Fuel from Seaweed

I grew up on the coast of California, and I loved to surf. At my favorite break, Pleasure Point, the best waves were often at low tide, but low tide also meant seaweed. Lots of seaweed.

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The giant kelp of Monteray Bay is an astonishing organism. It’s not actually a plant, it’s a brown algae, and it can grow 12 inches per day. This rapid growth makes it an ideal resource, and a bane of surfers that get their fins caught in thick mats.

You can’t tell, but it was definitely kelp that made me fall, not the fact that I was too far forward and unable to turn. No, really…

Brown algae like kelp can be harvested as a source of algin, and other types of seaweed are also used as sources for products like agar that we use in labs to make bacterial culture plates.

But there’s also been a lot of interest in using different sorts of algae as feedstocks for the production of biofuels. Their rapid growth makes them eminently renewable, they require almost no effort to cultivate, no fertilizer, no fresh water, they would not use up arable land that can be used for food crops. The main draw back is that one of the most abundant sugars present in algae, called alginate, is not digestible by the microorganims currently used for biofuel production at an industrial scale. Until now.

ResearchBlogging.org



It turns out there are a number of microbes that have been shown to digest alginate. Other groups have engineered those organisms to be able to produce ethanol, but those bugs aren’t super robust when grown under lab conditions, and it’s harder to genetically manipulate bacteria that you don’t have a lot of experience with. Adam J. Wargacki and his colleagues took the opposite approach – instead of getting the genes for making ethanol into a relatively unknown microbe that can digest alginate, why not grab the genes for digesting alginate and stick them in E. coli? Scientists have been picking this bug’s locks for decades, and it’s already been engineered to make not just ethanol, but many other useful products as well.

And that’s exactly what they did. Only it’s a bit more complicated than I’ve let on here. It’s not a single enzyme that’s necessary to break down alginate into something that can be turned into ethanol by E. coli. Alginate is naturally found in long chains of repeating sugars – a polymer – which means you can’t really get it inside bacterial cells, so the first step is to get the bacterium to make an enzyme that cuts up the polymer into smaller pieces. However, just making this enzyme isn’t enough, you need the bug to pump that enzyme out into the extracellular space.

So Wargacki et. al. selected an alginate lyase (an enzyme that can bust up those long polymers) that had been previously described, and modified it to be recognized and secreted by a simple E. coli transporter. When they expressed both this modified enzyme and the transporter, they detected rapid production and secretion of the enzyme, and it was incredibly active. But they weren’t done yet.

The long polymer of alginate could now be broken up, but the small pieces would still need to get into the bacterial cell, and then converted into a type of sugar than E. coli can use to make ethanol. So Wargacki and friends turned to another organism known to be able to import and digest alginate – Vibrio splendidus (splendid!) – and managed to pull out of its genome a series of enzymes used for exactly those purposes and clone these genes into an expression vector usable in E. coli. Writing it up like this makes it seem easy, but in what I described in this paragraph is an unbelievable amount of work.

The last figure shows the end result. They cultured their newly engineered E. coli, complete with enzymes, exporters and importers, with brown algae, and checked on the concentration of various products at different time points. Alginate is in green, and ethanol is in blue.

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They ended up getting 4.7% alcohol by volume, which pretty close to the benchmark for biofuel production from cellulosic feedstocks like corn. It’s also similar to the a.b.v. of many beers, though I’m not sure I’m ready for a seaweed brew just yet. Maybe after a long day of surfing…

Wargacki, A., Leonard, E., Win, M., Regitsky, D., Santos, C., Kim, P., Cooper, S., Raisner, R., Herman, A., Sivitz, A., Lakshmanaswamy, A., Kashiyama, Y., Baker, D., & Yoshikuni, Y. (2012). An Engineered Microbial Platform for Direct Biofuel Production from Brown Macroalgae Science, 335 (6066), 308-313 DOI: 10.1126/science.1214547

Comments

  1. #1 David Marjanović
    January 26, 2012

    Awesome!

