Algae genes make hydrogen and ethanol

Scientists searching for the best hydrogen-producing bacteria to become a new energy source have sequenced the genome of one particularly promising type of blue-green algae. This organism performs two operations at once – it produces both hydrogen and ethanol, and one particular chromosome identified in it could turn out to be extremely important for producing biofuels. But to harness its hydrogen and ethanol-producing capabilities requires knowing lots more about this organism’s biology.

Blue-green algae, also known as cyanobacteria, are an important part of the marine nitrogen cycle. They transform gaseous nitrogen into forms of nitrogen usable by living organisms. Cyanobacteria are unique because they behave partially like plants and partially like microbes. That is, they perform photosynthesis just like plants, using the sun’s energy to produce sugar. And like bacteria, they process nitrogen.

This particular type of cyanobacteria has two cycles – during the day the cells perform photosynthesis, and during the night they switch gears to process nitrogen. They’ve found one key component, a linear chromosome, that the researchers believe is critical to the algae’s ability to perform this complicated switching maneuver. Linear chromosomes are extremely rare in bacteria, because usually they are almost exclusively found in more complex creatures, like plants and animals.

The research is supported by the Department of Energy, which has identified understanding blue-green algae biology as a Grand Challenge. The DoE wants to know which one of several different cyanobacteria produces the most hydrogen. Hydrogen is attractive as a replacement for fossil fuels because it burns cleanly and efficiently, it is renewable, and its production doesn’t have to release any carbon dioxide. These algae don’t just make hydrogen, though. Understanding the role that algae play at the ecosystem level in producing hydrogen, sequestering carbon, and manipulating marine ecosystems will shed much-needed light on how they interact with the atmosphere. This will also help explain how scaling them up to produce mass quantities of biofuels will affect the environment.

The main goal for now is finding the most efficient fuel-producing algae in nature, then potentially use the genetic data gleaned from that organism to engineer an even more intense variety, which might finally make them cost-competitive. That, of course, comes with its own set of environmental concerns, as Plenty contributer Emily Waltz writes this week. 

There are numerous kinds of algae, which is why some of them are known to be extremely toxic to humans, and sometimes they can blossom into harmful algal blooms. Other varieties are being considered by some marine biologists and the company Climos for their ability to sequester carbon dioxide and bury it in the sea.


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