The Bacteria (And Worms) That Can Save the World

Whenever you buy a bottle from a vending machine, put plastic wrap over your food, toss single-use plates and utensils in the garbage because you are too lazy to do the dishes, or simply throw away a broken rubber band that was once a slingshot, you are contributing to the ever-growing global waste problem—in this case, plastic waste. 

Currently, plastics are being consumed at an unprecedented rate; 50 percent of our total plastic waste is made up of single-use plastics only. At the same time, another material is making headlines: vulcanized rubber, which is commonly found in tires, rubber bands, and erasers. Vulcanization is the chemical process that physically strengthens rubber. Vulcanized rubber and plastic have strong chemical bonds, and their prolonged degradation time has led to their classification as “non-biodegradable.” The degradation time of plastics is up to 500 years, and for vulcanized rubber, it is 80 years. These lengthy decomposition times cause these materials to pile up endlessly in landfills, releasing carbon dioxide and methane, organic compounds that greatly amplify the effects of climate change. 

Fortunately, with new discoveries relating to rubber- and plastic-consuming superspecies, it is possible that these materials could soon become biodegradable. In this case, superspecies refers to species that are able to break strong bonds in vulcanized rubber and plastic to reduce their degradation time. Recent research has shown that superspecies like Cytostome P450-driven bacteria, the Ideonella sakaiensis 201-F6 bacterium, and the Acinetobacter sp. BIT-H3 mealworm can degrade polyethylene (PE), polyethylene terephthalate (PET), and vulcanized rubber. This is a breakthrough because each of these materials is commonly found in things like toys, bottles, and tires. 

Cytostome P450-driven bacteria primarily break down PE plastic. PE is extremely durable and has one of the longest degradation times of all plastics. Using oxidation, or the loss of electrons in a molecule, P450 is able to turn PE into simpler, nontoxic products. The main reason that P450 is important is because it can break down the C-H bonds (very strong carbon-hydrogen bonds that require around 113 kilocalories per mole to break) commonly found in plastics. While further research is needed to understand how powerful P450 truly is, it has great potential to serve as an important biological catalyst in eliminating PE plastics in landfills, the ocean, and other locations.

Another superspecies is Ideonella sakaiensis 201-F6, which has been found to break down PET plastics. In 2001, a biologist was walking through a landfill when he noticed something nibbling through the plastic bottles. Further research showed that in six weeks at 30 degrees centigrade, a new species of bacterium—that is, 201-F6—was able to consume a sheet of PET film. 201-F6 contains a biocatalyst called ISF6_4831, which gives 201-F6 its superspecies capabilities by breaking down complex polymers into monomers. 55 million tons of PET plastic were produced in 2021 alone, so this discovery represents the first step in prospectively removing this widely popular type of plastic from our landfills and nature. Implementing 201-F6 to break down PET is a definite possibility, and the genome of ISF6_4831 could even be modified to speed up the process.

Finally, Acinetobacter sp. BIT-H3 is able to break down vulcanized rubber by devulcanization (breaking down the bonds in the rubber), depolymerization (breaking down polymers into simple monomers), and assimilation (the absorption of nutrients by a molecule). Unlike other species that have been found to break down rubber, BIT-H3 can survive solely on the carbon in rubber, so no human intervention is needed to “feed” the species. When subjected to BIT-H3 for a 10-week period, rubber pieces lost around 12 percent of their total mass, whereas, without BIT-H3, the percentage was close to zero. In addition, BIT-H3’s degradation of rubber decreases its tensile strength—the maximum stress an object can withstand before breaking or stretching—from 78.2 million pascals to 36.6 million pascals (standard atmospheric pressure is around 101.325 kPa). BIT-H3 could be an affordable solution to breaking down rubber products quickly and shrinking waste in rubber landfills.

P450-driven bacteria, 201-F6, and BIT-H3 are all possible solutions to the immense plastic and rubber waste humans produce. Still, research through experimentation, genetic engineering, and more must be conducted before these species are ready to be used. Nevertheless, they do provide hope for an affordable, effective solution to plastic waste, which could save thousands of species suffering from habitat degradation, as well as the planet as a whole.