Study on the dominant role and molecular mechanism of Lysinibacillus fusiformis Tm-07 derived from the gut of Tenebrio molitor in plastic degradation

Solid plastic waste has become a pressing environmental challenge worldwide. Tenebrio molitor possesses a unique ability to ingest plastics and straw. In this study, a dominant bacterial strain was isolated from its gut under the combined induction of polystyrene (PS), polyethylene (PE), and lignin, and was identified as Lysinibacillus fusiformis Tm-07. Genome sequencing revealed that Tm-07 harbors a wide range of genes related to carbon metabolism. Further investigations demonstrated that Tm-07 can form biofilms on plastic surfaces and secrete extracellular enzymes, thereby reducing surface hydrophobicity and generating new functional groups; notably, PS and PE as carbon sources significantly enhanced bacterial survival. Transcriptomic analysis revealed that multicopper oxidase laccase was the key enzyme markedly upregulated under PS, PE, and lignin conditions. Combined with degradation product analysis, the molecular mechanisms underlying Tm-07-mediated PS and PE degradation were elucidated, and a corresponding degradation model was proposed. This study provides an important microbial resource and molecular insights for plastic biodegradation.