Wheat bran supplementation improved polystyrene degradation efficiency of Zophobas atratus larvae by alleviating intestinal injury caused by polystyrene-intake

Wheat bran supplementation significantly improves the polystyrene consumption capacity of Zophobas atratus larvae. However, the underlying mechanism remains unclear, limiting further advancements in degradation efficiency. This study seeks to clarify the mechanism by analyzing intestinal morphology, gut microbiota structure, gene transcription, and targeted metabolites. Specifically, histopathology results demonstrated that wheat bran supplementation alleviated polystyrene-induced intestinal injury in larvae. From a genetic perspective, genes related to annexins and tight junction proteins were upregulated in intestinal tissues. These genetic changes positively correlated with increased levels of short-chain fatty acids, eicosanoids, and beneficial bacteria (e.g., Latilactobacillus curvatus). Moreover, wheat bran supplementation alleviated gut microbiota dysbiosis, suppressed pathogenic bacteria, reduced over upregulation of NADPH oxidase activity related genes, and up-regulated genes linked to the intestinal immune system process pathway, thereby mitigating the intestinal injury. It also upregulated genes associated with the aromatase activity pathway, promoting the degradation of polystyrene and its intermediates. In summary, wheat bran supplementation enhanced the polystyrene degradation efficiency of Z. atratus larvae by upregulating genes linked to the aromatase activity pathway and mitigating intestinal injury (through modulation of intestinal gene transcription, microbiota structure, and metabolites). Our findings offer new insights into improving the efficiency of insect-mediated plastic biodegradation.