American Scientists Engineer Oil-Oozing Algae in Bid to Speed Biofuel Production
By Scott Doggett March 30, 2010
A research team has developed a microbe that secretes oil, potentially eliminating a major step for biofuel production.
Xinyao Liu and Roy Curtiss of Arizona State University's Biodesign Institute have genetically engineered cyanobacteria to ooze fatty acids that can be used to make vehicle fuels, according to a paper published in the Proceedings of the National Academy of Sciences.
Most approaches to making fuel from algae involve growing organisms that store oil inside their cell walls. When they have matured, the algae are harvested and pressed to collect the oil for further processing.
But Liu and his colleagues say they have tweaked a strain of microbes to push the oil out through the exterior membrane, simplifying the harvesting process and allowing the oil to be collected without killing the microbe.
"In China we have a saying ... we don't kill the hen to get the eggs," Liu said in a description of the work. "I use genes that can steal fatty acids from the lipid synthesis pathway" using a protein called theioesterase.
The team also genetically modified the cell walls to let fatty acids pass through them more easily. Another change caused the microbes to over-produce fatty acids.
Cyanobacteria, the microbe that Liu's team uses, is appealing for making biofuels because it can be grown in liquid containers, without relying on land that could otherwise be used for food or other purposes.
"The seminal advance has been to combine a number of genetic modifications and enzyme activities, previously described in other bacteria and in plants, in the engineered cyanobacteria strains along with the introduction of newly discovered modifications to increase production and secretion of fatty acids," said Curtiss, who directs the Biodesign Institute's Center for Infectious Diseases and Vaccinology.
Curtiss said he is confident the team will be able to further develop the research "to achieve enhanced productivity in strains currently under construction and development."
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