Carbamazepine degradation and genome sequencing of a novel exoelectrogen isolated from microbial fuel cells

Efficient degradation of carbamazepine and metagenomic investigations of anodic biofilm in microbial fuel cells

Environmental contamination with carbamazepine is a considerable global problem. In this study, two-compartment microbial fuel cells (MFCs) were constructed to investigate the degradation performance of carbamazepine, and the degradation mechanism was further explored by using metagenomic analysis. The results showed that MFCs exhibited excellent carbamazepine removal performance and also generated electricity. The removal rate of carbamazepine reached 73.56% over the 72-h operation period, which was 3.09 times higher than that of the traditional anaerobic method, and the peak voltage of the MFCs could reach 416 mV. Metagenomics revealed significant differences in microbial community composition between MFCs and the traditional anaerobic method (p < 0.05), and Proteobacteria (81.57%) was predominant bacterial phyla during the degradation of carbamazepine by MFCs. Among them, the microbial communities at the genus level were mainly composed of Pseudomonas, Pusillimonas, Burkholderia, Stenotrophomonas, Methyloversatilis and Nitrospirillum. Kyoto Encyclopedia of genes and genomes (KEGG) metabolic pathway analysis showed that the number of genes related to carbon and nitrogen metabolism increased by 85.12% and 142.25%, respectively. Importantly, a greater number of genes of microbial grown on the surface of anode were assigned to denitrification and the degradation of aromatic compounds. This research provides a cost-effective method for treating wastewater contaminated with carbamazepin.

Synergistic self-driven and heterogeneous effect of a biomass-derived urchin-like Mn3O4/C3N4 Janus micromotor catalyst for efficient degradation of carbamazepine

It is well known that obtaining efficient carbamazepine degradation materials or rapid carbamazepine-removal methods is still a challenge in the field of environmental remediation. Hence, the present study aimed to concurrently address these issues by combining a self-driven, heterostructured and low-cost biomass-templated urchin-like Janus micromotor catalyst for highly efficient carbamazepine degradation. The catalyst could autonomously move in a circle-like motion pattern via O2 bubbles generated from the Mn3O4-catalyzed decomposition of H2O2 with a velocity of 223.5 ± 7.0 μm s-1 in 1% H2O2. Benefiting from the well-structured heterojunction at the interface of C3N4 and Mn3O4, carbamazepine (CBZ) was degraded by 61% in 100 min under sunlight irradiation. In addition, density functional theory calculation results proved that the formation of the heterojunction structure promoted the generation of photo-generated carriers. Thus, the presented method provides a promising pathway for the rational construction and preparation of movable catalysts for the efficient removal of organic pollutants from wastewater.

Bio-electrochemical degradation of carbamazepine (CBZ): A comprehensive study on effectiveness, degradation pathway, and toxicological assessment

Recent attention on the detrimental effects of pharmaceutically active compounds (PhACs) in natural water has spurred researchers to develop advanced wastewater treatment methods. Carbamazepine (CBZ), a widely recognized anticonvulsant, has often been a primary focus in numerous studies due to its prevalence and resistance to breaking down. This study aims to explore the effectiveness of a bio-electrochemical system in breaking down CBZ in polluted water and to assess the potential harmful effects of the treated wastewater. The results revealed bio-electro degradation process demonstrated a collaborative effect, achieving the highest CBZ degradation compared to electrodegradation and biodegradation techniques. Notably, a maximum CBZ degradation efficiency of 92.01% was attained using the bio-electrochemical system under specific conditions: Initial CBZ concentration of 60 mg/L, pH level at 7, 0.5% (v/v) inoculum dose, and an applied potential of 10 mV. The degradation pathway established by identifying intermediate products via High-Performance Liquid Chromatography-Mass Spectrometry, revealed the complete breakdown of CBZ without any toxic intermediates or end products. This finding was further validated through in vitro and in vivo toxicity assays, confirming the absence of harmful remnants after the degradation process.

Role of microalgae-bacterial consortium in wastewater treatment: A review

In the global effort to reduce CO2 emissions, the concurrent enhancement of pollutant degradation and reductions in fossil fuel consumption are pivotal aspects of microalgae-mediated wastewater treatment. Clarifying the degradation mechanisms of bacteria and microalgae during pollutant treatment, as well as regulatory biolipid production, could enhance process sustainability. The synergistic and inhibitory relationships between microalgae and bacteria are introduced in this paper. The different stimulators that can regulate microalgal biolipid accumulation are also reviewed. Wastewater treatment technologies that utilize microalgae and bacteria in laboratories and open ponds are described to outline their application in treating heavy metal-containing wastewater, animal husbandry wastewater, pharmaceutical wastewater, and textile dye wastewater. Finally, the major requirements to scale up the cascade utilization of biomass and energy recovery are summarized to improve the development of biological wastewater treatment.

