Biochar affects the dissipation of antibiotics and abundance of antibiotic resistance genes in pig manure

Impact of residual antibiotics on microbial decomposition of livestock manures in Eutric Regosol: Implications for sustainable nutrient recycling and soil carbon sequestration

The land application of livestock manure has been widely acknowledged as a beneficial approach for nutrient recycling and environmental protection. However, the impact of residual antibiotics, a common contaminant of manure, on the degradation of organic compounds and nutrient release in Eutric Regosol is not well understood. Here, we studied, how oxytetracycline (OTC) and ciprofloxacin (CIP) affect the decomposition, microbial community structure, extracellular enzyme activities and nutrient release from cattle and pig manure using litterbag incubation experiments. Results showed that OTC and CIP greatly inhibited livestock manure decomposition, causing a decreased rate of carbon (28%-87%), nitrogen (15%-44%) and phosphorus (26%-43%) release. The relative abundance of gram-negative (G-) bacteria was reduced by 4.0%-13% while fungi increased by 7.0%-71% during a 28-day incubation period. Co-occurrence network analysis showed that antibiotic exposure disrupted microbial interactions, particularly among G- bacteria, G+ bacteria, and actinomycetes. These changes in microbial community structure and function resulted in decreased activity of urease, β-1,4-N-acetyl-glucosaminidase, alkaline protease, chitinase, and catalase, causing reduced decomposition and nutrient release in cattle and pig manures. These findings advance our understanding of decomposition and nutrient recycling from manure-contaminated antibiotics, which will help facilitate sustainable agricultural production and soil carbon sequestration.

A comprehensive review of antibiotic resistance gene contamination in agriculture: Challenges and AI-driven solutions

Since their discovery, the prolonged and widespread use of antibiotics in veterinary and agricultural production has led to numerous problems, particularly the emergence and spread of antibiotic-resistant bacteria (ARB). In addition, other anthropogenic factors accelerate the horizontal transfer of antibiotic resistance genes (ARGs) and amplify their impact. In agricultural environments, animals, manure, and wastewater are the vectors of ARGs that facilitate their spread to the environment and humans via animal products, water, and other environmental pathways. Therefore, this review comprehensively analyzed the current status, removal methods, and future directions of ARGs on farms. This article 1) investigates the origins of ARGs on farms, the pathways and mechanisms of their spread to surrounding environments, and various strategies to mitigate their spread; 2) determines the multiple factors influencing the abundance of ARGs on farms, the pathways through which ARGs spread from farms to the environment, and the effects and mechanisms of non-antibiotic factors on the spread of ARGs; 3) explores methods for controlling ARGs in farm wastes; and 4) provides a comprehensive summary and integration of research across various fields, proposing that in modern smart farms, emerging technologies can be integrated through artificial intelligence to control or even eliminate ARGs. Moreover, challenges and future research directions for controlling ARGs on farms are suggested.

Biofilm enhanced the mitigations of antibiotics and resistome in sulfadiazine and trimethoprim co-contaminated soils

Reducing antibiotic levels in soil ecosystems is vital to curb the dissemination of antimicrobial resistance genes (ARGs) and mitigate global health threats. However, gaps persist in understanding how antibiotic resistome can be suppressed during antibiotic degradation. Herein, we investigate the efficacy of a biochar biofilm incorporating antibiotics-degrading bacterial strain (Arthrobacter sp. D2) to mitigate antibiotic resistome in non-manured and manure-amended soils with sulfadiazine (SDZ) and trimethoprim (TMP) contamination. Results show that biofilm enhanced SDZ degradation by 83.0% within three days and increased TMP attenuation by 55.4% over 60 days in non-manured soils. In the non-manured black soil, the relative abundance of ARGs increased initially after biofilm inoculation. However, by day 30, it decreased by 20.5% compared to the controls. Moreover, after 7 days, biofilm reduced TMP by 38.5% in manured soils and decreased the total ARG abundance by 19.0%. Thus, while SDZ degradation did not increase sulfonamide resistance genes, TMP dissipation led to a proliferation of insertion sequences and related TMP resistance genes. This study underscores the importance of antibiotic degradation in reducing related ARGs while cautioning against the potential proliferation and various ARGs transfer by resistant microorganisms.

