ABTS mediator enhances biotransformation of fluoranthene by Laccases from Trichoderma lixii FLU1 and Talaromyces pinophilus FLU12.

Fluoranthene poses a significant environmental threat due to its persistence and toxicity. The Laccases from Trichoderma lixii FLU1 (Tl FLU1L) and Talaromyces pinophilus FLU12 (Tp FLU12L) are shown to act as biocatalysts for fluoranthene degradation. 3 U/mL of Tl FLU1L and Tp FLU12L reduced residual fluoranthene concentration to 49.5 ± 8.68 and 61.0 ± 5.66 %, while 10U/mL to 19.2 ± 5.95 and 28.7 ± 1.25 %, respectively, in 96 h. Mixing 200 μM ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) with 3 U/mL enzyme in the reaction abolished 100 % residual fluoranthene within 48 h. Tl FLU1L and Tp FLU12L exhibited almost similar v max (1.35 ± 0.02 and 1.29 ± 0.15 mg/L/h, respectively), but Tl FLU1L showed a lower K m as compared to Tp FLU12L (119.2 ± 0.02 and 170.8 ± 0.15 mg/L, respectively). ABTS significantly increased v max to 7.73 ± 0.23 and 7.97 ± 0.28 mg/L/h, and decreased K m to 54.8 ± 0.27 and 26.6 ± 0.21 mg/L for Tl FLU1L and Tp FLU12L, respectively. GC-MS analysis revealed that Tl FLU1L generated metabolites 9-oxo-fluorene-1-carboxylic acid, 9H-fluoren-9-one, and phthalic acid while Tp FLU12L produced 9,10-phenanthrenedione and benzene-1,2,3-tricarboxylic acid. Ecotoxicity and cytotoxicity analysis of Tl FLU1L and Tp FLU12L degradation products in the presence of the mediator (ABTS) are found to be non-toxic towards marine bacteria (Vibrio parahaemolyticus) and HT22 cells. Thus, the study underscores the promising potential of Tl FLU1L and Tp FLU12L, particularly in conjunction with mediator (ABTS), for environment friendly and efficient bioremediation of fluoranthene-contaminated environments. • Laccases from Tl FLU1 and Tp FLU12 efficiently bio-catalyses Fluoranthene. • Mediator (ABTS) enhances Laccases efficiency for substrate Fluoranthene. • ABTS reduces K m and enhance v max of Tl FLU1L and Tp FLU12L for Fluoranthene. • Tl FLU1L generated 9-oxo-fluorene-1-carboxylic acid, 9H-fluoren-9-one, and phthalic acid. • Tp FLU12L produced 9,10-phenanthrenedione and benzene-1,2,3-tricarboxylic acid. • Tl FLU1L initiated pathway by deoxygenating C1-C2 while Tp FLU12L C2-C3 carbon bond. [ABSTRACT FROM AUTHOR]