2025 年 98 巻 12 号 p. 282-287
End-of-life tires (ELTs) represent a significant global environmental challenge due to their high volume, complex vulcanized structure, and resistance to biodegradation. While mechanical, chemical, and thermal recycling methods are established, their environmental impact and high energy demands have driven interest toward biotechnological approaches. Recent studies have identified key cis-1,4-polyisoprene-cleaving enzymes, Latex Clearing Protein (Lcp) and Rubber Oxygenases (RoxA, RoxB), and elucidated their molecular properties, cleavage patterns, and taxonomic distribution. Advances in understanding transcriptional regulation, particularly LcpR-mediated control, reveal conserved and divergent mechanisms across rubber-degrading bacteria. Downstream oxidation of oligo-isoprene aldehydes by aldehyde dehydrogenases (ALDHs) and OxiAB complexes is essential for complete rubber assimilation. Laboratory-scale biodegradation of unvulcanized rubber has achieved over 80% conversion under optimized enzymatic conditions, yet enzymatic degradation of vulcanized rubber remains largely unsuccessful. Challenges include sulfur cross-links, zinc oxide persistence, and additive toxicity, necessitating integrated physical–chemical pretreatments with multi-enzymatic systems. Drawing parallels to PET enzymatic recycling, recovery of oligo-isoprenoids for chemical upcycling presents a promising route for ELTs valorization. This review synthesizes current knowledge on enzymes, genetic regulation, and catalytic mechanisms involved in natural rubber biodegradation, highlighting both the potential and the technical bottlenecks in developing efficient, scalable bioprocesses for sustainable ELTs management.