Multiomics analysis of the effects of manure-borne doxycycline combined with oversized fiber microplastics on pak choi growth and the risk of antibiotic resistance gene transmission

In this study, oversized microplastics (OMPs) were intentionally introduced into soil containing manure-borne doxycycline (DOX). This strategic approach was used to systematically examine the effects of combined OMP and DOX pollution on the growth of pak choi, analyze alterations in soil environmental metabolites, and explore the potential migration of antibiotic resistance genes (ARGs). The results revealed a more pronounced impact of DOX than of OMPs. Slender-fiber OMPs (SF OMPs) had a more substantial influence on the growth of pak choi than did coarse-fiber OMPs (CF OMPs). Conversely, CF OMPs had a more significant effect on the migration of ARGs within the system. When DOX was combined with OMPs, the negative effects of DOX on pak choi growth were mitigated through the synthesis of indole through the adjustment of carbon metabolism and amino acid metabolism in pak choi roots. In this process, Pseudohongiellaceae and Xanthomonadaceae were key bacteria. During the migration of ARGs, the potential host bacterium Limnobacter should be considered. Additionally, the majority of potential host bacteria in the pak choi endophytic environment were associated with tetG. This study provides insights into the intricate interplay among DOX, OMPs, ARGs, plant growth, soil metabolism, and the microbiome.

From wastewater to clean water: Recent advances on the removal of metronidazole, ciprofloxacin, and sulfamethoxazole antibiotics from water through adsorption and advanced oxidation processes (AOPs)

Antibiotics released into water sources pose significant risks to both human health and the environment. This comprehensive review meticulously examines the ecotoxicological impacts of three prevalent antibiotics-ciprofloxacin, metronidazole, and sulfamethoxazole-on the ecosystems. Within this framework, our primary focus revolves around the key remediation technologies: adsorption and advanced oxidation processes (AOPs). In this context, an array of adsorbents is explored, spanning diverse classes such as biomass-derived biosorbents, graphene-based adsorbents, MXene-based adsorbents, silica gels, carbon nanotubes, carbon-based adsorbents, metal-organic frameworks (MOFs), carbon nanofibers, biochar, metal oxides, and nanocomposites. On the flip side, the review meticulously examines the main AOPs widely employed in water treatment. This includes a thorough analysis of ozonation (O3), the photo-Fenton process, UV/hydrogen peroxide (UV/H2O2), TiO2 photocatalysis, ozone/UV (O3/UV), radiation-induced AOPs, and sonolysis. Furthermore, the review provides in-depth insights into equilibrium isotherm and kinetic models as well as prospects and challenges inherent in these cutting-edge processes. By doing so, this review aims to empower readers with a profound understanding, enabling them to determine research gaps and pioneer innovative treatment methodologies for water contaminated with antibiotics.

Antibiotic resistance genes fate during food waste management - Comparison between thermal treatment, hyperthermophilic composting, and anaerobic membrane bioreactor

The fate of eight different antibiotic resistance genes (ARGs) in food waste (sul1, sul2, tetO, tetW, ermF, ermB, ampC, oxa-1), intI1, and rpoB were monitored during thermal treatment (pyrolysis and incineration), hyperthermophilic composting, and anaerobic membrane bioreactor (AnMBR) treatment. ARGs in food waste ranged from 2.9 × 106 to 3.5 × 109 copies/kg with ampC being the least abundant and sul1 being the most abundant. Thermal treatment achieved removal below detection limits of all ARGs. Only two ARGs (sul1 and ampC) persisted in hyperthermophilic composting. While all genes except for ermB decreased in the AnMBR effluent relative to the food waste feed, sul1 remained at relatively high abundance. Biosolids on the contrary, accumulated tetO, ampC and sul2 in all tested operating conditions. Thermal treatment, despite limited resource recovery, provides the most effective mitigation of ARG risk in food waste.

