Ligninolytic enzyme involved in removal of high molecular weight polycyclic aromatic hydrocarbons by Fusarium strain ZH-H2.

The capacity of Fusarium sp. strain ZH-H2 to secret lignin peroxidase (LiP), laccase (Lac), and manganese peroxidase (MnP) and degrade high molecular weight polycyclic aromatic hydrocarbons (HMW-PAHs) was studied. When the fungus was grown in control mineral salt medium for 4 days, LiP and Lac activities were detected at 8871 U L-1 and 5123 U L-1, respectively. In the presence of HMW-PAHs as the sole carbon source, only LiP activity was detectable, and LiP activity had significantly reduced HMW-PAHs at day 7, with a maximum decrease of 85.9%. A strong correlation between LiP activity and HMW-PAHs removal efficiency could be fit into various models, with the highest correlation coefficients obtained for quadratic functions (P < 0.01). When a specific enzyme inhibitor was added, the ability of Fusarium to remove HMW-PAHs was reduced from 85.9 to 66.7%, depending on the inhibitor's concentration. Meanwhile, the determined activity of LiP was reduced from 11.4 to 48.6%. We conclude that in the presence of HMW-PAHs as the only carbon source to support growth, Fusarium ZH-H2 mainly produces LiP but not Lac or MnP for HMW-PAHs degradation. To our knowledge, it was the first time to propose a metabolic lignin peroxidase characterization of HMW-PAHs degradation by Fusarium sp. strains.