Technology Behind the Green Fuel of the Future

Scientists at Scripps Institution of Oceanography at UC San Diego are deciphering the energy mechanisms inside tiny marine algae to determine their potential as the most promising biofuel source on the planet.

A National Science Foundation (NSF) research award to Scripps biologist Mark Hildebrand through the American Recovery and Reinvestment Act (ARRA) aims to unlock the bioenergy secrets of algae known as diatoms and find ways to maximize their production of fatty oils, or “lipids,” that can be developed to power everything from automobiles to jets.

Hildebrand is probing a catch-22 in algal biofuel research. Algae produce lipid oils when they are starved for nutrients. Yet if they are limited in nutrients, they don’t grow well. Give them a healthy diet to grow and they produce carbohydrates instead of desired lipids. Hildebrand and his laboratory team are investigating how genes turn on and off, or how they are “expressed,” in lipid production.

“If we can grow cells under conditions where they are not making lipids and another batch where they are, we can compare changes in gene expression patterns and that will help us identify the genes that are induced when lipids are produced,” said Hildebrand.

With $300,000 in NSF-ARRA funding, Hildebrand is engineering methods to disrupt the transportation of silicon inside diatoms. This action induces artificial starvation, and thereby produces lipids. Similarly repressing cells for nitrogen also could yield lipids in other algal species.

Artificial starvation techniques could be vital in outdoor ponds where algae are currently grown and developed for biofuel research, but subject to contamination by various airborne threats.

“If this idea works then you wouldn’t have to rely on highly variable environmental conditions. You could dictate when you want to have that (lipid production) response happen,” said Hildebrand.

Aiding this research is Scripps’ recent acquisition, through NSF-ARRA funds, of two sophisticated flow cytometers, instruments capable of detecting fine aspects about large numbers of cells. Hildebrand, Scripps co-principal investigator Brian Palenik, and others will use these instruments to characterize and isolate cells with desired lipid accumulation or growth traits from a bulk population, offering a new approach to the development of algal biofuels technology.

Complementing the two flow cytometers is a “multisizer” instrument that provides highly accurate and sensitive measurements of the volume of cells.

Beyond biofuel research, the new suite of three high-precision instruments is giving Scripps researchers new capabilities in topics ranging from ocean microbes to genome sequences to biotechnological applications. High school and college undergraduate students also will have access to training and utilization of the modern tools.

In addition to Hildebrand and Palenik, researchers at Scripps and UCSD involved with the new instrumentation include Eric Allen, Farooq Azam, Bianca Brahamsha, Bill Gerwick, Lena Gerwick, Susan Golden, Jim Golden, Steve Kay, Mike Landry, Michael Latz, Greg Mitchell, and Maria Vernet.

— Mario C. Aguilera