Influence of Manure as a Complex Mixture on Soil Sorption of Pharmaceuticals-Studies with Selected Chemical Components of Manure

Pharmaceutically active compounds (PhACs) enter soil with organic waste materials such as manure. Such complex substrates differently affect PhACs' soil sorption. For the first time, batch experiments were conducted using five selected chemicals as model constituents to elucidate the effects. Urea, phosphate (KH₂PO₄), acetic acid, phenol and nonadecanoic acid (C:19) altered the sorption strength and/or nonlinearity of sulfadiazine, caffeine, and atenolol in an arable Cambisol topsoil. The nonlinear Freundlich model best described sorption. Overall, the PhACs' Freundlich coefficients (sorption strength) increased in the sequence urea < phosphate < phenol < C:19 < acetic acid, while the Freundlich exponents largely decreased, indicating increasing sorption specificity. The effects on sulfadiazine and caffeine were rather similar, but in many cases different from atenolol. Phosphate mobilized sulfadiazine and caffeine and urea mobilized sulfadiazine, which was explained by sorption competition resulting from specific preference of similar sorption sites. Soil sorbed phenol strongly increased the sorption of all three PhACs; phenolic functional groups are preferred sorption sites of PhACs in soil. The large increase in sorption of all PhACs by acetic acid was attributed to a loosening of the soil organic matter and thus the creation of additional sorption sites. The effect of C:19 fatty acid, however, was inconsistent. These results help to better understand the sorption of PhACs in soil-manure mixtures.

Occurrence of antibiotics in wastewater: Potential ecological risk and removal through anaerobic-aerobic systems

Antibiotics are intensively used to improve public health, prevent diseases and enhance productivity in animal farms. Contrarily, when released, the antibiotics laden wastewater produced from pharmaceutical industries and their application sources poses a potential ecological risk to the environment. This study provides a discussion on the occurrence of various antibiotics in wastewater and their potential ecological risk in the environment. Further, a critical review of anaerobic-aerobic processes based on three major systems (such as constructed wetland, high-rate bioreactor, and integrated treatment technologies) applied for antibiotics removal from wastewater is performed. The review also explores microbial dynamics responsible for antibiotic biodegradation in anaerobic-aerobic systems and its economic feasibility at wider-scale applications. The operational problems and prospective modifications are discussed to define key future research directions. The appropriate selection of treatment processes, sources control, understanding of antibiotic fate, and adopting precise monitoring strategies could eliminate the potential ecological risks of antibiotics. Integrated bio-electrochemical systems exhibit antibiotics removal ≥95% by dominant Geobacter sp. at short HRT ∼4-10 h. Major process factors like organic loading rate, hydraulic loading rate (HRT), and solid retention time significantly affect the system performance. This review will be beneficial to the researchers by providing in-depth understanding of antibiotic pollution and its abatement via anaerobic-aerobic processes to develop sustainable wastewater treatment technology in the future.

Effect of sulfamethazine on the horizontal transfer of plasmid-mediated antibiotic resistance genes and its mechanism of action

As a new type of environmental pollutant, antibiotic resistance genes (ARGs) pose a huge challenge to global health. Horizontal gene transfer (HGT) represents an important route for the spread of ARGs. The widespread use of sulfamethazine (SM2) as a broad-spectrum bacteriostatic agent leads to high residual levels in the environment, thereby increasing the spread of ARGs. Therefore, we chose to study the effect of SM2 on the HGT of ARGs mediated by plasmid RP4 from Escherichia coli (E. coli) HB101 to E. coli NK5449 as well as its mechanism of action. The results showed that compared with the control group, SM2 at concentrations of 10 mg/L and 200 mg/L promoted the HGT of ARGs, but transfer frequency decreased at concentrations of 100 mg/L and 500 mg/L. The transfer frequency at 200 mg/L was 3.04 × 10^-5, which was 1.34-fold of the control group. The mechanism of SM2 improving conjugation transfer is via enhancement of the mRNA expression of conjugation genes (trbBP, trfAP) and oxidative stress genes, inhibition of the mRNA expression of vertical transfer genes, up regulation of the outer membrane protein genes (ompC, ompA), promotion of the formation of cell pores, and improvement of the permeability of cell membrane to promote the conjugation transfer of plasmid RP4. The results of this study provide theoretical support for studying the spread of ARGs in the environment.

