Collaborative biodegradation of wheat straw by insect-derived cellulolytic enzymes and lignin-degrading bacteria in the gut of Zophobas morio

Superworms (Zophobas morio) are edible insects that hold promise for sustainable bioconversion of agricultural waste. However, its ability to degrade recalcitrant lignocelluloses, such as straw, remains poorly understood. In this study, we demonstrated that Z. morio larvae efficiently utilized wheat straw without a survival cost. We first profiled the gut transcriptome of Z. morio larvae to uncover this mechanism, and identified a host-encoded, midgut-specific lytic polysaccharide monooxygenase, ZmLPMO15-2I, which was significantly upregulated in response to straw feeding. Functional characterization confirmed that ZmLPMO15-2 oxidatively cleaves cellulose and synergistically boosts its glycosyl hydrolase activity. Its functional role in the degradation of straw cellulose by Z. morio was further validated by RNAi knockdown and subsequent rescue via bacterial replenishment. Concurrently, the gut microbiota of straw-fed larvae shifted significantly, becoming enriched for Kluyvera . Using culturomics, whole-genome sequencing, and structural characterization, we isolated a novel lignin-degrading bacterial strain, Kluyvera sp. Zm8 in the gut of straw-fed larvae. A novel cooperative model has emerged whereby host enzymes target cellulose, whereas symbiotic bacteria dismantle lignin, enabling efficient lignocellulose breakdown in Z. morio . Superworms Zophobas morio larvae could efficiently biodegraded lignocellulose-rich wheat straw. A host-derived enzyme ZmLPMO15-2, which was strongly upregulated during straw ingestion, proved essential for cellulose degradation in Z. morio and larval adaptation to straw-based diets. Furthermore, a novel lignin-degrading bacterium, Kluyvera sp. Zm8, was isolated in the straw-fed larval gut and functionally validated. Gut-derived cellulolytic enzymes and symbiotic lignin degrading bacteria cooperatively enable efficient lignocellulose breakdown by Z. morio larvae. This study provides novel insights into the mechanisms of lignocellulose bioconversion by edible insects and offers sustainable strategies for agricultural waste management with low carbon footprints.