The strains she engineered for FFA production show reduced photosynthetic yields, degradation of chlorophyll-a and changes in light-harvesting pigments, Ruffing said. She saw some cell death and lower growth rates overall, and suspects the toxicity of unsaturated FFA and changes in membrane composition are responsible.
Now she's looking at what genes are changing when cyanobacteria produce fatty acids. She's creating mutants by knocking out certain genes or introducing or overexpressing genes to see how that affects the cell and fatty acid production.
"So I'm engineering the cell, then I'm trying to learn from the cell how to work with the cell to produce the fuel instead of trying to force it to produce something it doesn't want to produce," she said.
She's producing FFA from Synechococcus elongatus PCC 7942 and Synechococcus sp. PCC 7002, chosen as so-called model organisms that have been studied for several decades and for which tools exist to manipulate their genes. She also is working with the two strains and a third, Synechocystis sp. PCC 6803, for biofuel toxicity screening.
Ruffing hopes to continue working on strain development after the fellowship ends.
"It is possible that there's a natural strain out there that could be a better option, so this is still pretty early research," she said. "There's a lot of exploration to do."
|Contact: Sue Holmes|
DOE/Sandia National Laboratories