Biodegradation of Endocrine Disrupting Chemicals with Laccase Isozymes from Recombinant Pichia pastori

In this paper, five recombinant strains: GS115-LacA, GS115-LacB, GS115-LacC, KM71H-Lcc1 and GS115-Lcc2 were selected to produce laccase isozymes with high activities, which reached 13,001 U/L, 10,254 U/L, 11,495 U/L, 9924 U/L and 10,031 U/L on 15th, respectively. Then, we investigated the specificity of several recombinant laccase isozymes for the degradation of endocrine disrupting chemicals (phenolic compounds). The results showed that LacB had the most efficient in degradation of bisphenol A and octyl phenol, while Lcc1 degraded 4- n -octylphenol, gossypol and hydroquinone better. Finally, the effects of degradation conditions were optimized, which shown that the degradation rates of phenolic compounds increased with the optimum temperature and pH by different laccases were different, which were closely related to their enzymatic properties. Under the optimum reaction conditions, the degradation rate of bisphenol A, gossypol, 4- n -octylphenol, octyl phenol and hydroquinone were 95.4%, 93.2%, 89.6%, 71.0% and 91.9% at 8 h, 8 h, 12 h, 24 h and 1 h, respectively. Furthermore, the recombinant laccases were used to degrade phenolic compounds in several laccase/mediator systems, which ABTS and vanillin showed most enhancement on degradation rates and reduction of degradation times. In LacB-ABTS and Lcc1-guaiacol/vanillin systems, the degradation rates of five phenolic compounds reached the maximum with totally 100% within 4 h. All of the results open up promising perspectives for the degradation and oxidative biotransformation of typical phenolic pollutants in the environment. Graphical Abstract