Unveiling Gut Microbiota and Metabolic Functions Contributed to Polyvinyl Chloride Degradation in Spodoptera frugiperda Larvae

Background: The surge in synthetic plastic waste, especially polyvinyl chloride (PVC), poses severe environmental challenges. Recent discoveries in microbial biodegradation offer a hopeful approach to managing such pollutants. Notably, the gut microbiota of certain insect larvae have demonstrated potential for degrading PVC. However, due to challenges such as the significant variations in the microbial composition and low microbial biomass in the guts of insect larvae, there are currently no viable PVC-degrading biological resources derived from insect gut microbiota. Results: This research entailed sampling Spodoptera frugiperda larvae at various places and obtaining samples from multiple microbial habitats, employing 16S amplicon analysis to disclose the environmental influence on the larvae’s microbiota. Subsequently, we compared the changes in gut microbiota of S. frugiperda larvae and T. molitor larvae after consuming PVC, discovering that despite completely different microbial communities, they enriched similar functions. We then isolated Enterococcus casseliflavus EMBL-3, which was enriched in the gut of S. frugiperda larvae and verified that the NAD-dependent oxidoreductase it encodes can dechlorinate and degrade PVC. Conclusions: Besides emphasizing the stability of the microbiota in the midgut contents of S. frugiperda larvae in natural environments, this study leverages the gut microbiota resources of S. frugiperda larvae to discover an enzyme capable of degrading PVC, paving new paths for understanding the mechanisms of plastic biodegradation and advancing biotechnology to reduce global plastic pollution.