Removal pathway quantification and co-metabolic mechanism evaluation of alkylphenols from synthetic wastewater by phenolic root exudates in the rhizosphere of Phragmites australis

• Published in: Journal of hazardous materials 2022-02, Vol.424 (Pt A), p.127269-127269, Article 127269
• Main Authors: Zhang, Ni-Chen, Hong, Zhi-Feng, Qiu, Rong-Liang, Chao, Yuan-Qing, Yu, Ya-Fei, A, Dan
• Format: Article
• Language: English
• Subjects: Alkylphenols; Biodegradation, Environmental; Co-metabolic degradation; Enzymatic mechanism; Exudates and Transudates; Microbial response; Phenolic root exudates; Plant Roots; Poaceae; Rhizosphere; Soil Microbiology; Waste Water
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2021.127269

Phenolic root exudates (PREs) released from wetland plants are potentially effective for accelerating the biodegradation of alkylphenols, yet the inherent behavior is still unclear. In this study, two representative root exudates (REs), namely p-coumaric acid (PREs) and oxalic acid (non-PREs) were exogenously added as specific and non-specific co-metabolic substrates, respectively, to elucidate the quantification of each removal pathway and degradation mechanism of co-metabolism for alkylphenols (i.e. p-tert-butylphenol (PTBP)) from synthetic wastewater. The results showed that soil adsorption (31–37%), microbial degradation (27–37%), and plant uptake (16–41%) are the main removal pathways of PTBP by PREs in the Phragmites australis rhizosphere. Both REs enriched anaerobic functional community (anaerobic ammonium oxidation bacteria and denitrifying bacteria) and promoted the usage of PTBP as carbon source and/or electron donor. The activity of non-specific enzyme (polyphenol oxidase) was enhanced by RE which owning a significant positive correlation with bacterial abundance, whereas only PREs strengthened the activity of specific enzyme (monophenol oxidase) catalyzing the phenolic ring hydroxylation of PTBP followed by a dehydrogenation route. Moreover, exogenous PREs significantly improved the growth of degrading-related bacteria (Sphingomonas and Gemmatimonas), especially in unplanted soils with high activity of dioxygenase catalyzing the cleavage pathway of PTBP, instead of plant presence. [Display omitted] •REs promote anaerobic bacteria using PTBP as carbon source and electron donor.•REs improve the non-specific enzyme (PPO) activity for all phenolic degradation.•PREs enhance the specific enzyme (MPO) activity for hydroxylation of PTBP.•PREs enrich degrading-related bacteria of PTBP in both planted and unplanted soils.•PREs present high activity of DO in unplanted soils for cleavage pathway of PTBP.