Spirulina regulates plastic degradation process in Zophobas atratus larvae: Gut microbiota, molecular responses, and...

Plastic degradation by insects often causes oxidative stress-induced intestinal damage, which harmed the intestinal function to limit plastic degradation. Herein, we investigated the potential of spirulina supplementation to alleviate intestinal damage and affect polystyrene degradation in Zophobas atratus larvae. Compared to wheat bran, spirulina supplementation more effectively reduced polystyrene-intake induced intestinal tissue degradation and epithelial shedding. Moreover, spirulina supplementation reduced molecular weight of polystyrene polymers detected in larval frass. Multi-omics analysis further revealed that spirulina significantly increased the levels of antioxidant compounds in the intestinal contents. Spirulina also suppressed pathogenic bacteria (Flavobacteriia and Pseudomonas) and enhanced beneficial digestive bacteria (Spiroplasma), thereby mitigating polystyrene-intake induced intestinal microbiota imbalance. Furthermore, spirulina upregulated larvae genes related to trehalose transporters and GATA-binding protein 4, promoting intestinal cell proliferation. Conversely, spirulina downregulated genes encoding Niemann-Pick C2 protein and F-BAR domain-only protein 2, which are involved in altering cell membrane morphology. Proteomic analysis indicated that spirulina supplementation altered the expression of multiple proteins involved in the one-carbon pool by folate pathway, steroid biosynthesis, and carbohydrate digestion and absorption pathways. These findings collectively demonstrated that spirulina supplementation effectively reduces intestinal damage caused by plastic ingestion and facilitates polystyrene degradation in Z. atratus larvae.