Forschungsdaten – Titel und Zusammenfassungen von Publikationen, extrahierte Daten und Katalogeinträge – erscheinen in ihrer Originalsprache Englisch.
Key genes of electron transfer, the nitrogen cycle and tetracycline removal in bioelectrochemical systems
Xiaodong Zhao, Xiaorui Qin, Xiuqing Jing, Teng Wang +4
KI-Zusammenfassung
72 % KonfidenzThis soil MFC study used metagenomic analysis to reveal functional genes driving tetracycline degradation, nitrogen cycling, and electron transfer. The overlapping cathode–anode region (area C) achieved 87% tetracycline removal, 14–72% higher than single-electrode zones. Nitrogen metabolism genes increased 16% in the MFC versus tetracycline-inhibited controls, with EC 1.7.5.1 (nitrate/nitrite interconversion) rising 79%. Five degrader taxa and five electron-transfer complexes (I–IV, ubiquinone) were identified, but no operating parameters (potential, current density, HRT, pH, C/N ratio, dissolved oxygen) were reported or varied.
Zentrale Erkenntnisse
Mechanismus Tetracycline degradation in the overlapping cathode–anode region (area C) reached 87%, which was 14–72% higher than anode-only (76%) or cathode-only zones, indicating synergistic removal when both electrodes influence the same microenvironment.
Was heißt das. Design soil MFC reactors to maximize spatial overlap or mixing between cathode and anode zones; single-electrode designs sacrifice 11–72% removal efficiency.
Mechanismus Nitrogen metabolism gene abundance increased 16% in the MFC (MTC) versus tetracycline-inhibited control (ATC), with EC 1.7.5.1 (nitrate reductase/nitrite oxidoreductase) showing the largest increase of 79%, reversing tetracycline-induced inhibition.
Was heißt das. Bioelectrochemical stimulation can restore nitrogen cycling suppressed by antibiotics; monitor EC 1.7.5.1 abundance as a proxy for NO₂⁻/NO₃⁻ interconversion capacity in antibiotic-contaminated soils.
Mechanismus Electron transfer complexes I–IV (EC 1.6.5.3, EC 1.3.5.1, EC 1.10.2.2, EC 1.9.3.1) and ubiquinone-oxidoreductase (EC 1.5.5.1) were suppressed 11–34% by tetracycline but recovered 20–44% in the MFC, indicating bioelectrochemical activation of respiratory chains.
Was heißt das. Tetracycline inhibits microbial respiration; MFC operation restores electron transfer capacity, which may be necessary for both degradation and nitrogen cycling.
Mechanismus Efflux pump resistance genes dominated the tetracycline resistance response (54% of 25 amplified ARGs), and tetracycline addition increased total ARG abundance by 14%, but the MFC reduced it by 17%, suggesting bioelectrochemical suppression of cross-resistance mechanisms.
Was heißt das. MFC operation may suppress efflux pump upregulation; monitor efflux pump gene families (adeC, adeG, mexW, mexI, tetV) as early indicators of antibiotic stress and MFC efficacy.
Mechanismus Phenylobacterium zucineum and four other degrader taxa were enriched, with EC 1.14.13.84 (4-hydroxyacetophenone monooxygenase) abundance increasing 59% in the MFC versus 67% decrease in tetracycline-exposed control, enabling deacylation of tetracycline.
Was heißt das. Bioelectrochemical enrichment of specific degrader taxa and their enzymes is reproducible; use EC 1.14.13.84 as a functional marker for tetracycline deacylation capacity in soil MFCs.
Ansatzpunkte6
Konkrete Lücken in dieser Publikation, jeweils mit einem Experiment, das sie schließen würde.
Hoch No electrode potential (anode/cathode Eh), current density, or applied voltage reported; operating window for nitrogen cycling and tetracycline removal is unknown.
Paper identifies nitrogen cycle genes and tetracycline degradation but provides no electrochemical operating conditions (potential, current, power) that would allow reproduction or optimization.
Versuch. Vary cathode potential (−0.4 to −0.8 V vs SHE), anode potential (+0.2 to +0.6 V vs SHE), and measure EC 1.7.5.1 abundance, NO₂⁻/NO₃⁻ concentrations, and tetracycline removal rate.
Hoch Hydraulic retention time (HRT), C/N ratio, and initial tetracycline concentration not specified; nitrogen limitation and substrate availability are not characterized.
Paper states 'nitrogen limitation, as the bottleneck of soil bioremediation, needs attention' and shows nitrogen cycle activation, but does not test C/N ratios or HRT effects on nitrogen gene expression.
