One-time pest turned eco-warrior degrades polystyrene
Cockroaches have emerged as an unlikely hero in the fight against plastic pollution, as new research reveals the bugs’ gut microbes can rapidly degrade polystyrene.
From unwelcome house guest to eco-warrior, the cockroach (Blaptica dubia) harbors a powerful biological strategy for tackling plastic waste, Harbin Institute of Technology (China) and Stanford University (CA, USA) researchers have discovered. The unpalatable pests can degrade polystyrene via a tightly integrated enzymatic network, demonstrating their untapped potential for plastic bioremediation.
Plastic pollution is a global crisis, with micro- and nanoplastics ubiquitous in almost all ecosystems, posing a risk to both environmental and human health. Unfortunately, conventional methods for removing plastic contamination face bottlenecks, including high energy demand, slow kinetics and toxic byproducts. Polystyrene presents a particular challenge, being among the most difficult polymers to break down owing to its stable aromatic structure and resistance to natural degradation.
Biodegradation can help bypass these issues, offering a gentler, low-pollution alternative to plastic remediation. Several insect species, such as mealworms and wax moth caterpillars, can partially decompose polystyrene through their gut microbiota, although reported rates remain low. Cockroaches, with more stable gut microbiomes, longer lifespans and greater biomass, are a promising next candidate for investigation; however, their potential for scalable plastic bioremediation has remained unexplored.
To investigate the maligned critters’ biodegradation capacity, scientists integrated metagenomics, transcriptomics, 13C isotope signature and polymer chemistry analyses.
In controlled feeding experiments, 50 B. dubia roaches were fed a diet consisting of polystyrene powder with agar and deionized water for 42 days, while control groups featuring the same number of bugs were starved or fed on either a normal diet or just agar.
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To assess the occurrence and chemical characteristics of biodegradation, the researchers quantified changes in polystyrene molecular weight, examined stable carbon isotope signatures and characterized pyrolysis-derived products. Individuals in the experimental group ingested an average of 6.0 mg of polystyrene per day, removing 54.9% of the plastic mass over 42 days. This corresponds to a specific degradation rate of 3.3 mg per cockroach per day – far exceeding the rates seen in other plastic-feeding insects.
At the end of the experiment, cockroaches were sterilized and dissected. Then, the team used metagenomic sequencing to resolve changes in gut microbial community composition, functional gene profiles and microbe–enzyme interaction networks. This demonstrated that polystyrene exposure reshaped the gut microbiome, selectively enriching plastic-degrading taxa like Pseudomonas and Citrobacter.
Meanwhile, transcriptomic analyses of tissue samples to characterize host responses across pathways of energy metabolism, redox regulation and digestion, revealed that polystyrene ingestion upregulated host fatty-acid β-oxidation and tricarboxylic acid (TCA) cycle pathways. This allowed the roaches to directly metabolize microbial cleavage products and reconstruct a complete polystyrene catabolic pathway.
Taken together, the findings revealed that B. dubia rapidly biodegrade polystyrene microplastics via a tightly integrated gut microbe–host metabolic system.
“The cockroach does not simply fragment polystyrene – it metabolically processes the breakdown products through its own energy pathways. The coupling of microbial oxidation with host β-oxidation and the TCA cycle represents a systemic adaptation to synthetic carbon sources,” the study’s corresponding author Shan-Shan Yang explained.
“This work demonstrates that plastic degradation in insects is not merely a microbial phenomenon, but a fully integrated metabolic collaboration.” pollution
Not only does this highlight the potential of cockroaches for addressing plastic pollution, but it provides a methodological basis for investigating plastic-degrading capacities in other insect species as well.