Comparison of three insect larvae biodegrading polyethylene and role of the intestinal bacterial strains in polyethylene degradation by Galleria mellonella larvae

Abstract

Polyethylene (PE) has been described as the most abundant plastic worldwide, such as mulching films and plastic bags. A few insects have been identified to ingest and metabolize polyethylene. In this study, we contrasted the degradation ability of three insect larvae (Galleria mellonella, Tenebrio molitor and Zophobas morio) biodegrading polyethylene. The results demonstrated that G. mellonella has the best digestion ability on polyethylene. Eating and digestion of plastic products for a long time will inevitably cause negative effects on insects. The additional nutrients can improve the health of the PE-degrading insects, thus extending the digestion time of the plastic. Microbial degradation of polyethylene (PE) products has attracted much attention. Here, two bacterial isolates, Fictibacillus phosphorivorans A-2 and Pseudomonas sp. A-3 from the gut of PE-feeding G. mellonella, was suggested to utilize PE. Two bacterial isolates removed approximately 3.57 ± 0.30% and 2.00 ± 0.16% of PE films after 40 days at 30 ◦C, respectively. We demonstrated the ability for PE degradation of F. phosphorivorans A-2 at greater rates than Pseudomonas sp. A-3. The results suggest that supplementing the co-diet affected the physiological properties of the PE-degrading insect and plastic biodegradation. This study enriched microbial resources for PE degradation and provided promising evidence for the biodegradation of PE in the environment.