A recent study published in Advanced Energy and Sustainability Research explores how nutritional amino acids (AAs)—both essential (EAAs) and nonessential (NEAAs)—affect the breakdown of polystyrene (PS) by mealworms (Tenebrio molitor). Researchers found that the type and availability of amino acids significantly influenced the rate at which mealworms decompose plastic.
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Background
Mealworm larvae can digest certain types of plastic, including PS, during their development. This makes them a potential tool for reducing plastic waste and microplastic pollution through biodegradation.
However, plastic alone does not provide enough nutrients for mealworm larvae, which limits their ability to break it down efficiently. Researchers have tested supplementing their diet with natural food sources like sucrose, soy protein, wheat bran, chayote, and water, all of which have been shown to increase plastic consumption rates.
AAs, which are essential for many biological processes, might also help improve mealworm health and enhance plastic degradation. Until now, no studies have explored whether feeding mealworms individual free amino acids could boost their ability to break down plastic.
Methods
The study tested three EAAs—phenylalanine (Phe), tryptophan (Trp), and valine (Val)—and three NEAAs—cysteine hydrochloride (Cys), glutamine (Gln), and glutamic acid (Glu). Monosodium glutamate (MSG), an ionic form of Glu, was also included. Two control groups were established: one with only PS and another with PS and water.
Mealworm larvae in the PS group were given 0.4g PS cubes. In the experimental groups, AA solutions (2 mol/L) were sprayed onto the plastic three times a day. Over 10 days, researchers measured the remaining plastic, survival rates, mortality, and waste production daily. After 10 days, measurements were taken every five days until all the plastic was consumed.
At the end of the experiment, the larvae were starved for 48 hours to allow full digestion of PS, then frozen, dried, ground into powder, and stored for analysis. Researchers examined their dry matter (DM), crude fat (CF), and crude protein (CP) levels. They also used statistical models to compare plastic consumption rates and survival across the different groups.
Results and Discussion
The study found that adding AAs improved plastic biodegradation and helped maintain mealworm health. The effectiveness of different AAs in enhancing plastic breakdown followed this order: Cys < Gln < Glu < Trp < Phe ~ Val.
EAAs helped larvae survive longer, reduced cannibalism, and improved their plastic degradation efficiency by supporting metabolic pathways involved in plastic digestion. NEAAs like Glu, which are naturally abundant in mealworms, contributed to maintaining a balanced digestive environment, further aiding PS breakdown. This suggests that a combination of EAAs and NEAAs could improve both mealworm health and plastic degradation efficiency.
Some AAs, such as Cys and Gln, had little effect compared to just adding water. Among EAAs, Trp was the least effective, while Val and Phe showed stronger results. The study also found that reducing PS in the larvae’s diet while increasing protein content improved growth and waste degradation efficiency.
Overall, amino acid supplementation helped mealworm larvae survive longer while consuming plastic. In contrast, larvae that ate only PS had higher mortality rates and significantly lower body mass and fat levels, likely due to metabolic stress from an inadequate diet.
What's Next for Mealworm Plastic Recycling?
This study suggests that optimizing the diet of mealworm larvae could enhance their ability to break down plastic. Future research should focus on understanding the relationship between diet, gut bacteria, and plastic biodegradation, as well as using biotechnology to improve this process. These insights could lead to more effective and sustainable ways to manage plastic waste.
Journal Reference
Wang, X. et al. (2025). Enhancing Plastic Decomposition in Mealworms (Tenebrio molitor): The Role of Nutritional Amino Acids and Water. Advanced Energy and Sustainability Research. DOI: 10.1002/aesr.202400378, https://advanced.onlinelibrary.wiley.com/doi/10.1002/aesr.202400378
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