by Sarah Loftus -- April 3rd, 2014
Publicized opinions and studies on the impacts of genetically modified foods are as abundant as the white flowering trees saturating Duke’s campus. The amount of publications on the impacts of genetically modified algae for biofuels is more comparable to the abundance of Venus flytraps on campus (check out the small ‘Carnivorous plant collection’ in Duke Gardens). Algal biofuels are nowhere near the scale of production of genetically modified foods, but algae biofuel companies across the globe are planning for future scale-up. Genetic modification of algae follows similar concepts as crop modification, with similar uncertainties too. Though modification could increase renewable fuel production, further examination of the impacts of growing massive quantities of non-native and genetically modified algae is needed.
We genetically modify organisms to serve our needs more effectively and efficiently. One way of doing this is to insert genes that allow the organism to produce certain materials, or that make it more likely to survive. For example, bacteria modified with human insulin genes have been used to produce insulin for diabetes patients since the 1980s. Algae can be modified with genes that allow them to make chemicals for warding off harmful bacteria, improving their chances of survival.
Another way of genetically modifying an organism is to stop certain genes from being expressed, meaning they can no longer instruct cells what to do. For example, researchers were able to prevent the production of lipases in algae through genetic modification. Lipases break down the fats in algae that are used to make biodiesel. If algae can’t break down these fats, the fats accumulate and biodiesel production increases.
Organisms used to make biofuels must be highly productive and robust. Genetic modifications help achieve this objective by increasing fitness (ability to survive and reproduce), growth rates, and production rates of fuel ingredients such as fatty acids. Some algal biofuel companies are currently using genetically modified algae in testing and demonstration facilities, though specific details of their technologies are propietary so are not available to the public.
Most of these companies grow the modified algae in enclosed photobioreactors (photo), where theoretically they will not come into contact with the outside environment. In a previous post I explained how algae grown in outdoor pond reactors (open to the environment) are susceptible to contaminants like bacteria. You can imagine how easily it could work in the opposite direction: microscopic algae escaping from the reactor in droplets picked up by a strong wind gust or the leg of a flying insect. Photobioreactors can prevent algae escaping to the environment better than open pond reactors can, but accidents and algae spills are still possible and have uncertain ecological consequences.
Algenol Biofuels, Inc. designed genetically modified cyanobacteria that secrete ethanol and can be used to make crude oil after their ethanol-production days are over. The modified cyanobacteria divert their carbon to ethanol-producing fermentation instead of cell maintenance. This gives the cyanobacteria a major advantage in producing ethanol fuels, but means they wouldn’t stand a chance in the environment where they are not being pampered. The genetic modification therefore comes with a safety net of the organisms not being able to survive in the wild.
Unlike Algenol that is using photobioreactors, Aurora grows its algae in open pond reactors. They’ve used both genetic modification and selective breeding to create more productive algae strains. The company aims to produce health foods, fish feed, and pharmaceuticals in addition to biofuels. Sapphire Energy, on the other hand, is completely focused on fuel. This company uses selective breeding and strain engineering to create algae strains that can resist predators and disease, are harvested with less energy, and create fuel compatible with existing energy infrastructures. One more example: Solazyme is another company using modified algae. This company feeds algae sugars from various sources, so that the algae produce oils in the dark and don’t photosynthesize. Genes inserted into these heterotrophic algae come from plants and yeast.
Evaluating and Minimizing Risks
With researchers and companies turning to genetically modified algae to make more fuel, some scientists are advising how these organisms should be tested to evaluate and eliminate possible risks. Risk is the product of probability and impact. Companies can minimize the probability of modified algae escaping to the environment, but if we do not know what impact these algae have we cannot accurately measure the risks.
A spill of zero-risk algae would be like a one-time nutrient pulse from wastewater or fertilizer runoff. It’s not good, but it won’t create a permanent change in ecosystem health pervasive across all trophic levels. The lowest risk algae are those that can’t survive in the environment and can’t pass on or transfer their genes to other microbes. The highest risk algae are those that can become invasive, adapt to the environment through natural selection, and transfer their genes to native microbes. Algae that have been modified to resist predators and ward off bacteria have a high risk because these traits might give them an advantage over native algae.
However, genetically modified algae can be designed to have minimal chances of surviving outside of their reactor. They can be engineered to lack genes necessary for transforming certain nutrients in the environment into the form they need. In a reactor, the nutrient form they need is fed to them directly, but in the environment they couldn’t survive. It’s kind of like raising Chihuahuas in your home on dog food and then releasing them into the wild- there’s a very slim chance they’ll be able to fend for themselves or reproduce. Algae can also be engineered with “suicide genes” that trigger death when algae are exposed to the environment.
It’s hard to make predictions about what will happen without introducing the modified algae to the environment. Lab experiments cannot capture all the complexities and available niches in the environment that may help algae survive. Still, comprehensive experiments with artificial ecosystems need to occur. Furthermore, risk assessments need to include all non-native algae that will be grown for biofuels, not just genetically modified ones. Like Kudzu, invasive species don’t have to be genetically modified to alter an ecosystem.
There’s no easy answer for what risk assessments qualify as thorough enough. At some point the EPA, USDA, and FDA will make regulatory decisions. And risks might be weighed against the environmental benefits that algae provide over fossil fuels: would algae spills be worse than an oil spill? As the authors of Cradle to Cradle say, regulations are a red flag. They indicate that something is not safe for humans or ecosystems at some concentration. The ultimate proof that algae grown for biofuels have no negative consequences will not be seen until regulations are no longer necessary.