Green slime starts to shine
Martin Spalding
Natural photosynthetic systems that use solar energy to capture carbon are ripe for engineering innovation. One group holding promise for generating renewable biofuels and chemicals are microalgae, organisms Martin Spalding, professor and chair of the Department of Genetics, Development and Cell Biology has been studying for over 30 years.
Primarily focused on the model microalga, Chlamydomonas reinhardtii, Spalding is working to overcome metabolic obstacles to encourage natural oil production in these single-celled photosynthetic organisms.
"Chlamydomonas reinhardtii is the only microalga with a robust genetic engineering base, and the only microalga we can easily manipulate genetically to combine traits," explains Spalding. "It is highly malleable and we can transform all three of its genomes—nuclear, chloroplast and mitochondrial."
The organism stores its carbon as oil more readily when deprived of certain nutrients but preferentially stores excess carbon in the form of starch. Starch is its energy source during dark periods. But when microalgae are grown in constant light, Spalding explains, they don't need starch to live.
So Spalding and colleagues Larry Halverson, assistant professor in the Department of Plant Pathology and Basil Nikolau, Francis M. Craig Professor in the Department of Biophysics, Biochemistry and Molecular Biology selected a starchless mutant for study —one that cannot store carbon in starch because it lacks a necessary enzyme.
They will compare the essential genes and metabolites of this mutant to the wild type, setting their sights upon identifying vital modifications in this metabolic pathway that will optimize oil production. As this mutant is also only a moderate oil producer, detecting even small increments in oil production advances should be straightforward.
Additionally the team will introduce prospected genes from other organisms into the mutant, such as plants or other microalgae, whose biochemical products might shepherd carbon through the lipid biosynthetic pathway.
"We will be pushing from the beginning of the pathway and pulling from the end to improve the amount of oil produced," says Spalding.
Initial support for this project is being provided by the institute's Innovative Grants Program.