    One alga, two algae. Regular Latin.

  2. #2 Justicar
    January 26, 2012

    I hate leaving pissant, vacuous comments of the ‘cool story, bro’ species, but my knowledge of this field is so scant that I can say little more. But I wanted to leave feedback so you know your writings are being read by people who find your reduction to outsiders of the field useful and informative. And like totally not boring.

  3. #3 Kevin
    January 26, 2012

    @ David – So, “It’s a brown alga,” but “Brown algae like kelp?” I feel like this is a situation where the word has been appropriated in English to where algae is usable in both situations. Kind of like media (especially as it’s used in labs).

    @ Justicar – I’m fine with “cool story, bro,” as I actually talk like that occasionally. Gnarly and bodacious are also acceptable, though bodacious in particular is a bit dated.

  4. #4 frank habets
    January 26, 2012

    It’s the bee’s knees!

  5. #5 Linder
    January 26, 2012

    excuse me but ethanol is NOT a useful product. It is quite effective in damaging small engines. The only reason we have ethanol is becuase certain politicians decided to do some insider trading and bought stocks in corn and then madated everyone put corn in their gasoline and made millions from their own laws.

    Ethanol needs to be banned from use in gasoline. It hinders horsepower, corrodes engines and damages engines, and attracts water. Newflash to science. the combustion engine cannot run on 10% water. It doesn;t work that way.

    We have enough oil on this planet to power everything in existance for all eternity. Use it. it works. it is proven.

    If you wish to use something else, how about making your scientific minds useful and use hydrogen. Electric cars suck. The range is short, so no more cross country trips. The batteries are expensive to replace. They do not work well in cold climates. They are as ugly as the liberals who worship them.

    Besides we could use the corn for another purpose. say, like FOOD! It goes well with fetus pepsi.

  6. #6 Linder
    January 26, 2012

    Leave to california to come up with some shit like this. People of california need to live in Mississippi for at one year and see thee real world. Your marxist utopia hinders you from thinking correctly. That and the flouride water and the aluminum based vaccines.

  7. #7 Justicar
    January 27, 2012

    How about Gnarles and Barkley to make it modern?

  8. #8 Justicar
    January 27, 2012

    Oh, Linder – you do amuse.

    We have enough oil on this planet to power everything in existance for all eternity. Use it. it works. it is proven.

    Sweet! People from the future have spoken! And in a blind taste test, they prefer the choice of a New Generation.

  9. #9 Kevin
    January 27, 2012

    @ Linder – All I could think while reading your comments were “Poe’s Law! Poe’s Law!”

    @ Justicar – I haven’t listened to that song “crazy” in ages… thanks for reminding me.

  10. #10 Linder
    January 27, 2012

    Edgar Allen Poe? I did not realize he was in the legislature, but carry on.

    You run your little electric toy cars and your ugly annoying windmills and your solar crap. I’ll stick with what works best for my individual sitution. At least until the ethanol locks up my engine. Nice to know we have dumbasses and criminals running the world. It will be even nicer when judgement day comes and I get to push a few of them in the fire.

  11. #11 Jerry Atric
    January 27, 2012

    Linder may be a poe, but I want some moe. Keep it coming.

  12. #12 Douglas Watts
    January 27, 2012

    Seaweed is already the most efficient use of seaweed. This is like saying wood chips are the most efficient use of 500 foot redwood trees.

  13. #13 sedeer
    January 28, 2012

    I haven’t really been following what’s going on with bioenergy, but it’s great to read about this sort of development. I do think we need to start trying to incorporate alternative resources like algae and insects into our food and energy systems. Out of curiosity, do you know why they chose to try to solve this problem by engineering rather than evolving the ability to digest alginate?

    I’ve always heard ‘alga’ used as the singular and ‘algae’ as the plural. In fact, medium/media is also used in my lab; we talk about growing plants on a medium with XXXX or on several different media.

