No matter where or when you are in the world, there are carcinogenic pollutants in the air. The natural degradation of plant material and other chemical reactions across the planet produce these compounds. This is also true for humans and the things we make and the homes we live in. The slow breakdown of laminate flooring, upholstery, and pretty much everything that makes up and is put in a home slowly puts out such compounds over time. Especially in regards to volatile organic carcinogens (VOCs) that are also a byproduct of cooking foods and even in the process of showering, such as formaldehyde and benzene.
Proliferation of Volatile Compounds
For the most part, the concentrations of these are at such a low level that they aren’t a concern, but there are certain situations that can cause a buildup of them. Thus, to reduce even minor potential risks of these to those that would be most vulnerable like children and the elderly, an easy method to collect and break down these compounds from air within a contained room would be useful. All of the current physical methods, including adsorption and photocatalytic oxidation have their downsides in complexity of application, the production of other problem components, or just require a large amount of energy in an unrealistic way.
Biological mechanisms have long been touted as a better and more passive option of cleaning household air through phytoremediation. However, even if plants can take up and break down VOCs, as one example, they do so at such a slow rate that the process isn’t feasible. Not unless one plans to have quite a lot of plants shoved into far too small of a room. The rates also vary by such a degree during controlled testing that there was no way to have a reliable set of plants to remove a known quantity of such compounds. There was just too much conflicting data from independent studies. So, regular, boring plants are out. But that isn’t the end of the discussion.
Plants themselves remain a hot commodity for air purification purposes just due to the excess energy they produce and have available for such tasks. Add to that the high amount of surface area they cover with their leaves and that they are self-sustaining and that makes them a far better product for this purpose than what microorganisms are capable of on the same scale. But how to boost the uptake and breakdown of such compounds if the plants aren’t capable of doing so naturally?
Researchers at the University of Washington decided to try an unorthodox, but rapidly becoming more commonplace, approach. There is a gene in mammals called cytochrome P450 2E1 or just CYP2e1 for short. It controls protein production for a protein that can oxidize a large number of VOCs and breaks them down so they do not damage the cell or the overall body. This gene has already been tested in trees through transgenic transfer and been shown to improve their VOC degradation. Now, they wanted to do the same thing for common houseplants and plants that would be more commonly found in urban areas and regions with higher VOC concentrations.
The houseplant they selected for the experiment was pothos ivy, due to its strong growth, ability to live in low light conditions, and because a genetic transformation method had already been conducted and published in the past for the species, saving a significant amount of time and effort on their part. Furthermore, since pothos ivy doesn’t flower in any capacity due to the ancestral loss of a necessary gene, there are no biosafety concerns of the transgene being spread through pollen production, however remote that risk would otherwise be. An enhanced green fluorescent protein (eGFP) was added to the transgene cassette as a selectable marker to show that the insertion had been successfully done.
The result was a highly active detoxification plant cultivar they named pothos ivy VD3. They tested it against two of the most common VOCs and the effect was incredibly strong when compared to wild type versions. Benzene breakdown increased 4.7-fold and chloroform was even more surprising as the wild type plants had no prior capability to break it down. VD3, meanwhile, reduced a concentration of 800 milligrams per cubic meter to 0 in the span of 6 days, an incredibly rapid degradation as well.
The Future Super Plants
While other VOCs were not checked in this particular experiment, it seems likely due to the functions of CYP2e1 in mammals that it would be able to break down any number of other compounds if given the opportunity and the researchers plan to make sure of that. They also hope to include a stronger GFP system in the plants, as the one they added was too weak to be seen with the visible eye under the right light and needed a microscope instead. They want it to be a visual marker under certain light to check for ongoing activity of the gene and also for biosafety reasons.
Lastly, they plan to try even more combinations of degradation genes beyond just this one. The gene faldh from a particular Bacillus bacterium has been shown to improve plant uptake of formaldehyde by several fold and that’s just by adding a single other option. Overall, the scientists have very clearly shown a simple, safe, and beneficial alternative to complicated and sometimes dangerous methods of cleaning contaminants and pollutants from the air, with the hopes that it will not only save lives and improve the health of people around the world, but that it might even be used to clean up contaminated regions of the planet at the same time.
Photo CCs: Money Plant (Epipremnum aureum ‘N’ Joy’) 2 from Wikimedia Commons