Toxin removing houseplant

Canadian regulators have granted approval for the use of a GM houseplant to scrub indoor air of hazardous pollutants.

The devil’s ivy, Epipremnum aureum, houseplants were genetically engineered to contain a protein sequence modified from a mammalian liver protein by University of Washington researchers (Environm. Sci. & Technol., 2019, 53(1), 325). The gene for the protein, cytochrome 450 2E1, came from rabbit DNA and was expressed throughout the plant – removing both benzene and chloroform in air.

‘In the mammalian liver, this gene codes for an enzyme that degrades a variety of small toxic molecules,’ says Stuart Strand, lead scientist at the University of Washington. He plans to commercialise the plants, initially in Canada. ‘Having a method to degrade a pollutant is not enough,’ Strand explains. ‘We are envisaging a miniature indoor glasshouse that might be the size of a window. It would have a fan that would help bring the pollutant into contact with the plant.’

The enzyme takes oxygen from air and uses it to oxidise benzene to produce a safer phenol compound used in plant growth. Meanwhile, chloroform disintegrates once it is attacked by the oxygen, generating carbon dioxide and chloride ions, which can be safety used by the plant.

Indoor volatile organic compounds such as benzene, formaldehyde, chloroform and ethylene dichloride come from various sources, including showering, washing, fuel storage and cooking, and may pose a cancer risk.

The GM houseplants and regular devil’s ivy were placed in glass tubes with either benzene or chloroform gas and tracked over 11 days. With GM plants, the concentration of chloroform fell by 82% after three days and was almost undetectable after six days, while benzene levels fell more slowly but were down 75% by day eight.

The concentrations of benzene and chloroform in the glass tubes were around a million times lower than in air, but Strand says: ‘We expect the same effects would occur, as the same kinetics apply at high concentrations as at low concentrations.’

Peter Irga, an air quality amelioration expert at the University of Technology in Sydney, Australia, describes the work as a great step in the right direction. ‘They have drastically improved the plant’s benzene removal, and the next step is to see how this may work in full sized rooms and in situ,’ he says.

Devil’s ivy does not flower in temperate countries, so the GM plant will not spread via pollen. However, the ivy faces a regulatory hurdle in the US, because it can grow outdoors in southern Florida. Strand says the team is looking for commercial partners to launch an air-cleaning device on the Canadian market.