Plastic pollution has garnered global attention, yet the environmental threats posed by plasticizers remain largely understudied. Emerging plasticizers, such as tris(2-ethylhexyl) trimellitate (TOTM), are increasingly prevalent in anthropogenically impacted environmental reserviros, but their biodegradation mechanism and associated strains and enzymes are poorly understood. Here, we discovered Rhodococcus strain SPR1 from the gut of polyvinyl chloride (PVC)-consuming insect larvae, which exhibits broad-spectrum degradation capabilities across five representative plasticizers, including both traditional and emerging types. SPR1 achieved up to 63.07 % degradation of TOTM in 120 h, with two enzymes TOTMaseA (linear primary-alkylsulfatase) and TOTMaseB (α/β hydrolase), validated as key contributors. Enzyme kinetics revealed that TOTMaseA exhibited a Vmax of 2.655 mM and Km of 0.3821 µM/min, while TOTMaseB showed a Vmax of 0.9664 mM and Km of 0.2245 µM/min, confirming that TOTMaseA has superior catalytic throughput and serves as the dominant contributor to TOTM degradation. Notably, TOTMaseA also displayed consistently greater abundance compared to TOTMaseB under TOTM exposure. The widespread presence of homologous strains and enzymes of TOTM-degrading SPR1 in environmental samples underscores the ecological relevance and bioremediation potential. This study provides quantitative and mechanistic insights into the microbial degradation of TOTM and advances our understanding of enzymatic strategies that enable the breakdown of emerging plasticizers.
Keywords: Degrading enzyme; Microbial degradation; Plasticizer; Rhodococcus; Tris(2-ethylhexyl) trimellitate (TOTM).
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