Anaerobic phenanthrene biodegradation with four kinds of electron acceptors enriched from the same mixed inoculum and ex
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RESEARCH ARTICLE
Anaerobic phenanthrene biodegradation with four kinds of electron acceptors enriched from the same mixed inoculum and exploration of metabolic pathways Zuotao Zhang1, Chongyang Wang1,2, Jianzhong He3, Hui Wang (✉)1 1 State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China 2 Miami College, Henan University, Kaifeng 475000, China 3 Department of Civil and Environmental Engineering, National University of Singapore, Singapore 117576, Singapore
HIGHLIGHTS
GRAPHIC ABSTRACT
• Anaerobic phenanthrene biodegradation enriched process was described in detail. • The enriched bacterial communities were characterized under four redox conditions. • The enriched archaeal communities were stated under high percentage conditions. • Relatively intact pathways of anaerobic phenanthrene biodegradation were proposed.
ARTICLE INFO Article history:
Received 9 May 2019 Revised 5 September 2019 Accepted 5 September 2019 Available online 13 October 2019 Keywords: Phenanthrene Anaerobic biodegradation Bacterial populations Archaea populations Metabolic pathway
ABSTRACT Polycyclic aromatic hydrocarbons (PAHs) are widespread and persistent contaminants worldwide, especially in environments devoid of molecular oxygen. For lack of molecular oxygen, researchers enhanced anaerobic zones PAHs biodegradation by adding sulfate, bicarbonate, nitrate, and iron. However, microbial community reports of them were limited, and information of metabolites was poor except two-ring PAH, naphthalene. Here, we reported on four phenanthrene-degrading enrichment cultures with sulfate, bicarbonate, nitrate, and iron as electron acceptors from the same initial inoculum. The high-to-low order of the anaerobic phenanthrene biodegradation rate was the nitratereducing conditions>sulfate-reducing conditions>methanogenic conditions>iron-reducing conditions. The dominant bacteria populations were Desulfobacteraceae, Anaerolinaceae, and Thermodesulfobiaceae under sulfate-reducing conditions; Moraxellaceae, Clostridiaceae, and Comamonadaceae under methanogenic conditions; Rhodobacteraceae, Planococcaceae, and Xanthomonadaceae under nitrate-reducing conditions; and Geobacteraceae, Carnobacteriaceae, and Anaerolinaceae under iron-reducing conditions, respectively. Principal component analysis (PCA) indicated that bacteria populations of longtime enriched cultures with four electron acceptors all obtained significant changes from original inoculum, and bacterial communities were similar under nitrate-reducing and iron-reducing conditions. Archaea accounted for a high percentage under ironreducing and methanogenic conditions, and Methanosarcinaceae and Methanobacteriaceae, as well as Methanobacteriaceae, were the dominant archaea populations under iron-reducing and methanogenic conditions. The key steps of phenanthrene biodegradation under four reducing conditions were carboxylation, further ring system reduction, and ring cleavage. © Higher Education Press and Springer-Ve
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