Soil fauna Protaetia brevitarsis mediated polyethylene microplastic biodegradation

Polyethylene (PE) microplastics (MPs), derived primarily from agricultural mulch films and other plastic debris, remain significant soil contaminants due to their resistance to degradation. This study reveals that soil-dwelling grubs (Protaetia brevitarsis larvae) possess a unique ability to degrade PE MPs with ultrahigh molecular weight (> 600 kDa) through synergistic interactions with gut microbes. Over a 28-day experimental period, the larvae consumed an average of 62.96 mg PE per grub daily, resulting in 28.6 % mass reduction of ingested PE-MPs. Molecular analyses of frass-residue MPs showed a 52.9 % decrease in weight-average molecular weight and oxidative functionalization (hydroxyl/carbonyl formation), while thermal profiles revealed biodegradation-specific byproducts, confirming extensive depolymerization. Antibiotic suppression delineated gut microbial contributions to PE-MPs degradation. Concurrently, gut microbiota restructured into Enterococcaceae-dominated consortia specialized in breaking down the polymers. Unlike previously studied surface-dwelling insects, P. brevitarsis naturally inhabits agricultural soil strata where plastic mulch residues accumulate, enabling in situ remediation without nutritional supplementation while maintaining physiological resilience through sustained survival rate and growth. Overall, we demonstrate PE-MP biodegradation by P. brevitarsis for the first time, illustrating the degradation mechanism mediated by both the host and gut microbiota. These results highlight P. brevitarsis as natural bioremediators for agricultural PE-MP pollution, presenting a sustainable approach to mitigate persistent microplastics with minimal ecological risks.