Evidence for microbial degradation of polyvinyl chloride (PVC) has previously been reported, but little is known about the degrading strains and enzymes. Here, we isolate a PVC-degrading bacterium from the gut of insect larvae and shed light on the PVC degradation pathway using a multi-omic approach. We show that the larvae of an insect pest, Spodoptera frugiperda, can survive by feeding on PVC film, and this is associated with enrichment of Enterococcus, Klebsiella and other bacteria in the larva’s gut microbiota. A bacterial strain isolated from the larval intestine (Klebsiella sp. EMBL-1) is able to depolymerize and utilize PVC as sole energy source. We use genomic, transcriptomic, proteomic, and metabolomic analyses to identify genes and proteins potentially involved in PVC degradation (e.g., catalase-peroxidase, dehalogenases, enolase, aldehyde dehydrogenase and oxygenase), and propose a PVC biodegradation pathway. Furthermore, enzymatic assays using the purified catalase-peroxidase support a role in PVC depolymerization.
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.
Microbial degradation of polyvinyl chloride (PVC) is eco-friendly and economically attractive but extremely challenging due to the lack of a molecular understanding of the degrading strains and enzymes. Motivated by the serendipitous discovery that the larva of an agricultural invasive insect pest, Spodoptera frugiperda, effectively survived PVC film alone, we profiled the intestinal microbiota of S. frugiperda larva and screened for PVC-degrading strains. Feeding on PVC film significantly changed the larval intestinal microbiota through selective enrichment of Enterococcus, Ochrobactrum, Falsochrobactrum, Microbaterium, Sphingobacterium and Klebsiella. From the larval intestine, we isolated the biofilm-forming Klebsiella sp. EMBL-1 and experimentally verified it as the first Klebsiella bacterium known to actively degrade and utilize PVC by various classic physicochemical and morphological analyses. We further used multiomic analyses, complementarily integrating genomic, transcriptomic, proteomic, and metabolomic insights, to identify enzyme-coding genes responsible for PVC degradation and proposed a biodegradation pathway for the bacterial strain. Overall, both S. frugiperda and strain EMBL-1 are first found to survive effectively on PVC film by using the polymer as the sole energy source. Moreover, this work exemplifying PVC biodegradation provides a reference for discovering more microbes and enzymatic resources for degrading other recalcitrant plastics.
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