Monday, May 10, 2010

Gene-Engineering the Best of all Possible Algae


Iowa State University scientists are hard at work engineering the best genetic strain of algae for the production of biofuels.
“It’s a great time to be a scientist,” says Eve Wurtele, professor of genetics, development and cell biology at Iowa State University in Ames, Iowa. “We are able to gather massive amounts of data very quickly,” she says. “My job in this project is to analyze the data that is gathered here at Iowa State and at other laboratories using computational analysis and bioinformatics. We can know every experiment computationally, and similarly, the variables involved.”

The project to which Wurtele refers is an ISU effort underway investigating the process of genetically stacking traits in algae for biofuels production. With a $4.37 million grant from the U.S. DOE, ISU genetics professor and project lead Martin Spalding intends to develop a micro-algal platform allowing algae to be treated as a crop. The best analogy to this is stacking traits in corn. “Farmers could plant simple unmanipulated lines of corn that have high yield,” Spalding says, “but you wouldn’t get the drought tolerance you want. You could plant drought-tolerant corn, but you wouldn’t get standability. But by genetically manipulating corn, you get all the traits you need.”

...A primary interest is how photosynthetic cells monitor their carbon status and regulate the genes involved in carbon assimilation in response to carbon availability. This is an example of metabolic regulation of gene expression, where products of metabolism act as signals in the regulation of gene expression. “We can perform very rapid, deep sequencing of the genes that are used to make proteins,” Spalding says. “And we can compare the results with other experiments. There are a lot of experiments that track the expression of genes.”

In Chlamydomonas, ISU is dissecting both the signal transduction pathway for adaptation to changes in CO2 and the microalgal “carbon concentrating mechanism” using insertional mutagenesis to generate tagged mutants subsequently relied upon to clone the key genes in the pathway. Identification of a key gene in the Chlamydomonas signal transduction pathway, cia5, has provided the opportunity to identify genes/proteins that interact with it using both suppressor analysis and the yeast two-hybrid system.

Of course, what Spalding and his team hope to accomplish is to increase the amount of lipid produced and the rate at which the algae produces it. When researchers dye the cells they can see “tiny droplets of oil.” It is here that a stain accumulates and causes a light scanner to “fluoresce” as it passes through the cells. “So we can pick out the cells with high fluorescents,” Spalding says. “It would be impossible to deal with any other way.”

This process of selection and isolation is the backbone of genetic engineering. The proverbial “needle in the haystack” are those genes that are involved in the biosynthesis of lipids. So, the relentless search for those candidates present in the biosynthetic pathway that could lead to faster growth and increased fat production precedes the work involved with isolating mutants and modifying the genes. “Screening technology has opened up a whole world,” Spalding says. “[Screening] a hundred million cells takes a couple of hours.”

...Ultimately, researchers believe the three-year study will produce many desirable traits in Chlamydomonas alga. “Our project will probably lead to increased production of basically vegetable oil that can be converted to biodiesel,” Spalding says. “Using the same process we are using to increase that oil production, we also could divert the production into hydrocarbons, which are closer to petroleum.” The end result could have several benefits. “It will mean we will have a more sustainable source [of energy] than we have now—more sustainable and more flexible,” he says.

These are the foundational studies which should prepare the way for business startups, pilot plants, and finally commercial-scale algal fuel plants.

Humans have very good experience with the microbial production of food, pharmaceuticals, and some chemicals, cosmetics, and food supplements. But those are generally a higher value product than fuels typically have been. Scaling up microbial production for cheap fuels will demonstrate a mastery of the microbial world that has been lacking up until now.

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