The Strength of the Strain
Margaret McCormick, chief operating officer of Targeted Growth Inc., was standing at a podium explaining the breakthroughs her team had made with cyanobacteria to a large crowd seated in a fancy conference hall in a downtown Seattle hotel in January, and after revealing the difference between a typical strain of cyanobacteria and a strain modified by Targeted Growth, McCormick had the entire crowd laughing. It was her description of that modified cyanobacteria that incited laughter from the crowd. Instead of a term more closely resembling the idea of “superiority,” or “advanced,” she pointed out to the crowd that her strain was significant because the strain featured a nice, fat beer belly. The funny thing is, she couldn’t have described the algal cell any better. More importantly, it is work like Targeted Growth’s to produce an algal cell with such a massive amount of lipid content that it coincidentally resembled McCormick’s description that will undoubtedly contribute to the scale-up of the algae industry, regardless of how it’s described.
McCormick and her team, which, since January, has formed an entirely new company based on their algae-strain success, aren’t the only innovators focused on the algae biology portion of the value chain. There are a number of private entities, national labs and university-led programs searching for the ultimate strain. Some are focused on DNA and others on photosynthesis antenna length, and even others who just want to work with those focused on DNA or photosynthesis antenna length. And there is a reason why strain selection continues. As McCormick mentioned in her presentation, “Environmental isolates of algae are not good enough” to meet the industrial requirements of algae’s next step, scale-up. Think of it this way: a major league baseball player wouldn’t step into the batter’s box with a tree limb from the backyard for a bat, although in theory it could work, just like a random strain of algae from some backyard pond might as well.
So while other developers flesh out the ideal length for a raceway pond or build new extraction systems via novel theories linked to cavitation, there is still reason to watch what those like Targeted Growth are doing, especially if one wants a glimpse into what the industrial strength strains of the scaled-up era will look like.
Hitting the Mark
“About five or six years ago we decided to get into the bioenergy space,” explains McCormick, “and then about three years ago we started putting our molecular biology expertise towards algae, and more specifically, cyanobacteria.” Now, led by McCormick, the group from Targeted Growth is branching out to focus exclusively on algae. “When we started the program,” she says, “the idea was always that if we met our objectives, which were demonstrating proof of concept that we could engineer those superior strains—and that it looked like the algae industry was actually going to become a reality—then we would do the new company.”
That new company has gotten off to a good start, and they have done it in a way similar to other superior strain seekers. “We have spent most of our emphasis on the lipid production so far,” she says. Those pathways that affect lipid production have been explored for a number of years, but the company’s work on the accessory pathways in combination with the workable cyanobacteria strain is what McCormick believes sets her algae team apart. “The main advantage of cyanobacteria is that all the tools are there for genetic manipulation.” And the team has tried several. The strain features three manipulations, ranging from putting in new pathways, changing the timing of gene pathways so that you are turning the gene on or off during specific times of development, or even taking genes out, explains McCormick. “We believe it is the various combinations that are going to make these strains successful.”
One of the manipulations the team has already worked on has been to delete the cell’s ability to convert surplus carbon into glycogen. The team deleted the GlgC gene, essentially helping the cell to allow that surplus carbon to become oil instead of glycogen. “Our chief scientist says the only limit that we have is our imagination,” McCormick says of the potential of the company’s work on cyanobacteria, because “all the tools are in place.”
TLA 3 is Coming
Not all algal strain development is about lipid content. Some research efforts are looking to develop weather tolerant strains, and others like UC Berkeley’s Tasios Melis have been spending time developing TLA in microalgae, or truncated light harvesting antenna. “The concept of TLA in mass culture prevents the early light saturation of photosynthesis,” Melis says. “It facilitates better light penetration.” Better light energy equals better algae energy, according to Melis, which could come in the form of biomass, hydrocarbons or even pure hydrogen gas. The idea behind TLA work starts with chlorophyll levels in the microalgae. Chlorophyll acts as a sunlight absorber in the cells, essentially limiting (based on the amount of chlorophyll arrays present in the cell) the amount of sunlight that can actually be used by the cell for growth.
By truncating the sunlight receptors—the antennas—of the chlorophyll, Melis learned that sunlight could penetrate further into the cell and allow for more growth, 300 times more. More important to Melis’ work is the fact that he has something in common with TGI. Melis proved the effects of a mutated TLA microalgae cell. He’s also made the cell available. His team put the TLA 1 strain into the chlamydomonas library just last year, and the strain has already been acquired by five universities, five private businesses and four government labs.
