Co-metabolic enzymes and pathways of 3-phenoxybenzoic acid degradation by Aspergillus oryzae M-4

• Published in: Ecotoxicology and environmental safety 2020-02, Vol.189, p.109953, Article 109953
• Main Authors: Zhao, Jiayuan, Jia, Dongying, Chi, Yuanlong, Yao, Kai
• Format: Article
• Language: English
• Subjects: 3-Phenoxybenzoic acid; Alkenes - metabolism; Aspergillus oryzae - enzymology; Aspergillus oryzae M-4; Benzoates - metabolism; Biodegradation; Catechols - metabolism; Co-metabolic enzymes; Gallic Acid - metabolism; Peroxidases - metabolism; Phenol - metabolism; Pyrethroids
• ISSN: 0147-6513; 1090-2414
• DOI: 10.1016/j.ecoenv.2019.109953

As an intermediate metabolite of pyrethroids, 3-phenoxybenzoic acid (3-PBA) is more toxic than its parent compounds and has been detected in milk, soil, and human urine. 3-PBA can be metabolized through microbial degradation, but the microbial co-metabolic enzymes and pathways involved in 3-PBA degradation are unclear. This study investigated the enzymes types and possible pathways in the co-metabolic degradation of 3-PBA by Aspergillus oryzae M-4. The enzymes involved in co-metabolic degradation of 3-PBA and its intermediate metabolites were induced, and existed extracellularly and intracellularly except the catechol-degrading enzyme. Inhibitors and inducers of these oxidases were used to examine the enzymes required for co-metabolic degradation of 3-PBA and its intermediate metabolites. 3-PBA is hydroxylated to produce 3-hydroxy-5-phenoxy benzoic acid through the catalytic actions of lignin peroxidase (LiP). Phenol and gallic acid, the metabolites of 3-PBA, are produced via cleavage of an ether bond under the catalytic actions of cytochrome P450 (CYP450) and LiP. Phenol can be converted to catechol by LiP; catechol and gallic acid are cleaved to form long-chain olefin acid or olefin aldehyde by dioxygenase and LiP. In corn flour, some of these enzyme activators such as FeCl3, 4-cumaric acid, veratryl alcohol and sodium periodate appeared to improve 3-PBA degradation. The results provide a reliable pathway and characteristics for co-metabolic microbial degradation of 3-PBA in food and the environment. [Display omitted] •Co-metabolic enzymes of 3-PBA and its intermediate metabolites were investigated.•Co-metabolic pathways of 3-PBA degradation are being elaborated.•CYP450, LiP, laccase, and dioxygenase mediated 3-PBA degradation.•Substrate regulation could help strain M-4 degrade 3-PBA completely in corn flour.