A review of the impact of conductive materials on antibiotic resistance genes during the anaerobic digestion of sewage sludge and animal manure

The urgent need to reduce the environmental burden of antibiotic resistance genes (ARGs) has become even more apparent as concerted efforts are made globally to tackle the dissemination of antimicrobial resistance. Concerning levels of ARGs abound in sewage sludge and animal manure, and their inadequate attenuation during conventional anaerobic digestion (AD) compromises the safety of the digestate, a nutrient-rich by-product of AD commonly recycled to agricultural land for improvement of soil quality. Exogenous ARGs introduced into the natural environment via the land application of digestate can be transferred from innocuous environmental bacteria to clinically relevant bacteria by horizontal gene transfer (HGT) and may eventually reach humans through food, water, and air. This review, therefore, discusses the prospects of using carbon- and iron-based conductive materials (CMs) as additives to mitigate the proliferation of ARGs during the AD of sewage sludge and animal manure. The review spotlights the core mechanisms underpinning the influence of CMs on the resistome profile, the steps to maximize ARG attenuation using CMs, and the current knowledge gaps. Data and information gathered indicate that CMs can profoundly reduce the abundance of ARGs in the digestate by easing selective pressure on ARGs, altering microbial community structure, and diminishing HGT.

Occurrence and prevalence of antibiotic resistance genes in apple orchard after continual application of anaerobic fermentation residues of pig manure

Fermented organic fertilizers made from pig manure contaminated with antibiotics are widely used in fruit tree production. However, their effects on the residual antibiotics and the spread of antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) in apple orchards are still largely unknown. In the present study, we detected 100 ARGs and 10 MGEs that were transferred from pig manure to an apple orchard. Compared with the original pig manure, significantly greater concentrations of tetracycline, chlortetracycline, oxytetracycline, sulfadiazine, and salfamethyldiazine were observed in anaerobic fermentation residues of the pig manure. The total relative abundance levels of ARGs on the apple pericarp surface, in the orchard soil treated with biogas slurry, and in the orchard soil treated with biogas residue were 122.5, 5.2, 1.4 times higher than those in pristine soil, respectively, which were primarily attributed to the increase in the relative abundance of some ARG subtypes, including blaCTX-M, blaTEM, ermC, sul2, tetO, vgaB, and vgb. Long-term biogas slurry and biogas residue applications to orchard soil enriched bioaccumulation of 10 ARGs and 1 MGEs on the apple pericarp surface with 67.98 the highest factor. This research indicates that the application of anaerobic fermentation residues of pig manure promoted the spread of ARGs in the soil and fruits and increased the level of ARG pollution in the orchard. Results of this study highlight the importance of assessing the ecological safety of organic fertilizers from the perspective of ARGs and indicate that efforts should be devoted to further reducing ARG levels in pig manure before its application to farmland.

Manure and biochar have limited effect on lettuce leaf endophyte resistome

Soil amendment with manure compost and biochar is widely adopted to improve soil fertility and promote plant growth, and their effects on soil microbial communities and resistome have been well documented. However, there is sparse information regarding their effects on vegetable endophytes, which represent a major source of human exposure to pathogens and antibiotic resistance genes (ARGs) when eaten raw. Here, we investigated the impacts of manure compost or biochar addition on the bacterial community compositions and ARGs in the soil-lettuce continuum including soil, seed, leaf, and root samples. A total of 137 ARGs and 31 mobile genetic elements (MGEs) were detected in all the samples after 60 days of cultivation. The relative abundance of ARGs and the diversity of bacteria communities presented a consistent decreasing trend from soil to root endophytes, then leaf endophytes. Manure compost addition increased the diversity and abundance of ARGs in soil, while significant changes in the ARG profiles and bacterial communities were not observed in leaf endophytes after manure compost or biochar addition, or both. Bipartite networks analysis suggested that seed microbiome was one of the major sources of plant endophytes and ARGs. Twenty potential human pathogens were isolated from lettuce, indicating potential exposure risk to pathogens via the consumption of raw lettuce. These results suggest limited impacts of manure compost and biochar addition on lettuce endophytes and highlight the contribution of seed microbiome to endophyte ARG profiles.