Simultaneous Wastewater Treatment and Resources Recovery by Forward Osmosis Coupled with Microbial Fuel Cell: A Review

Osmotic microbial fuel cells (OsMFCs) with the abilities to simultaneously treat wastewater, produce clean water, and electricity provided a novel approach for the application of microbial fuel cell (MFC) and forward osmosis (FO). This synergistic merging of functions significantly improved the performances of OsMFCs. Nonetheless, despite their promising potential, OsMFCs currently receive inadequate attention in wastewater treatment, water reclamation, and energy recovery. In this review, we delved into the cooperation mechanisms between the MFC and the FO. MFC facilitates the FO process by promoting water flux, reducing reverse solute flux (RSF), and degrading contaminants in the feed solution (FS). Moreover, the water flux based on the FO principle contributed to MFC's electricity generation capability. Furthermore, we summarized the potential roles of OsMFCs in resource recovery, including nutrient, energy, and water recovery, and identified the key factors, such as configurations, FO membranes, and draw solutions (DS). We prospected the practical applications of OsMFCs in the future, including their capabilities to remove emerging pollutants. Finally, we also highlighted the existing challenges in membrane fouling, system expansion, and RSF. We hope this review serves as a useful guide for the practical implementation of OsMFCs.

Recent progress in the characterization and application of exo-electrogenic microorganisms

Exo-electrogenic microorganisms are characterized by their special metabolic capability of transferring metabolic electrons out of their cell, into insoluble external electron acceptors such as iron or manganese oxides and electrodes, or vice versa take up electron from electrodes. Their conventional application is primarily limited to microbial fuel cells for electrical power generation and microbial electrolysis cells for the production of value-added products such as biohydrogen, biomethane and hydrogen peroxide. The utility of exo-electrogenic organisms has expanded into many other applications in recent times. Such examples include microbial desalination cells, microbial electro-synthesis cells producing value-added chemicals such as bio-butanol and their applications in other carbon sequestration technologies. Additionally, electrochemically-active organisms are now beginning to be employed in biosensor applications for environmental monitoring. Additionally, the utility of biocathodes in bio-electrochemical systems is also a novel application in catalyzing the cathodic oxygen reduction reaction to enhance their electrochemical performance. Advances have also been made in the expansion and use of other organisms such as the usage of photosynthetic microorganisms for the fabrication of self-sustained bio-electrochemical systems. This review attempts to provide a comprehensive picture of the state-of the art of exo-electrogenic organisms and their novel utility in bioelectrochemical systems.

Novel lanthanum-iron oxide nanoparticles alleviate the inhibition of anaerobic digestion by carbamazepine through adsorption and bioaugmentation

Several reports have shown that pharmaceuticals and personal care products (PPCPs) have some negative effects on anaerobic digestion (AD), yet there are no convenient and efficient strategies for mitigating the adverse influences. The typical PPCPs of carbamazepine have a strong negative effect on lactic acid AD process. Therefore, in this work, novel lanthanum-iron oxide (LaFeO₃) nanoparticles (NPs) were used for adsorption and bioaugmentation to weak the negative effects of carbamazepine. The adsorption removal of carbamazepine increased from 0 to 44.30% as the dosage of LaFeO₃ NPs was increased from 0 to 200 mg/L, providing the necessary prerequisites for bioaugmentation. Adsorption reduced the probability of direct contact between carbamazepine and anaerobes, partly alleviating the inhibition of carbamazepine on microbes. The highest methane (CH₄) yield induced by LaFeO₃ NPs (25 mg/L) was 226.09 mL/g lactic acid, increasing by 30.06% compared to the control yield with a recovery to 89.09% of the normal CH₄ yield. Despite the ability of LaFeO₃ NPs to restore normal AD performance, the biodegradation rate of carbamazepine remained below 10% due to its anti-biodegradability. Bioaugmentation was primarily reflected in the enhanced bioavailability of dissolved organic matter, while the intracellular LaFeO₃ NPs promoted coenzyme F420 activity through binding to humic substances. Under the mediation of LaFeO₃, a direct interspecies electron transfer system with Longilinea and Methanosaeta as functional bacteria was successfully constructed and the corresponding electron transfer rate was accelerated from 0.021 s^-1 to 0.033 s^-1. LaFeO₃ NPs eventually recovered AD performance under carbamazepine stress in an adsorption and bioaugmentation manner.