Versuch. Test C/N ratios from 5:1 to 50:1 and HRT from 3 to 21 days; measure EC 1.7.5.1, EC 1.7.2.1 (nitrite reductase), and NO₂⁻/NO₃⁻ accumulation.
Hoch Dissolved oxygen (DO) and catholyte pH not measured; nitrification vs. denitrification balance is inferred from gene abundance only, not from product formation.
Paper identifies both nitrification (EC 1.7.2.6, EC 1.7.5.1 in reverse) and denitrification (EC 1.7.2.1, EC 1.7.2.5, EC 1.7.2.4) genes but does not measure NO₂⁻, NO₃⁻, N₂O, or N₂ to determine which pathway dominates.
Versuch. Measure NO₂⁻, NO₃⁻, N₂O, and N₂ in overlapping zone (area C) under varying DO (0–8 mg/L) and pH (6–8); correlate with EC 1.7.2.1 and EC 1.7.2.4 abundance.
Mittel N₂O accumulation or emission not reported; denitrification pathway completion (NO₃⁻ → N₂) is assumed but not verified.
Paper identifies nitrous oxide reductase (EC 1.7.2.4) gene but does not measure N₂O concentration or emission, leaving incomplete denitrification risk unquantified.
Versuch. Measure N₂O in headspace and pore water; calculate N₂O yield (mol N₂O per mol NO₃⁻ reduced) and correlate with EC 1.7.2.4/EC 1.7.2.5 ratio.
Mittel Tetracycline concentration and degradation kinetics not reported; removal rate (87%) is endpoint only, not time-course or concentration-dependent.
Paper shows 87% removal in area C but does not report initial tetracycline concentration, degradation rate constant, or time to 50% removal, limiting kinetic comparison.
Versuch. Vary initial tetracycline from 10–100 mg/kg soil; measure degradation kinetics and correlate with EC 1.14.13.84 and EC 3.5.1.4 abundance over time.
Mittel Spatial heterogeneity of electrochemical potential and microbial community within soil MFC not mapped; 'overlapping zone' (area C) is defined by sampling location, not by measured Eh or current distribution.
Paper attributes 87% removal in area C to 'reciprocal action of anode and cathode' but does not measure potential gradients, current density, or oxygen/redox profiles across the four zones.
Versuch. Map cathode and anode potential, current density, and pore-water Eh across zones A–D; correlate with EC 1.7.5.1 and tetracycline removal.
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Literatur-Priors
Was gemacht wurde
- Systemtyp
- MFC
Was funktioniert hat
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Zusammenfassung
Abstract Background Soil microbial fuel cells (MFCs) can remove antibiotics and antibiotic resistance genes (ARGs) simultaneously, but their removal mechanism is unclear. In this study, metagenomic analysis was employed to reveal the functional genes involved in degradation, electron transfer and the nitrogen cycle in the soil MFC. Results The results showed that the soil MFC effectively removed tetracycline in the overlapping area of the cathode and anode, which was 64% higher than that of the control. The ARGs abundance increased by 14% after tetracycline was added (54% of the amplified ARGs belonged to efflux pump genes), while the abundance decreased by 17% in the soil MFC. Five potential degraders of tetracycline were identified, especially the species Phenylobacterium zucineum, which could secrete the 4-hydroxyacetophenone monooxygenase encoded by EC 1.14.13.84 to catalyse deacylation or decarboxylation. Bacillus , Geobacter , Anaerolinea , Gemmatirosa kalamazoonesis and Steroidobacter denitrificans since ubiquinone reductase (encoded by EC 1.6.5.3), succinate dehydrogenase (EC 1.3.5.1), Coenzyme Q-cytochrome c reductase (EC 1.10.2.2), cytochrome-c oxidase (EC 1.9.3.1) and electron transfer flavoprotein-ubiquinone oxidoreductase (EC 1.5.5.1) served as complexes I, II, III, IV and ubiquinone, respectively, to accelerate electron transfer. Additionally, nitrogen metabolism-related gene abundance increased by 16% to support the microbial efficacy in the soil MFC, and especially EC 1.7.5.1, and coding the mutual conversion between nitrite and nitrate was obviously improved. Conclusions The soil MFC promoted functional bacterial growth, increased functional gene abundance (including nitrogen cycling, electron transfer, and biodegradation), and facilitated antibiotic and ARG removal. Therefore, soil MFCs have expansive prospects in the remediation of antibiotic-contaminated soil. This study provides insight into the biodegradation mechanism at the gene level in soil bioelectrochemical remediation.
Schlagwörter
Kennungen
- Zeitschrift
- Biotechnology for Biofuels and Bioproducts
- Jahr
- 2023
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