A review of antibiotics and antibiotic resistance genes (ARGs) adsorption by biochar and modified biochar in water

Antibiotics have been used in massive quantities for human and animal medical treatment, and antibiotic resistance genes (ARGs) are of great concern worldwide. Antibiotics and ARGs are exposed to the natural environment through the discharge of medical wastewater, causing great harm to the environment and human health. Biochar has been widely used as a green and efficient adsorbent to remove pollutants. However, pristine and unmodified biochars are not considered sufficient and efficient to cope with the current serious water pollution. Therefore, researchers have chosen to improve the adsorption capacity of biochar through different modification methods. To have a better understanding of the application of modified biochar, this review summarizes the biochar modification methods and their performance, particularly, molecular imprinting and biochar aging are outlined as new modification methods, influencing factors of biochar and modified biochar in adsorption of antibiotics and ARGs and adsorption mechanisms, wherein adsorption mechanism of ARGs on biochar is found to be different than that of antibiotics. After that, the directions of biochar and modified biochar worthy of research and the issues that need attention are proposed. It can be noted that under the current dual carbon policy, biochar may have wider application prospects in future.

The effects of biochar on antibiotic resistance genes (ARGs) removal during different environmental governance processes: A review

Antibiotic resistance genes (ARGs) pollution has been considered as one of the most significant emerging environmental and health challenges in the 21st century, many efforts have been paid to control the proliferation and dissemination of ARGs in the environment. Among them, the biochar performs a positive effect in reducing the abundance of ARGs during different environmental governance processes and has shown great application prospects in controlling the ARGs. Although there are increasing studies on employing biochar to control ARGs, there is still a lack of review paper on this hotspot. In this review, firstly, the applications of biochar to control ARGs in different environmental governance processes were summarized. Secondly, the processes and mechanisms of ARGs removal promoted by biochar were proposed and discussed. Then, the effects of biochar properties on ARGs removal were highlighted. Finally, the future prospects and challenges of using biochar to control ARGs were proposed. It is hoped that this review could provide some new guidance for the further research of this field.

Biochar and Manure Applications Differentially Altered the Class 1 Integrons, Antimicrobial Resistance, and Gene Cassettes Diversity in Paddy Soils

Integrons are genetic components that are critically involved in bacterial evolution and antimicrobial resistance by assisting in the propagation and expression of gene cassettes. In recent decades, biochar has been introduced as a fertilizer to enhance physiochemical properties and crop yield of soil, while manure has been used as a fertilizer for centuries. The current study aimed to investigate the impact of biochar, manure, and a combination of biochar and manure on integrons, their gene cassettes, and relative antimicrobial resistance in paddy soil. Field experiments revealed class 1 (CL1) integrons were prevalent in all samples, with higher concentration and abundance in manure-treated plots than in biochar-treated ones. The gene cassette arrays in the paddy featured a broad pool of cassettes with a total of 35% novel gene cassettes. A majority of gene cassettes encoded resistance to aminoglycosides, heat shock protein, heavy metals, pilus secretory proteins, and twin-arginine translocases (Tat), TatA, TatB, and TatC. Both in combination and solo treatments, the diversity of gene cassettes was increased in the manure-enriched soil, however, biochar reduced the gene cassettes’ diversity and their cassettes array. Manure considerably enhanced CL1 integrons abundance and antimicrobial resistance, whereas biochar amendments significantly reduced integrons and antimicrobial resistance. The results highlighted the differential effects of biochar and manure on integrons and its gene cassette arrays, showing increased abundance of integrons and antibiotic resistance upon manure application and decrease of the same with biochar. The use of biochar alone or in combination with manure could be a beneficial alternative to mitigate the spread of antimicrobial resistance and bacterial evolution in the environment, specifically in paddy soils.

