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12 pages, 2398 KiB

Open AccessArticle

Metagenomic Insights into the Microbial Community of Activated Sludge in Oxytetracycline Wastewater Treatment

by Rui Xiao, Da Kang, Haijing Zhao, Mingze Fan, Yang Peng and Jie Niu

Water 2024, 16(24), 3680; https://doi.org/10.3390/w16243680 - 20 Dec 2024

Viewed by 1120

The overuse of antibiotics in human society poses a global health challenge, necessitating effective treatment of antibiotic production wastewater. This study examines the microbial community within activated sludge in anaerobic digestion (AD) and biological nutrient removal (BNR) systems at a full-scale oxytetracycline production wastewater treatment plant. The AD system effectively degraded polysaccharides but accumulated refractory humic-like substances, as determined by excitation–emission matrix fluorescence spectroscopy. Metagenomic analysis revealed distinct microbial communities between the AD and BNR systems, with Bacteroides (13.9%) and Proteiniphilum (33.5%) as the most abundant genus in the AD and BNR systems, respectively. Functional gene analysis showed a high presence of carbohydrate binding and glycoside hydrolases. The low abundance of nitrite oxidizer and the nxr gene might explain nitrite accumulation in the BNR system via partial nitrification. The antibiotic resistance genes (ARGs) affiliated with tetracycline were dominant in both the AD and BNR systems, with 45% of tetracycline and 20% of total ARGs being efficiently removed during the anaerobic treatment. The findings of this study can provide insights into microbial response to oxytetracycline production wastewater, informing the optimization of biological treatment processes and mitigating the environmental impacts of antibiotic production. Full article

(This article belongs to the Section Wastewater Treatment and Reuse)

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22 pages, 8111 KiB

Open AccessArticle

Evaluation of Antibiotic Biodegradation by a Versatile and Highly Active Recombinant Laccase from the Thermoalkaliphilic Bacterium Bacillus sp. FNT

by Jorge Sánchez-SanMartín, Sebastián L. Márquez, Giannina Espina, Rodrigo Cortés-Antiquera, Junsong Sun and Jenny M. Blamey

Biomolecules 2024, 14(3), 369; https://doi.org/10.3390/biom14030369 - 19 Mar 2024

Cited by 3 | Viewed by 2941

Abstract

Laccases are industrially relevant enzymes that have gained great biotechnological importance. To date, most are of fungal and mesophilic origin; however, enzymes from extremophiles possess an even greater potential to withstand industrial conditions. In this study, we evaluate the potential of a recombinant spore-coat laccase from the thermoalkaliphilic bacterium Bacillus sp. FNT (FNTL) to biodegrade antibiotics from the tetracycline, β-lactams, and fluoroquinolone families. This extremozyme was previously characterized as being thermostable and highly active in a wide range of temperatures (20–90 °C) and very versatile towards several structurally different substrates, including recalcitrant environmental pollutants such as PAHs and synthetic dyes. First, molecular docking analyses were employed for initial ligand affinity screening in the modeled active site of FNTL. Then, the in silico findings were experimentally tested with four highly consumed antibiotics, representatives of each family: tetracycline, oxytetracycline, amoxicillin, and ciprofloxacin. HPLC results indicate that FNTL with help of the natural redox mediator acetosyringone, can efficiently biodegrade 91, 90, and 82% of tetracycline (0.5 mg mL⁻¹) in 24 h at 40, 30, and 20 °C, respectively, with no apparent ecotoxicity of the products on E. coli and B. subtilis. These results complement our previous studies, highlighting the potential of this extremozyme for application in wastewater bioremediation. Full article

(This article belongs to the Special Issue Recent Advances in Laccases and Laccase-Based Bioproducts)

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19 pages, 7212 KiB

Open AccessArticle

The Degradation of Aqueous Oxytetracycline by an O₃/CaO₂ System in the Presence of

{HCO}_{3}^{-}

: Performance, Mechanism, Degradation Pathways, and Toxicity Evaluation

by Zedian Li, Liangrui Xiang, Shijia Pan, Dahai Zhu, Shen Li and He Guo

Molecules 2024, 29(3), 659; https://doi.org/10.3390/molecules29030659 - 31 Jan 2024

Cited by 5 | Viewed by 1659

Abstract

This research constructed a novel O₃/CaO₂/

{HCO}_{3}^{-}

system to degrade antibiotic oxytetracycline (OTC) in water. The results indicated that CaO₂ and

{HCO}_{3}^{-}

addition could promote OTC degradation in an O₃ system. There is [...] Read more.

