- Title
- Using soil enzyme Vmax as an indicator to evaluate the ecotoxicity of lower-ring polycyclic aromatic hydrocarbons in soil: Evidence from fluorescein diacetate hydrolase kinetics
- Creator
- Li, Yan; Wang, Ziquan; Tian, Haixia; Megharaj, Mallavarapu; Jia, Hanzhong; He, Wenxiang
- Relation
- Science of The Total Environment Vol. 874, Issue 20 May 2023, no. 162521
- Publisher Link
- http://dx.doi.org/10.1016/j.scitotenv.2023.162521
- Publisher
- Elsevier
- Resource Type
- journal article
- Date
- 2023
- Description
- Fluorescein diacetate hydrolase (FDA hydrolase) is a reliable biochemical biomarker of changes in soil microbial activity and quality. However, the effect and mechanism of lower-ring polycyclic aromatic hydrocarbons (PAHs) on soil FDA hydrolase are still unclear. In this work, we investigated the effects of two typical lower-ring PAHs, naphthalene (Nap) and anthracene (Ant), on the activity and kinetic characteristics of FDA hydrolases in six soils differing in their properties. Results demonstrated that the two PAHs severely inhibited the activities of the FDA hydrolase. The values of Vmax and Km dropped by 28.72–81.24 % and 35.84–74.47 % at the highest dose of Nap, respectively, indicating an uncompetitive inhibitory mechanism. Under Ant stress, the values of Vmax decreased by 38.25–84.99 %, and the Km exhibited two forms, unchanged and decreased (74.00–91.61 %), indicating uncompetitive and noncompetitive inhibition. The inhibition constant (Ki) of the Nap and Ant ranged from 0.192 to 1.051 and 0.018 to 0.087 mM, respectively. The lower Ki of Ant compared to Nap indicated a higher affinity for enzyme-substrate complex, resulting in higher toxicity of Ant than Nap to soil FDA hydrolase. The inhibitory effect of Nap and Ant on soil FDA hydrolase was mainly affected by soil organic matter (SOM). SOM influenced the affinity of PAHs with enzyme-substrate complex, which resulted in a difference in PAHs toxicity to soil FDA hydrolase. The enzyme kinetic Vmax was a more sensitive indicator than enzyme activity to evaluate the ecological risk of PAHs. This research offers a strong theoretical foundation for quality control and risk evaluation of PAH-contaminated soils through a soil enzyme-based approach.
- Subject
- polycyclic aromatic hydrocarbons; soil Fluorescein diacetate hydrolase (FDA hydrolase); enzyme kinetics; ecotoxicological evaluation
- Identifier
- http://hdl.handle.net/1959.13/1490742
- Identifier
- uon:52970
- Identifier
- ISSN:0048-9697
- Language
- eng
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