/bitstream/123456789/2424/1/JSIR 67(11) 962-979.pdf

    Hope this helps!

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  • Erika wrote:
    Tue August 31 2010 03:22:14 PM

    @ Sumukhi

    Thank you for clarifying BOD

    @ Arden &
    @ Lucygreen

    Thank you for the leads

    Regarding pulp mill effluent: The mill is required to build a new wastewater treatment system within ~3 years time. Current plans are for an activated sludge system (high cost to build/maintain). The mill is the only totally chlorine free mill in the USA, presenting a unique opportunity to explore an alternative wastewater treatment system which may yield a harvestable product. Initial growth tests show that algae are able to grow in the effluent with only mild pH balancing. I am curious if any of you have any creative ideas how to address the organic particulates (cellulose/lignocellulose).

    Thank you all!

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