A Big Bang for Algae
Single cell photosynthetic organisms, such as blue-green algae, could play an important role in the future of our nation’s space program. Not only could they be used to supply valuable oxygen to fuel life-support systems, genetically modified microorganisms could also be used to produce long-chain hydrocarbons for use as fuel or as building blocks for plastics and other needed materials.
The National Aeronautics and Space Administration recently awarded a grant of $750,000 to a project led by South Dakota State University. Together with a variety of collaborators, the SDSU researchers will develop methods to use blue-green algae—also known as cyanobacteria—to produce, fuels, chemicals, oxygen, and cleaned water from carbon dioxide, sunlight and wastewater. While the technology could provide obvious benefits for America’s space program, the technologies that are being developed will also be applicable here on Earth.
According to Bill Gibbons, a professor in the biology and microbiology departments at SDSU and scientific principal investigator for the research, the project has two main objectives. “One is microbial engineering,” he says. “In that what we are doing is changing the metabolic pathway of the cynobacteria that we are using from producing storage carbohydrates to producing long-chain hydrocarbons or alcohols. The second aspect is the system engineering. That involves developing a re-circulating photobioreactor integrated with a separation system, and then linking that with an ability to get light [into the system].”
The grant, which was awarded through NASA’s Experimental Program to Stimulate Competitive Research (EPSCoR), is actually supporting a three-year project proposal submitted by the South Dakota School of Mines and Technology. However, the majority of the work will be carried out by SDSU. Gibbons specifies David Salem and Robb Winter from the School of Mines will be contributing in the area of polymers. Their area of focus is polymer chemistry, he says. “They will be working with us on polymers and manufacturing the polymers that we would use to construct the biobioreactors,” and how other technologies will be integrated with the system.
Dieg Sandoval from the Oglala Lakota College will also be contributing to the project. “He is going to be working on the analytical side, so he’ll have students who come here during the summers and learn what we are doing in terms of engineering, and the organisms, and engineering of the systems,” Gibbons says. “They will also assist us on the analytical side throughout the rest of the year. We’ll be able to send them samples of the culture fluid (to test)”.
A fourth educational institution will also be taking part in the project. Students and teachers from Flandreau Indian School will be participating in the project during the summer months by working in the research labs. The school’s superintendent Betty Belkham will be coordinating the internship program. According to Gibbons, the hope is that participation in the project will help encourage more Native American students to become interested in continuing their science educations. “Both the Oglala Lakota and Fladrew Indian School efforts are research efforts, but they are also directed at trying to explain this opportunity, showcase this opportunity, and build a pipeline of Native American students to be interested in pursuing this as a career, because we see this as not just the application in space, but on earth as well,” Gibbons says.
Additional partners in the project include SDSU researchers Ed Drake, Gary Anderson, Zhengrong Gu, Kasiviswanathan Muthukumarappan, Xingzhong Yan and Ruanbao Zhou. Raven Industries’ Gary Kolbasuk and ICM Inc.’s Doug Rivers will also contribute to the manufacturing of the photobioreactor, working on process integration for Earth applications.
Gibbons notes that the name of the photosynthetic microorganism his team is working with is slightly misleading. Although commonly referred to as blue-green algae, cyanobacteria is technically not algae. Most living organisms can be grouped into one of two categories; prokaryotic or eukaryotic. According to Gibbons, bacteria—including cyanobacteria—are prokaryotic organisms while algae are eukaryotic organisms. The eukaryotic group, which also includes fungi, plants, animals and humans, represent much more complicated systems, and are much more difficult to genetically modify.
One of the reasons our team has chosen to work with cyanobacteria is that photosynthetic bacteria is much easier to genetically manipulate, Gibbons says. They also grow much more quickly than traditional algae, so their productivity has the potential to be higher.
“We are going to do engineering on the cyanobacteria and then we’ll optimize its performance using directed evolution,” Gibbons says. “Hopefully we’ll have a very productive and robust strain. One of the challenges is that microorganisms can be very finicky to work with. One of the challenges in working with all microbes is getting them to the point where they are hearty enough to use on an industrial scale.”
