Researchers have genetically modified a common houseplant – pothos ivy – to remove chloroform and benzene from the air around it.
Small molecules like chloroform, which is present in small amounts in chlorinated water, or benzene, a component of gasoline, build up in homes when we shower or boil water, or when we store cars in attached garages. The compounds are too small to be trapped in air filters, and both have been linked to cancer.
The modified plants express a protein (2E1) that transforms these compounds into molecules that the plants can use to support their own growth. The protein is present in all mammals, including humans.
In our bodies, 2E1 turns benzene into a chemical called phenol, and chloroform into carbon dioxide and chloride ions. But 2E1 is located in our livers and is turned on when we drink alcohol. So it's not available to help process pollutants in air.
"We decided we should have this reaction occur outside of the body in a plant, an example of the 'green liver' concept," said senior author Stuart Strand.
"And 2E1 can be beneficial for the plant, too. Plants use carbon dioxide and chloride ions to make their food, and they use phenol to help make components of their cell walls."
The researchers made a synthetic version of the gene from the rabbit form of 2E1. Then they introduced it into pothos ivy so that each cell in the plant expressed the protein. The researchers then tested how well their modified plants could remove the pollutants from air compared to normal pothos ivy.
They put both types of plants in glass tubes and then added either benzene or chloroform gas into each tube. For 11 days, the team tracked how the concentration of each pollutant changed in each tube.
For the unmodified plants, the concentration of either gas didn't change over time, but for the modified plants, the concentration of chloroform dropped by 82 per cent after three days, and it was almost undetectable by day six.
The concentration of benzene also decreased in the modified plant vials, but more slowly: By day eight, the benzene concentration had dropped by about 75 per cent.
Plants in the home would also need to be inside an enclosure with something to move air past their leaves, like a fan.
"If you had a plant growing in the corner of a room, it will have some effect in that room," explained Strand.
"But without air flow, it will take a long time for a molecule on the other end of the house to reach the plant."
The team is currently working to increase the plants' capabilities by adding a protein that can break down another hazardous molecule found in home air: formaldehyde, which is present in some wood products, such as laminate flooring and cabinets, and tobacco smoke.
"These are all stable compounds, so it's really hard to get rid of them," said Strand.
"Without proteins to break down these molecules, we'd have to use high-energy processes to do it. It's so much simpler and more sustainable to put these (air cleaning) proteins all together in a houseplant."
Pothos ivy grows well in all conditions, but doesn’t flower in temperate climates so the genetically modified plants won’t be able to spread via pollen. - Science Daily