Engineering the Biofuel of the Future

NYU Abu Dhabi Associate Professor of Biology Kourosh Salehi-Ashtiani is placing his bets on common algae as a potential biofuel.

In the search for viable alternative energy sources, biofuels have been in the spotlight in recent years as strong candidates to lead the way for the future of clean energy. However, just as biofuels have been recognized for their potential, they have also been criticized for their limitations, including issues of scalability and for the significant land and agricultural resources they require that would otherwise be utilized in food production.

As research entities and ambitious start-up companies around the world join the race to discover practical techniques to harness usable energy from these sources — ranging from sugar- and starch-based crops like sugarcane and corn, to cellulose-based materials like wood and grasses — NYU Abu Dhabi Associate Professor of Biology Kourosh Salehi-Ashtiani is placing his bets on common algae. He is not alone. Algae have been noted for their oil production capacity, and according to the US Department of Energy, "can potentially produce 100 times more oil per acre than soybeans — or any other terrestrial oil-producing crop."

"Algae is an ideal system to probe fundamental aspects of biology, such as evolution, and genetic interaction, while working toward developing resources with very important practical use, such as biofuels, biopolymers, and nutraceuticals," Salehi-Ashtiani said.

Algal mass partially consists of lipids or triglycerides — the primary constituent in vegetable oils — which can be processed into transportation fuel that is suitable for use in existing machinery and systems. Once these oils have been harnessed, the remaining biomass can also potentially be used to generate fuels by other means, for instance through fermentation or pyrolysis. Algae can generally be found abundantly in various natural environments, do not consume human or animal food resources, and can thrive in salt and waste water, or on non-arable land. In addition, algae, like plants, are photosynthetic, taking in carbon dioxide and emitting oxygen as a byproduct. This means that algae not only produce clean energy with limited carbon emission and minimal impact on human agricultural resources, they can be used to clean up existing greenhouse gases in the environment. As this nascent industry matures, however, there are certain challenges that remain in the use of algae as a biofuel; namely cost efficiency and scalability of production.

This is why Salehi-Ashtiani's work in his Algal Systems Biology Lab at NYUAD on the genetic structure and engineering of Chlamydomonas reinhardtii, a model algal species, is particularly relevant. In the fall of 2011, he played an instrumental role in developing the first computational genome-scale metabolic model of an algal species, with predictive capacity on how gene manipulation can affect factors like growth and lipid production. The model also incorporates the impact of photosynthetic elements, including characteristics of varied light consumption and its impact on the metabolic process. The computational model can simplify the task of conducting an unfeasible number of bench lab experiments by providing predictions of the impact of altering a certain gene or set of genes. The genetic modeling of C. reinhardtii was a four-year collaborative project led by Salehi-Ashtiani and Jason Papin from the University of Virginia and was supported by 11 experts from a range of international institutions.

Salehi-Ashtiani, who has served as principal investigator on a number of projects funded by the US National Institutes of Health and the US Department of Energy prior to joining NYUAD, has since been continuing work with the model to run strain optimization experiments in Abu Dhabi. His research team is exploring the impact of altering certain factors in the genome to yield the desired results of higher lipid production and faster metabolic function.

Algae not only produce clean energy with limited carbon emission and minimal impact on human agricultural resources, they can be used to clean up existing greenhouse gases in the environment. As this nascent industry matures, however, there are certain challenges that remain in the use of algae as a biofuel.

Sonal Rupani

"Our approach is to look at metabolism at the systems level, which frequently means looking first at the genome. In collaboration with Michael Purugganan and his group at NYU New York, along with the NYUAD Center for Genomics and Systems Biology, we have now sequenced the genomes of approximately 20 or so C. reinhardtii strains, defining gene variations among these isolates. These strains, directly or indirectly come from various geographical locations. Using an array of photo-bioreactors, we aim to define metabolic characteristics of these strains — for example, growth rates and lipid contents — and to the extent that is possible, link them to their genomic variations. These strains are in a way optimization experiments that nature has carried out over many thousands of years and are now available to us to study. The information gained from our studies will clearly guide us to better design our future experiments."

Because C. reinhardtii has historically been used as a scientific model for understanding processes like photosynthesis, reproduction, and metabolism in microorganisms, genetic findings about this species are easily relatable to similar algal species. The NYUAD lab has begun exploring UAE- and region-based variations of algae, fitting them to the model to understand how different environments impact the characteristics of the organism. An environmental sampling program conducted in the extremely hot summer months in Abu Dhabi allowed the team to study organisms adapted to extreme climates. "This is rather important because any species or strain that would be useful for commercialization would need to be able to tolerate high environmental temperatures," Salehi-Ashtiani said.

Researchers at the lab are also using the model as a tool for continued discovery about the species and about the functioning of algal metabolism through testing specific hypotheses. For example, the species has both animal- and plant-specific genes. Through controlled wet bench and computational experiments, the research team is investigating how the genes within the metabolic network work together, hoping to answer a very basic question: Do genes tend to work with those that they have a similar evolutionary affinity with, or not?

"We have now carried out in-depth and integrated evolutionary and topological analyses on the metabolic network that we published in 2011. On the evolutionary side, we have interrogated more than 150 sequenced genomes to map evolutionary relationships of the 1,000 or so Chlamydomonas metabolic genes to (evolutionarily) near and far away lineages. On the topological side, we have defined pairwise relations, hubs, gene communities, and how the network behaves in response to light and dark," Salehi-Ashtiani said. "What's exciting is that we can see legacy of relationships in the network that may date back to hundreds of millions of years ago. With this information in hand, we are now at a much better position to understand metabolism of the algae and identify the key nodes within the network, and importantly, recognize key connections within the network."

As Abu Dhabi strives to diversify its economy and develop clean energy sources, Salehi-Ashtiani sees the emirate as an ideal location for this research. "I see Abu Dhabi as an environment that is very motivated in exploring new frontiers," he said. "I hope that we can start collaborative efforts with organizations here in the UAE to further this research. The potential and level of interest that I see here in developing renewable resources is going to be very important moving forward."

This article originally appeared in NYUAD's 2012 Research Report (12MB PDF)