Assembled mixed co-cultures for emerging pollutant removal using native microorganisms from sewage sludge

The global pharmaceutical pollution caused by drug consumption (>100,000 tonnes) and its disposal into the environment is an issue which is currently being addressed by bioremediation techniques, using single or multiple microorganisms. Nevertheless, the low efficiency and the selection of non-compatible species interfere with the success of this methodology. This paper proposes a novel way of obtaining an effective multi-domain co-culture, with the capacity to degrade multi-pharmaceutical compounds simultaneously. To this end, seven microorganisms (fungi and bacteria) previously isolated from sewage sludge were investigated to enhance their degradation performance. All seven strains were factorially mixed and used to assemble different artificial co-cultures. Consequently, 127 artificial co-cultures were established and ranked, based on their fitness performance, by using the BSocial analysis web tool. The individual strains were categorized according to their social behaviour, whose net effect over the remaining strains was defined as 'Positive', 'Negative' or 'Neutral'. To evaluate the emerging-pollutant degradation rate, the best 10 co-cultures, and those which contained the social strains were then challenged with three different Pharmaceutical Active compounds (PhACs): diclofenac, carbamazepine and ketoprofen. The co-cultures with the fungi Penicillium oxalicum XD-3.1 and Penicillium rastrickii were able to degrade PhACs. However, the highest performance (>80% degradation) was obtained by the minimal active microbial consortia consisting of both Penicillium spp., Cladosporium cladosporoides and co-existing bacteria. These consortia transformed the PhACs to derivate molecules through hydroxylation and were released to the media, resulting in a low ecotoxicity effect. High-throughput screening of co-cultures provides a quick, reliable and efficient method to narrow down suitable degradation co-cultures for emerging PhAC contaminants while avoiding toxic metabolic derivatives.

Extracellular pollutant degradation feedback regulates intracellular electron transfer process of exoelectrogens: Strategy and mechanism

Exoelectrogens possess extraordinary degradation ability to various pollutants through extracellular electron transfer (EET). Compared with extracellular electron release process, intracellular electron transfer network is not yet fully recognized. Especially, controversy remains regarding the role of CymA, an essential electron-transfer hub of Shewanella oneidensis MR-1, in EET process. In this study, we thoroughly surveyed the intracellular transfer strategies during EET through dye decolorization. Loss of CymA severely impaired the reduction ability of S. oneidensis MR-1 to methyl orange (MO), but hardly affected the decolorization of aniline blue (AB). Complement of cymA fully restored the MO decolorization ability of ΔcymA mutant. The contribution of CymA to extracellular decolorization was subjected to MO concentrations. The defect in the decolorization ability of ΔcymA mutant was not evident at low MO concentration, but severe at high MO concentration. Further investigation revealed that EET rate determined the significance of CymA in the extracellular bioremediation by S. oneidensis MR-1. Coupled with MO concentrations increasing from 15 to 120 mg/L, the initial electron transfer rates of S. oneidensis MR-1 increased accordingly from 2.69 × 10⁴ to 11.21 × 10⁴ electrons CFU^-1 s^-1, which led to a gradual increase of the dependency_CymA. Thus, we first revealed that extracellular degradation performance could feedback regulate the intracellular electron transfer process of S. oneidensis MR-1. This work is helpful to fully understand the complex EET process of exoelectrogens and facilitates the application of exoelectrogens in bioremediation of environmental pollutants.

Photo-Induced Holes Initiating Peroxymonosulfate Oxidation for Carbamazepine Degradation via Singlet Oxygen

Peroxymonosulfate (PMS) has been intensively used to enhance the photocatalytic activity of catalysts, which is adopted as an electron acceptor to inhibit the recombination of electrons and holes. However, the effect of holes generated by visible light (VL) on PMS activation is always overlooked. Herein, the VL/Bi2WO6/PMS process was constructed for the efficient removal of organics, in which the degradation rate of carbamazepine (CBZ) increased by over 33.0 times by the introduction of PMS into Bi2WO6 under visible light. The radical quenching and determination experiments confirmed that the photogenerated holes could firstly oxidize PMS to form SO5•− and react with HSO5− to produce 1O2, then inducing the formation of other reactive species to greatly enhance the performance of pollutant removal by the VL/Bi2WO6/PMS process. Density functional theory (DFT) predicted that sites with high Fukui index (f0) on CBZ were more susceptible to being attacked, resulting in hydroxylation, ring closure, and C=C bond cleavage of CBZ. Toxicity estimation indicated that photocatalysis degradation products from CBZ were less toxic compared to the parent compound. This study provides a potential avenue for improving photocatalytic efficiency and widening the application of photocatalytic technology in wastewater purification.