  14. #14 harold
    January 28, 2012

    The comments by Linder are biased, but do touch on some valid issues.

    excuse me but ethanol is NOT a useful product.

    Yes it is, for many, many applications.

    Fuel ethanol from plants or algae is not perfect, but is a liquid transportation fuel that has a number of advantages over fossil fuels. Fuel ethanol is potentially a good part of an overall strategy of shifting to sustainable and renewable energy sources. Because the carbon released when ethanol is oxidized is merely carbon that was recently fixed from the atmosphere by the plant or algae crop used to make the ethanol, oxidization of ethanol (not necessarily its production or transport) is essentially carbon neutral.

    Using perverse subsidies to motivate the production of fuel ethanol from food corn is, I agree, a terrible idea, but making fuel ethanol from non-food products, or even the much cheaper and less nutritious food product cane sugar, is potentially a good idea. Fortunately, this piece describes efforts to use seaweed, not corn, to produce fuel ethanol.

    It is quite effective in damaging small engines.

    Ethanol is not very corrosive, but it is more corrosive than fossil fuels, largely because it is so much more hydrophilic. Certainly it is best to use fuel ethanol in a vehicle which was designed for it http://en.wikipedia.org/wiki/Alcohol_fuel

    This isn’t a big issue for modern engines, contrary to the claim here, and in fact, even the Model T Ford could burn either ethanol or gasoline without any modification.

    Ethanol can’t be transported in standard pipelines. It is valid to note that as a limitation of ethanol. However, fuel ethanol is still potentially valuable.

    (Incidentally, biodiesel is not as corrosive).

    The only reason we have ethanol is becuase certain politicians decided to do some insider trading and bought stocks in corn and then madated everyone put corn in their gasoline and made millions from their own laws.

    While this is exaggerated and sounds paranoid, I agree with the general idea that subsidizing the production of fuel ethanol from food corn is a terrible idea. Fortunately, this piece describes efforts to use seaweed, not corn, to produce fuel ethanol.

    Ethanol needs to be banned from use in gasoline.

    Linder is making a common error here. Ethanol is currently added to all gasoline, in relatively small amounts, as an anti-knock agent. The is because tetra-ethyl lead was banned, due to its tendency to seep into ground water. I realize it is confusing that ethanol can be either a primary fuel, or, in small quantities, an anti-knock agent in gasoline, but those who wish to know what they are talking about should try to grasp this distinction. Use of ethanol as an anti-knock agent has been going on for many years and there is no evidence whatsoever that it does significant damage to engines.

    It hinders horsepower, corrodes engines and damages engines, and attracts water. Newflash to science. the combustion engine cannot run on 10% water. It doesn;t work that way.

    This statement makes no sense; ethanol isn’t water, and vehicles have already been running perfectly well on ethanol for decades.

    We have enough oil on this planet to power everything in existance for all eternity. Use it. it works. it is proven.

    1) No we don’t.

    2) Even if we did, there are still many other arguments against heavy use of fossil fuels.

    If you wish to use something else, how about making your scientific minds useful and use hydrogen.

    There is nothing wrong with studying hydrogen fuel. (It’s odd that wingnuts with an obsessive oil fetish don’t object to hydrogen fuel; I guess that since George W. Bush touted the idea they feel comfortable parroting this.)

    However, ethanol can easily be used in standard internal combustion engine vehicles right now, and often is.

    Electric cars suck. The range is short, so no more cross country trips. The batteries are expensive to replace. They do not work well in cold climates. They are as ugly as the liberals who worship them.

    Nobody “worships” electric cars. As for the rest of this, it’s all partly true, but it’s all just a description of the limitations of today’s early electric cars. All of this was equally true of early gasoline cars.

    Also, of course, fuel ethanol has nothing to do with electric cars, although it could be used as a liquid fuel reserve in a partly electric car (as could and is gasoline).