This research constructed a novel O₃/CaO₂/

{HCO}_{3}^{-}

system to degrade antibiotic oxytetracycline (OTC) in water. The results indicated that CaO₂ and

{HCO}_{3}^{-}

addition could promote OTC degradation in an O₃ system. There is an optimal dosage of CaO₂ (0.05 g/L) and

{HCO}_{3}^{-}

(2.25 mmol/L) that promotes OTC degradation. After 30 min of treatment, approximately 91.5% of the OTC molecules were eliminated in the O₃/CaO₂/

{HCO}_{3}^{-}

system. A higher O₃ concentration, alkaline condition, and lower OTC concentration were conducive to OTC decomposition. Active substances including ·OH, ¹O₂,

\cdot O_{2}^{-}

, and ·

{HCO}_{3}^{-}

play certain roles in OTC degradation. The production of ·OH followed the order: O₃/CaO₂/

{HCO}_{3}^{-}

> O₃/CaO₂ > O₃. Compared to the sole O₃ system, TOC and COD were easier to remove in the O₃/CaO₂/

{HCO}_{3}^{-}

system. Based on DFT and LC-MS, active species dominant in the degradation pathways of OTC were proposed. Then, an evaluation of the toxic changes in intermediates during OTC degradation was carried out. The feasibility of O₃/CaO₂/

{HCO}_{3}^{-}

for the treatment of other substances, such as bisphenol A, tetracycline, and actual wastewater, was investigated. Finally, the energy efficiency of the O₃/CaO₂/

{HCO}_{3}^{-}

system was calculated and compared with other mainstream processes of OTC degradation. The O₃/CaO₂/

{HCO}_{3}^{-}

system may be considered as an efficient and economical approach for antibiotic destruction. Full article

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47 pages, 6925 KiB

Open AccessFeature PaperReview

Review on Recent Advances in the Removal of Organic Drugs by Advanced Oxidation Processes

by Muhammad Umair, Tayyaba Kanwal, Vittorio Loddo, Leonardo Palmisano and Marianna Bellardita

Catalysts 2023, 13(11), 1440; https://doi.org/10.3390/catal13111440 - 14 Nov 2023

Cited by 13 | Viewed by 3850

Abstract

In recent years, due to the high consumption of drugs both for human needs and for their growing use, especially as regards antibiotics, in the diet of livestock, water pollution has reached very high levels and attracted widespread attention. Drugs have a stable chemical structure and are recalcitrant to many treatments, especially biological ones. Among the methods that have shown high efficiency are advanced oxidation processes (AOPs) which are, among other things, inexpensive and eco-friendly. AOPs are based on the production of reactive oxygen species (ROS) able to degrade organic pollutants in wastewater. The main problem related to the degradation of drugs is their partial oxidation to compounds that are often more harmful than their precursors. In this review, which is not intended to be exhaustive, we provide an overview of recent advances in the removal of organic drugs via advanced oxidation processes (AOPs). The salient points of each process, highlighting advantages and disadvantages, have been summarized. In particular, the use of AOPs such as UV, ozone, Fenton-based AOPs and heterogeneous photocatalysis in the removal of some of the most common drugs (tetracycline, ibuprofen, oxytetracycline, lincomycin) has been reported. Full article

(This article belongs to the Special Issue Environmental Catalysis in Advanced Oxidation Processes, 2nd Edition)

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11 pages, 3261 KiB

Open AccessArticle

Efficient Degradation of Tetracycline Antibiotics by Engineered Myoglobin with High Peroxidase Activity

by Guang-Rong Wu, Li-Juan Sun, Jia-Kun Xu, Shu-Qin Gao, Xiang-Shi Tan and Ying-Wu Lin

Molecules 2022, 27(24), 8660; https://doi.org/10.3390/molecules27248660 - 7 Dec 2022

Cited by 19 | Viewed by 3673

Abstract

Tetracyclines are one class of widely used antibiotics. Meanwhile, due to abuse and improper disposal, they are often detected in wastewater, which causes a series of environmental problems and poses a threat to human health and safety. As an efficient and environmentally friendly method, enzymatic catalysis has attracted much attention. In previous studies, we have designed an efficient peroxidase (F43Y/P88W/F138W Mb, termed YWW Mb) based on the protein scaffold of myoglobin (Mb), an O₂ carrier, by modifying the heme active center and introducing two Trp residues. In this study, we further applied it to degrade the tetracycline antibiotics. Both UV-Vis and HPLC studies showed that the triple mutant YWW Mb was able to catalyze the degradation of tetracycline, oxytetracycline, doxycycline, and chlortetracycline effectively, with a degradation rate of ~100%, ~98%, ~94%, and ~90%, respectively, within 5 min by using H₂O₂ as an oxidant. These activities are much higher than those of wild-type Mb and other heme enzymes such as manganese peroxidase. As further analyzed by UPLC-ESI-MS, we identified multiple degradation products and thus proposed possible degradation mechanisms. In addition, the toxicity of the products was analyzed by using in vitro antibacterial experiments of E. coli. Therefore, this study indicates that the engineered heme enzyme has potential applications for environmental remediation by degradation of tetracycline antibiotics. Full article

(This article belongs to the Special Issue Latest Discoveries in Metalloproteins)

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