Typically, Melis says, there are 600 chlorophyll units in a cell, and his goal is to reduce that level to 130. To do that, Melis started with DNA manipulation of the microalgae. There are genetic determinants, he says, that determine the size of the antenna. By inserting a piece of DNA into the nucleus of the microalgae cell the team forced the cells to mutate, and change the genetic makeup of the cells. The idea, Melis says, was to mutate the cells so a truncated antenna would be formed and then they could isolate those mutated cells. “This is easier said than done.”
During the first round of insertions nearly 10 years ago, it took the team roughly 6,500 screenings to find one bona fide TLA. The team tested the TLA mutant versus a wild strain and the results were startling. “In the period of time it took each to reach the same level of density, the wild type accumulated 6.36 million cells per milliliter,” he says. “In the same amount of time the TLA accumulated 10 million cells per milliliter,” adding that, “the productivity, no matter how it was measured by three different approaches, appeared to be double that of the wild type under bright sunlight and under mass culture conditions.”
Initially the team thought it would take until 2015 to reach the desired levels of chlorophyll units (130), but fortunately they were wrong. In 2005, the team had engineered TLA 2 which lowered chlorophyll units to 195 and in 2008 they did it again, creating TLA 3 that reached all the way down to 150 units. It takes a number of years for testing and accreditation of scientific work like his to be certified and ready for public use, Melis explains. The TLA 3 strain that is on the way will, he says, be applied to biomass, hydrogen production for microalgae and even cyanobacteria.
No one hopes companies or researchers like TGI and Melis succeed more than Karen Newell-Rogers, because Rogers has discovered a cocktail of compounds that when added to virtually any algae strain, will improve the lipid content. Her work on metabolic disruption technology (MDT) started in tumor research and was funded in part by Viral Genetics, but after applying her findings to algae, Viral Genetics thought it was so promising the company formed VG Energy to commercialize MDT.
In tumors, the process prohibits the tumor cells from burning fats, hindering the ability of the cell to generate the energy needed to fend off drug treatments like chemotherapy or radiation. In algae, MDT limits a cell’s ability to burn fats and, as McCormick has shown, everybody likes a “fat” algae strain. Rogers says that there is a very important protein that facilitates the use of fat that is highly expressed in drug-resistant cells, called a mitochondrial end coupling protein. “The drug-resistant cells are very capable of switching to the end-coupling protein as a method to burn fat,” Rogers says. She began looking at plants under stress from extreme temperatures, from too much humidity and other conditions and found that plants have the same capacity to switch their source of energy to fatty acids as a mechanism for survival. “So we began to look at algae,” she says, “and the first thing we discovered is that algae also have end coupling proteins,” and she started to test her MDT approach at blocking pathways to those proteins.
“If I put in the same kind of inhibitors that would block burning fat in a tumor cell,” Rogers says, “we can also block burning fat in those algal cells, and if we increase the concentration of the inhibitor, not only do they accumulate oil, they begin to secrete the oil in little droplets.”
To prove her work, Rogers has been working within the Texas A&M Agrilife facility where scientists have shown how well the MDT process works. The process involves treating algae with synthetic compounds, Rogers explains. “They are metabolized and then they go away. We are not doing any kind of genomic modifications.” She equates the process to adding fertilizer to a farm that is trying to produce oil. We can enrich the oil content on a per-cell basis roughly threefold, she says.
For the period of time the algae are affected by the inhibitors, they can’t burn oil, and that is an advantage of using an MDT inhibitor approach. “We can harvest the algae and we can either extract the oil or put in sufficient compounds where they spit oil out themselves. And that is a big advantage over trying to come up with a use for the biomass of dead algae.”
Regardless of the approach used by companies like VG Energy or researchers in California, there are several things to remember about all of those efforts devoting thousands of beakers a year to algae. For one, these are the type of companies that will form partnerships, at least in VG Energy’s view. Haig Keledjian, spokesperson for VG Energy, says not only does the company hope to partner with an established player in the young industry, but that companies like VG Energy “are not in competition with the companies out there, we are an enhancer.”
McCormick has her take on algae biology companies too. She asks the question, “If we build it, will they come?” If the work by companies like Targeted Growth, VG Energy or a handful of research efforts as good as UC Berkeley’s are any indication, it seems awfully hard to say no.
Author: Luke Geiver
Associate Editor, Algae Technology & Business