What is in this article?:
- Biofuels jump forward with elimination of key cost barrier
- Power of genetics
Until now, harvesting fats from microbes has required many costly additional processing steps that contribute up to 80 percent of the total cost of their renewable biofuel production, making them uncompetitive compared with petroleum production costs.
Power of genetics
“Genetics is a very powerful tool,” added Liu, who recently presented the results at the 3rd Annual World Algae Summit in San Diego, Calif. “We have created a very flexible system that we can finely control. After teaching cyanobacteria to excrete fuels, we don’t want to waste the useful lipids in the photosynthetic membranes, so we developed a greener way to recycle the remaining value of the biofactory.”
The team tested fat-degrading enzymes, called lipases, from bacterial, fungal and guinea pig sources to see which would work best. These lipases are able work like molecular scissors, clipping off the fatty acids from the photosynthetic membranes. They also worked to optimize the growth conditions of their green recovery method, testing variables such as the cell culture density of the microbes, light intensity and agitation of the cultures.
The team’s ingenuity rests in part with their ability to utilize the full repertoire of nature’s toolkit. “Due to rapid DNA sequencing and public gene databases, we can now use this vast and ever-increasing store of gene sequences with powerful computer search methods to identify the best genes and proteins with optimal functions and capabilities independent of their origin in microbes, plants and animals,” said Curtiss. “It is like being a kid in a candy store the size of the State of Arizona and finding the most delicious candy treat almost in the time to snap your fingers!”
The project is also a prime example of the multidisciplinary, collaborative spirit of ASU research combining the expertise of bacteriologists, molecular biologists and engineers. Other key contributors were Biodesign colleagues Sarah Fallon and Jie Sheng.
Next, the group will test their results in large-scale photobioreactors, which are being designed by engineers in the institute’s Swette Center for Environmental Biotechnology to optimally capture the free fatty acids. Ultimately, the team hopes to achieve development of a new, economical and environmentally friendly, carbon neutral source of biofuels.
“We are optimistic that we can make the system even better, leading to the commercialization of our green recovery method bundled with other technologies,” said Liu.
The project has been part of the state of Arizona’s strategic research investments to spur new innovation that may help foster future green and local industries. The state’s abundant year-round sunshine and warm temperatures are ideally suited for growing cyanobacteria.
The work was supported by Biodesign Institute seed funding and a $5 million grant from the U.S. Department of Energy Advanced Research Projects Agency. The results were published in the early online edition of the Proceedings of the National Academy of Sciences.