Omics and mechanistic insights into di-(2-ethylhexyl) phthalate degradation in the O2-fluctuating estuarine sediments

Po Hsiang Wang, Yi Lung Chen, Tien Yu Wu, Yu Wei Wu, Tzi Yuan Wang, Chao Jen Shih, Sean Ting Shyang Wei, Yi Li Lai, Cheng Xuan Liu, Yin Ru Chiang

研究成果: 雜誌貢獻文章同行評審

摘要

Di-(2-ethylhexyl) phthalate (DEHP) represents the most used phthalate plasticizer with an annual production above the millions of tons worldwide. Due to its inadequate disposal, outstanding chemical stability, and extremely low solubility (3 mg/L), endocrine-disrupting DEHP often accumulates in urban estuarine sediments at concentrations above the predicted no-effect concentration (20–100 mg/kg). Our previous study suggested that microbial DEHP degradation in estuarine sediments proceeds synergistically where DEHP side-chain hydrolysis to form phthalic acid represents a bottleneck. Here, we resolved this bottleneck and deconstructed the microbial synergy in O2-fluctuating estuarine sediments. Metagenomic analysis and RNA sequencing suggested that orthologous genes encoding extracellular DEHP hydrolase NCU65476 in Acidovorax sp. strain 210-6 are often flanked by the co-expressed composite transposon and are widespread in aquatic environments worldwide. Therefore, we developed a turbidity-based microplate assay to characterize NCU65476. The optimized assay conditions (with 1 mM Ca2+ and pH 6.0) increased the DEHP hydrolysis rate by a factor of 10. Next, we isolated phthalic acid-degrading Hydrogenophaga spp. and Thauera chlorobenzoica from Guandu estuarine sediment to study the effect of O2(aq) on their metabolic synergy with strain 210-6. The results of co-culture experiments suggested that after DEHP side-chain hydrolysis by strain 210-6, phthalic acid can be degraded by Hydrogenophaga sp. when O2(aq) is above 1 mg/L or degraded by Thauera chlorobenzoica anaerobically. Altogether, our data demonstrates that DEHP could be degraded synergistically in estuarine sediments via divergent pathways responding to O2 availability. The optimized conditions for NCU65476 could facilitate the practice of DEHP bioremediation in estuarine sediments.
原文英語
文章編號134406
期刊Chemosphere
299
DOIs
出版狀態已發佈 - 7月 2022

ASJC Scopus subject areas

  • 環境工程
  • 化學 (全部)
  • 環境化學
  • 污染
  • 公共衛生、環境和職業健康
  • 健康、毒理學和誘變

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