Polyvinyl Chloride Biodegradation Fuels Survival of Invasive Insect Larva and Intestinal Degrading Strain of Klebsiella

Abstract

Microbial degradation of polyvinyl chloride (PVC) is eco-friendly and economically attractive, but extremely challenging due to the lack of mechanistic understanding on the degrading strains and enzymes. Motivated by an accidental discovery that the larva of an agricultural invasive pest, Spodoptera frugiperda, effectively survived solely on PVC film, we profiled the intestinal microbiota of S. frugiperda and screened for PVC-degrading strains. The results showed PVC film feeding significantly changed the larvae intestinal microbiota through selective enrichment of Enterococcus, Ochrobactrum and Klebsiella. From the larva intestines, we isolated and named a biofilm-forming strain EMBL-1, and experimentally verified it as the first Klebsiella bacterium that can actively degrade and utilize PVC based on various classic physicochemical and morphological analyses. We further used multi-omics analyses that complementarily integrate whole genomic, transcriptomic, proteomic, and metabolic insights to identify enzyme-coding genes responsible for PVC degradation and proposed a putative biodegradation pathway by the bacterial strain. All in all, both S. frugiperda and its intestinal strain EMBL-1 are discovered to effectively survive on PVC film by exploiting its polymer as a sole energy source. Moreover, this work exemplifying PVC biodegradation provides reference for discovering more degrading microbes and enzymatic resources of other recalcitrant plastics.