But current yields from engineered strains are too low for large-scale production.
Ruffing favors cyanobacteria because fuel from engineered cyanobacteria is excreted outside the cell, in contrast to eukaryotic algae, in which fuel production occurs inside the cell.
In general, this is how the process works: Eukaryotic algae grow in a pond to the density needed, then producers must get rid of the water, collect the cells and break them open to get the fuel precursor inside. This precursor is isolated and purified, then chemically converted into biodiesel. Cyanobacteria excrete the fuel precursor outside the cell, so a separation process can remove the product without killing the cells. That eliminates the need to grow a new batch of algae each time, saving on nitrogen and phosphate.
While other research efforts have focused on metabolic engineering strategies to boost production, Ruffing wants to identify what physiological effects limit cell growth and FFA synthesis.
"You can't really hope to continue to engineer it to produce more of the fatty acids until you address these unforeseen effects," she said. "As much as you want to do the applied side of things, creating the strain, you can't get away from the fundamental biology that's necessary in order to do that."
Much of our fundamental understanding of photosynthesis comes from cyanobacteria, but it's only been in the past decade or so, with advances in gene manipulation and recombinant DNA technology, that they've been considered for fuel production, Ruffing said.
|Contact: Sue Holmes|
DOE/Sandia National Laboratories