Efficient remediation of antibiotic pollutants from the environment by innovative biochar: current updates and prospects

The increased antibiotic consumption and their improper management led to serious antibiotic pollution and its exposure to the environment develops multidrug resistance in microbes against antibiotics. The entry rate of antibiotics to the environment is much higher than its exclusion; therefore, efficient removal is a high priority to reduce the harmful impact of antibiotics on human health and the environment. Recent developments in cost-effective and efficient biochar preparation are noticeable for their effective removal. Moreover, biochar engineering advancements enhanced biochar remediation performance several folds more than in its pristine forms. Biochar engineering provides several new interactions and bonding abilities with antibiotic pollutants to increase remediation efficiency. Especially heteroatoms-doping significantly increased catalysis of biochar. The main focus of this review is to underline the crucial role of biochar in the abatement of emerging antibiotic pollutants. A detailed analysis of both native and engineered biochar is provided in this article for antibiotic remediation. There has also been discussion of how biochar properties relate to feedstock, production conditions and manufacturing technologies, and engineering techniques. It is possible to produce biochar with different surface functionalities by varying the feedstock or by modifying the pristine biochar with different chemicals and preparing composites. Subsequently, the interaction of biochar with antibiotic pollutants was compared and reviewed. Depending on the surface functionalities of biochar, they offer different types of interactions e.g., π-π stacking, electrostatic, and H-bonding to adsorb on the biochar surface. This review demonstrates how biochar and related composites have optimized for maximum removal performance by regulating key parameters. Furthermore, future research directions and opportunities for biochar research are discussed.

Liming mitigates the spread of antibiotic resistance genes in an acid black soil

The threat of antibiotic resistance genes (ARGs) caused by animal manure application to human health has been the focus of attention in agriculture. Applying lime to acid soil for the amelioration of soil acidity is a prevailing agricultural practice. However, the role of lime on the spread of antibiotic resistome from soil to plant is unknown. In this study, a pot experiment of lettuce was established in the acid black soil with lime addition at the rate (w/w) of 0%, 0.08%, 0.16%, and 0.32% of the total soil mass to explore the transmission of ARGs introduced by the fresh poultry manure in the soil-plant system. The bulk and rhizosphere soils as well as the leaf samples were collected after lettuce was cultivated for 60 days, the bacterial community and antibiotic resistome in these samples were determined by using Illumina sequencing and high-throughput quantitative PCR (HT-qPCR) methods, respectively. Results showed that lime application decreased the number and abundance of ARGs and slowed down the spread of manure-derived ARGs in the soil-plant system. The ARGs and bacterial community composition were significantly varied among bulk soils, rhizosphere soils and leaf endophyte, and also influenced by lime within the same sampling types. The structural equation model further demonstrated that the lime addition had a negative effect on ARG diversity, which was also indirectly regulated by bacterial community diversity. These findings suggest that lime addition can alleviate the level and dissemination of ARGs in soils and provide a potential measure to control the spread of ARGs derived from animal manure.

Effect of biochar addition on the dynamics of antibiotic resistant bacteria during the pig manure composting

In present study, the taxonomic variation of antibiotic resistant bacteria (ARB) in pig manure (PM) composting with coconut shell biochar (CSB) and bamboo biochar (BB) addition was investigated. The experiment was divided into three treatments: T1 (as control or without biochar amendment), T2 was added 10% coconut shell biochar and T3 supplemented with 10% bamboo biochar. The initial feed stock were properly homogenized using a mechanical crusher. PM and wheat straw (WS) were mixed in a 5: 1 dry weight ratio to adjust the initial carbon/nitrogen ratio 25:1, bulk density to ~0.5 (kg/L) and ~60% moisture content, respectively. This experiment was lasted for 42 days. The results indicated the bacterial communities in the three treatments were more different in terms of relative abundance and diversity of dominant bacteria. The control group had the highest abundance of Kingdome bacteria. The changes in ARB was noticed by variation in the relative abundances of Actinobacteria, Proteobacteria, Firmicutes and Bacteroidota. At the end of composting (on day 42), the total RAs of ARB at the class, order, and family levels were considerably reduced in T2 and T3 by ~35.78-38.75%, 36.42-40.63% and 45.82-47.70%, respectively. But in T1 was decreased by 6.16-8.62%, 7.93-8.72% and 8.70-10.15%, as compared with the day 0 sample. However, the CSB was much more effective to reduce 55 to 60% of ARB than T3 or BB applied treatment has 40 to 42% ARB reduction, while control has certainly very less RAa of ARB reduction. Finally, the biochar amendment was significant approach to mitigate the total ARB abundance in compost and it's further used for organic farming purposes.

