Seaweed farmer Nyafu Juma Uledi tends her crop in a tidal pool on Zanzibar Island in Tanzania, which exports thousands of tons of the greenery to Asia annually. (Photo: Finbarr O'Reilly/Reuters)

Genetically engineered microbe turns seaweed into biofuel

US-based scientists have successfully managed to engineer a microbe that reacts with seaweed to produce ethanol, and thus making it a new source of biofuel, an alternative to coal and oil. If the research can be applied at an economically feasible scale, it could finally set biofuels usage on an exponentially growth path, as seaweed doesn’t compete with food crops for arable land.

Most of today’s biofuels are extracted from crops like corn, sugar or oil palms, which are turned into ethanol. However, to reach today’s production mark of tens of billions of gallons worth of biofuel the industry had to use an immense amount of arable land, which directly interferes with actual food production and provides interest for companies to deforest rain forests and wood lands to make way for more crop land. Also, a entire arsenal of chemical fertilizers are used in the crop cultivation process. The last point has lead many climate experts to state that biofuels aren’t that green at all.

Since seaweed doesn’t compete with arable land, turning it into a biofuel energy source is an extremely interesting prospect, and scientists at Bio Architecture Lab, Inc., (BAL) have managed to accomplish just that. The Berkley, Ca. researchers used a genetically engineered form of E. coli bacteria that can digest the seaweed’s sugars into ethanol. They were inspired by the Vibrio splendidus bacteria, which brakes down alginate, the predominant sugar molecule in the brown seaweed. They then took the genetic machinery responsible for this process and split it into the E. coli. The scientists involved in the research claim that the engineered microbe gives 80% of the theoretical maximum yield, converting 28% of the dry weight of the seaweed into ethanol.

“Natural seaweed species grow very fast – 10 times faster than normal plants – and are full of sugars, but it has been very difficult to make ethanol by conventional fermentation,” said Yannick Lerat, scientific director at Centre d’Etude et de Valorisation des Algues. “So the new work is a really critical step. But scaling up processes using engineered microbes is not always easy. They also need to prove the economics work.”

Man has been harvesting seaweed for centuries as a food source. In China and Japan, there are farms that are the equivalent of the midwest cornfields in the US. It is believed that around 15 million metric tons of kombu and other seaweeds are grown and harvested as a food source. So the basis and mechanics for a biofuel centered farms is more or less already in place, but a lot of investment and work needs to be put in order to make seaweed produced biofuels economically feasible.

BAL currently has four aquafarming sites in Chile where it hopes to “scale up its microbe technology as the next step on the path to commercialization” in the next three years. A Carbon Trust official said seaweed biofuels are “still five times higher than they need to be to get to a reasonable fuel price” and that “the use of genetically modified microbes could be a concern in Europe – where the perception of negative impacts can be quite harmful – but less so in the US and elsewhere.”

Still, there’s a huge potential, considering most of the planet is covered in water. Also, the researchers claim that the microbe can used for making molecules other than ethanol, like plastics or sobutanol.

“Consider the microbe as the chassis with engineered functional modules,” or pathways to produce a specific molecule, synthetic biologist Yasuo Yoshikuni, a co-founder of BAL says. “If we integrate other pathways instead of the ethanol pathway, this microbe can be a platform for converting sugar into a variety of molecules.”


Leave a Reply

Your email address will not be published. Required fields are marked *