While traditional algae processes aim to grow algae, recover the algae cells, recover the oil from the cells, and then use a biorefining technique to convert the oil into a fuel or chemical product, Gibbons says the technology being developed by his team is much simpler. “We are basically bypassing all those steps by having the microbe produce [finished products] directly,” he continues. The modified and optimized blue-green algae that the team develops will be capable of secreting long-chain alcohols or hydrocarbons directly into the culture fluid. Since the products the team is targeting are not soluble in water, Gibbons says phase separation can be used to recover the products.
In addition to engineering a microbe to excrete fuels, the project also involves the design of a photobioreactor system that will be used to cultivate the cyanobacteria. “In the space application, we are looking at using optical fibers that would gather the light and transmit it to the photobioreactors, and then disperse it,” Gibbons says. The patent-pending process, referred to as wavelength shifting technology, uses a chemical process to change the wavelengths of ultraviolet, near infrared and infrared light into photosynthetically active wavelengths. “What we are doing is taking a broad spectrum of radiation that is in the sunlight and converting some of those unusable wavelengths into photosynthetically active wavelengths.”
Regarding space application, the design of the photobioreactor will also need to address separation loops, a method to bubble in CO2-enriched air and a method to pull off the oxygen. “One of the features that we are looking at for the space application is how to separate the CO2 and the oxygen that exhausts through the system,” Gibbons says. “The algae won’t use 100 percent of the CO2 that is being bubbled into the reactor, so on the outlet side you will have oxygen that they produce, plus some residual CO2. It would be nice to be able to separate those two so you could have pure oxygen going back into the crew compartment.”
The initial stage of the NASA-funded project, which officially kicks off Nov. 1, will tie these existing research components together. “Each of these technologies is being worked on kind of separately right now,” Gibbons says. “In the initial stages, we will be putting together a bench-scale system that will integrate all these technologies together.” He estimates the bench-scale development will take between a year and a year-and-a-half. The next step will be to develop a 50- to 100-gallon, pilot-scale photobioreactor system. Once operational, Gibbons says the pilot system will be used to complete material, energy and cost evaluations. “Of course, there would be another scale-up step before it would go commercial, but that’s kind of where we want to be at the end of three years,” he says.
Applications in Space, and on Earth
The technologies and processes developed though this project could have important implications both in space and here on Earth. According to Gibbons, the cynobacteria strain SDSU researchers are engineering will be employed in a unique photobioreactor system on Earth that has been developed by a team led by Bioengineer Researcher Jonathan Trent at NASA’s Ames Research Center. The technology, referred to as Offshore Membrane Enclosures for Growing Algae, involves using biobioreactors in the ocean to grow algae.
Secondary treated wastewater is pumped into the reactor, which features an osmotic membrane. “It will actually pull the fresh water out of the waste water, so it ends up releasing clean water into the ocean, keeping the nutrients inside for the algae to grow,” Gibbons says. “As the fluid passes from one [photobioreactor] floating out in the ocean to the next, it procures algae cells.” While the system was designed to employ traditional algae, Gibbons says his team will work with Trent to see if the photobioreactor system could be used to cultivate the microbe engineered at SDSU.
According to Gibbons, the research team is also working with a few local ethanol plants to evaluate the possibility of utilizing their CO2 to grow cyanobacteria in a photobioreactor on Earth. While the photobioreactor system under development by the team will have obvious applications in space, Gibbons stresses that the wavelength shifting technology could be applicable on Earth as well. “One of the big advantages of this technology is that it improves the efficiency of light transmission,” he says. “The other side benefit that we get out of it is reduced heat buildup, because we are taking some of the infrared radiation, which can otherwise actually be a problem in a greenhouse [or photobioreactor].” They can get too warm, which can stunt the growth of the algae or microbe culture. “Regardless if it’s on Earth or in space, [the system] will help us reduce heat buildup while converting that energy into photosyntheticlly useable energy.”
If established on a different planet or the moon, Gibbons notes the photobioreactor system would actually be located underground. “You’d gather the light on the surface with solar collectors, transmit it through these light fibers to the underground protected location where you could maintain the temperature and wouldn’t have to worry about all the other issues [associated with locating] on the surface,” he adds.
Although Gibbons and his team are working with cyanobacteria rather than algae, he says that the photobioreactor system developed as part of the project could also be used to cultivate algae. The wavelength shifting technology could also be applicable to algae production systems. According to Gibbons, the technologies that result from this project are expected to be available for licensing once patented. “We are definitely interested in and willing to work with people on using those technologies.”
Author: Erin Voegele
Associate Editor, Algae Technology & Business