Individual and combined applications of biochar and pyroligneous acid mitigate dissemination of antibiotic resistance genes in agricultural soil

Remediation of agricultural soils polluted with antibiotic resistance genes (ARGs) is important for protecting food safety and human health. However, the feasibility of co-application of biochar and pyroligneous acid, two multifunctional soil amendments, for mitigating dissemination of soil ARGs is unknown. Thus, a woody biochar (BC450) and its by-product, pyroligneous acid (PA450) simultaneously produced at 450 °C from blended wood wastes, were used to compare their individual and combined effects on soil ARG abundance using a 65-day pot experiment planted with leafy vegetable Brassica chinensis L. The individual and combined applications of PA450 and BC450 significantly reduced the absolute abundance of ARGs by 65.7-81.4% and 47.5-72.9% in the corresponding rhizosphere and bulk soil. However, the co-application showed little synergistic effect, probably due to the counteractive effect of BC450 on the PA450-mitigated soil ARG proliferation, resulted from the promoted soil bacterial growth and/or adsorption of antimicrobial components of PA450 by BC450. The decreased abundances of mobile genetic element intI1 and Tn916/1545 in the PA450 treatments demonstrated the potential of PA450 for weakening horizontal gene transfer (HGT). Furthermore, weakened HGT by individual PA450, lowered availability of heavy metals by individual BC450, and different bacterial community (e.g., reduced ARGs bacterial host) together with improved soil properties from co-application of PA450 and BC450 all contributed to the reduced ARG level. This study highlighted the feasibility of co-applications of biochar and pyroligneous acid amendment for mitigating soil ARG pollution. These findings provide important information for developing eco-friendly technologies using biochar and pyroligneous acid in remediating ARG-contaminated soils.

Interaction of pig manure-derived dissolved organic matter with soil affects sorption of sulfadiazine, caffeine and atenolol pharmaceuticals

Pharmaceutically active compounds (PhACs) released into the environment have an adverse impact on the soil and water ecosystem as well as human health. Sorption of PhACs by soils and its potential modification through introduced DOM in the applied animal manure or treated wastewater (TWW) determines the mobility and environmental relevance of PhACs. Sulfadiazine, caffeine and atenolol were selected as target PhACs to investigate their sorption behaviors by five selected arable soils in the absence and presence of pig manure DOM. Sulfadiazine was least sorbed, followed by caffeine and atenolol according to the Freundlich sorption isotherm fit (soil average K_f [μg^(1-n) mLⁿ g^-1] 4.07, 9.06, 18.92, respectively). The addition of manure DOM (31.34 mg C L^-1) decreased the sorption of sulfadiazine and especially of caffeine and atenolol (average K_f 3.04, 6.17, 5.79, respectively). Freundlich sorption isotherms of the PhACs became more nonlinear in the presence of manure DOM (Freundlich exponent n changed from 0.74-1.40 to 0.62-1.12), implying more heterogeneous sorption of PhACs in soil-DOM binary systems. Sorption competition of DOM molecules with sulfadiazine and caffeine mostly contributed to their decreased soil sorption when DOM was present. In contrast, the formation of DOM-atenolol associates in the solution phase caused the largely decreased soil sorption of atenolol in the presence of DOM. It is suggested that DOM concentration (e.g., ≥ 60 mg C L^-1) and its interaction with PhACs should be taken into consideration when assessing the environmental impact of land application of animal manure or irrigation with TWW.

