Ever wondered what happens to your takeaway container after you’re done with your meal? Single-use food packaging, commonly made out of polystyrene (styrofoam), is difficult to get rid of. Polystyrene isn’t biodegradable and once disposed of, it is usually incinerated by waste management processes that release toxic fumes and greenhouse gases into the air. In this way, polystyrene waste can damage sensitive ecosystems and contribute to the already devastating global plastic waste crisis.
To combat the plastic problem, scientists and environmentalists are searching for ways to convert polystyrene waste into fertiliser for agriculture use, achieving what is known as a circular economy. Towards this end, a team led by Samuel Gan, Senior Principal Investigator at A*STAR’s Antibody and Product Development Lab (APD), is enlisting the help of some unexpected allies: worms.
Certain worm species such as mealworms and superworms have been shown to consume polystyrene as a carbon source, naturally breaking down these plastics into nutrient-rich frass fertilisers. Furthermore, polystyrene does not need to be washed before being “fed” to the worms, saving both time and resources.
In their study, Gan and colleagues tested the feasibility of deploying worms to break down polystyrene waste. They were interested in how food additives found in human food affected the worms’ polystyrene consumption and whether the digestive waste-frass generated could support plant growth.
First, lab-grown superworms and mealworms were given a diet of only polystyrene balls. To simulate food packaging waste, some polystyrene balls were coated with common food additives such as cinnamon and sucrose. After four days, the researchers weighed both the worms and balls.
They found that the superworms had a sweet tooth—they consumed more of the cinnamon or sugar-coated polystyrene balls. The frass of these polystyrene-consuming superworms also showed better promise as a fertiliser. Dragon fruit cacti planted on superworm frass grew taller and had more rooting than those grown on mealworm frass.
According to Gan, these findings support the potential of a circular economy powered by nature. “Worms are a completely natural solution and can be set to work right away on the urgent growing plastic waste problem,” said Gan.
Gan’s team is optimising the worms’ growing conditions such as humidity and temperature, in the hopes of boosting their efficiency as polystyrene degraders. “We’ve already found a way to speed up the consumption of the polystyrene plastic up to five times using purely scalable environmental factors without needing to perform genetic modifications on the worms,” Gan added.
The A*STAR-affiliated researchers contributing to this research are from the Antibody and Product Development Lab (APD), Experimental Drug Development Centre (EDDC), Bioinformatics Institute (BII), and Institute of Materials Research and Engineering (IMRE).
