A novel cold-adapted esterase from Lysinibacillus pakistanensis VF-2 for efficient degradation of pyrethroid residues in tea leaves.

Abstract

Pyrethroid residues in tea have emerged as a significant safety concern due to their high lipophilicity and persistence, while efficient and mild enzymatic removal resources remain scarce. In this study, two novel esterase genes, gene3341 and gene2566, were identified from Lysinibacillus pakistanensis VF-2, both belonging to the α/β-hydrolase superfamily with a typical catalytic triad and conserved Gly-X-Ser-X-Gly motif. The recombinant enzymes Est3341 and Est2566 were successfully expressed in Escherichia coli, and exhibited β-cypermethrin (β-CY) degradation efficiencies of 77.97% and 71.92% within 7 days, respectively. Biochemical characterization demonstrated that Est3341 was a cold-adapted esterase with optimal activity at 25 °C and pH 7.0, enabling efficient degradation under mild conditions suitable for heat-sensitive tea matrices. Notably, Est3341 degraded 98.68% of high-concentration β-CY within 36 h, and its activity was significantly enhanced by Ca2+ and Mn2+. In tea leaf application, Est3341 removed 55.01% of β-CY, 59.40% of cypermethrin, and 46.23% of deltamethrin residues within 20 min at 25 °C. GC-MS analysis revealed that Est3341 hydrolyzed β-CY's ester bonds to yield 3-phenoxybenzaldehyde and other characteristic intermediates. This study provides a high-efficiency, mild-condition, tea-adapted esterase resource for green removal of pyrethroid residues in agricultural products, offering a promising strategy for food safety and environmental bioremediation.