    Besides we could use the corn for another purpose. say, like FOOD!

    I do agree that using food corn for ethanol is stupid. Fortunately, this piece describes efforts to use seaweed, not corn, to produce fuel ethanol.

    It goes well with fetus pepsi.

    I suppose this incomprehensible statement is intended to be obnoxious, possibly in an effort by Linder to portray himself as a “rebel” or “maverick”.

    [This comment got caught in the spam filter and I didn't see it until 2/1/2012 - Sorry about that. Thanks for taking the time to go through Linder's post as if you took it seriously, this is all great info for people that might come to this thread later. - KB]

  15. #15 Elizabeth Munroz
    January 29, 2012

    Ah… Pleasure Point! I knew I’d seen you before! Aw, c’mon, Linder… DUDE!!! Give us crazy Californian’s a break, man. Imagine how tubular those waves would be without all that chokey green stuff! You know what they say, “When god made America, he turned it on end, gave it a shake and that’s where all the fruits and nuts landed.” Even god made that algae stuff for sumpin’ besides trapping surfers. Ya know what I mean, bro’? Where’s the love? Peace out!

  16. #16 Justicar
    January 29, 2012

    This is like saying wood chips are the most efficient use of 500 foot redwood trees.

    Are you trying to imply that organisms with metabolism are more efficient than chopped up ones without metabolism?

  17. #17 Kevin
    January 29, 2012

    @ Linder – Surely you know how to google. Your feigned ignorance is pushing me further towards the my troll suspicion.

    @ Jerry – Don’t feed the… eh, nevermind, I laughed.

    @ Douglas –

    like saying wood chips are the most efficient use of 500 foot redwood trees

    Who said anything about efficiency? Humans want energy, and this is a more sustainable way of getting it. I’m not quite sure what you’re objecting to.

    @ Elizabeth – Righteous, dude.

  18. #18 NJ
    January 29, 2012

    The commenter using the ‘nyms “Linder” and “Jerry Atric” is almost certainly one Rob Hood, who has haunted Orac’s and Greg Laden’s blogs for quite some time under a variety of names; the references to “flouride”, aluminum in vaccines and Marxism are pretty convincing tells. If prodded, he will launch into tirades about Canadians, how the HAARP project caused the Japanese earthquake/tsunami, how people who understand climate change need to be arrested, and most recently, about aborted fetus cells in Pepsi products.

    Rob Hood is not so much a troll as a person with an horrifically undertreated mental illness. A quick search of SB on his name or some of his ‘nyms (Dr. IM Smart, Medicien Man (sic)) can demonstrate this.

  19. #19 Kevin
    January 29, 2012

    @ NJ – Your knowledge of the fringe elements among Sb commenters is impressive and informative, thanks. I pity poor Orac and Greg, considering that their readers can recognize the crazy from their blogs, I can only imagine what they’ve been dealing with behind the scenes.

    On the other hand, if I’m his new Target, maybe I won’t have to imagine for long.

  20. #20 Paul
    January 31, 2012

    Or, polysaccharides could be processed by thermochemical techniques and hydrogenated to biogasoline, using technology like that from Virent. No need for fussy sensitive enzymes, and the result is a drop-in replacement for current vehicle fuel.

  21. #21 Kevin
    January 31, 2012

    @ Paul – I’m all for multiple approaches, and I think making synthetic hydrocarbons from renewable sources that can fit into our current infrastructure is an awesome bridge. However, I don’t think Virent’s techniques could utilize algal polysaccharides effectively at this stage, and using cellulosic material still requires pretty energy-intensive techniques to liberate all the sugars for further processing, reducing efficiency.

    All of these techniques can go together and complement each other though. Imagine using algal-produced ethanol to drive the processes that liberate cellulosic sugars that are converted into carbon-neutral gasoline. Ultimately, I think having a plethora of potential sources of energy will make the end of fossil fuels come more rapidly and with less disruption.

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