Biodegradation of polystyrene microplastics by superworms (larve of Zophobas atratus): Gut microbiota transition, and putative metabolic ways.

Superworm (larve of Zophobas atratus) could consume foams of expanded polystyrene plastics. However, there is no sufficient understanding of the impact of microplastics on superworms and the degradation pathways of polystyrene. Herein, we explored the weight and survival change of superworms while fed with polystyrene microplastics, and found that survival rate and mean weight would reduce. In terms of gut microbial community structure of surperworms, significant shifts were detected with the relative abundance of Hafnia-Obesumbacterium sp. increasing. In addition, we domesticated two microbiota from the gut of superworms, and confirmed their ability to degrade PS in vitro. The last but most important, 1291 metabolites were identified by HPLC-TOF-MS/MS, and six metabolites related to polystyrene degradation were identified through comparative metabolomic analysis. According to the content and pathways of these metabolites, three metabolic pathways of polystyrene were (a) styrene-phenylacetyl-CoA-L-2-aminoadipic acid; (b) styrene-phenylacetyl-CoA-benzaldehyde; (c) styrene-2-hydroxyacetophenone. These results would help to further screen bacteria of PS degradation and investigate PS metabolic pathways in invertebrates.