Upgrading residues from wastewater and drinking water treatment plants as low-cost adsorbents to remove extracellular DNA and microorganisms carrying antibiotic resistance genes from treated effluents

Wastewater treatment is challenged by the continuous emergence of chemical and biological contaminants. Disinfection, advanced oxidation, and activated carbon technologies are accessible in high-income countries to suppress them. Low-cost, easily implementable, and scalable solutions are needed for sanitation across regions. We studied the properties of low-cost absorbents recycled from drinking water and wastewater treatment plant residues to remove environmental DNA and xenogenetic elements from used water. Materials characteristics and DNA adsorption properties of used iron-oxide-coated sands and of sewage-sludge biochar obtained by pyrolysis of surplus activated sludge were examined in bench-scale batch and up-flow column systems. Adsorption profiles followed Freundlich isotherms, suggesting a multilayer adsorption of nucleic acids on these materials. Sewage-sludge biochar exhibited high DNA adsorption capacity (1 mg g^-1) and long saturation breakthrough times compared to iron-oxide-coated sand (0.2 mg g^-1). Selected antibiotic resistance genes and mobile genetic elements present on the free-floating extracellular DNA fraction and on the total environmental DNA (i.e., both extra/intracellular) were removed at 85% and 97% by sewage-sludge biochar and at 54% and 66% by iron-oxide-coated sand, respectively. Sewage-sludge biochar is attractive as low-cost adsorbent to minimize the spread of antimicrobial resistances to the aquatic environment while strengthening the role of sewage treatment plants as resource recovery factories.

Role played by the environment in the emergence and spread of antimicrobial resistance (AMR) through the food chain

The role of food-producing environments in the emergence and spread of antimicrobial resistance (AMR) in EU plant-based food production, terrestrial animals (poultry, cattle and pigs) and aquaculture was assessed. Among the various sources and transmission routes identified, fertilisers of faecal origin, irrigation and surface water for plant-based food and water for aquaculture were considered of major importance. For terrestrial animal production, potential sources consist of feed, humans, water, air/dust, soil, wildlife, rodents, arthropods and equipment. Among those, evidence was found for introduction with feed and humans, for the other sources, the importance could not be assessed. Several ARB of highest priority for public health, such as carbapenem or extended-spectrum cephalosporin and/or fluoroquinolone-resistant Enterobacterales (including Salmonella enterica), fluoroquinolone-resistant Campylobacter spp., methicillin-resistant Staphylococcus aureus and glycopeptide-resistant Enterococcus faecium and E. faecalis were identified. Among highest priority ARGs bla CTX -M, bla VIM, bla NDM, bla OXA -48-like, bla OXA -23, mcr, armA, vanA, cfr and optrA were reported. These highest priority bacteria and genes were identified in different sources, at primary and post-harvest level, particularly faeces/manure, soil and water. For all sectors, reducing the occurrence of faecal microbial contamination of fertilisers, water, feed and the production environment and minimising persistence/recycling of ARB within animal production facilities is a priority. Proper implementation of good hygiene practices, biosecurity and food safety management systems is very important. Potential AMR-specific interventions are in the early stages of development. Many data gaps relating to sources and relevance of transmission routes, diversity of ARB and ARGs, effectiveness of mitigation measures were identified. Representative epidemiological and attribution studies on AMR and its effective control in food production environments at EU level, linked to One Health and environmental initiatives, are urgently required.

Removal of abamectin and conventional pollutants in vertical flow constructed wetlands with Fe-modified biochar

To improve the ability of constructed wetlands to remove abamectin (ABM) and nutrients, the influence of four different substrates on constructed wetlands was studied. Four vertical up-flow constructed wetlands (UVCWs) were established to treat simulated agricultural wastewater: CW1 (quartz sand + pebbles), CW2 (pebbles + coke), CW3 (Fe-modified biochar + pebbles + coke), and CW4 (unmodified biochar + pebbles + coke). Under different combinations of hydraulic loading and organic loading, CW3 was extremely effective at removing nitrogen compared with CW1, CW2 and CW4. We found that CW3 was the most effective at treating ABM and conventional pollutants. The highest efficiency of removal of abamectin (99%), COD (98%), NH₄ ⁺-N (65%), and TP (80%) was obtained in CW3. These results were directly verified by microbiological tests and microbial community analysis. The microbial diversity of CW3 and CW4 was significantly higher than those of CW1 and CW2. Fe-modified biochar provides a feasible and effective amendment for constructed wetlands to improve the nitrogen removal for C/N (2.5 : 1-5 : 1) wastewater by the ability of microbes to remove nitrogen. Fe-modified bamboo charcoal can be used in engineering as a new type of green environmental protection constructed wetland filler in the future.