Removal Of Antibiotic Resistance Genes Research Articles

Impact of earthworms on antibiotic resistance genes removal in ampicillin-contaminated soil through bacterial community alteration.

The emergence of antibiotic resistance genes (ARGs) as contaminants in soil poses a significant threat to public health. Earthworms (Eisenia foetida), which are common inhabitants of soil, have been extensively studied for their influence on ARGs. However, the specific impact of earthworms on penicillin-related ARGs remains unclear. In this study, we investigate the role of earthworms in mitigating ARGs, specifically penicillin-related ARGs, in ampicillin-contaminated soil. Utilizing high-throughput quantitative PCR (HT-qPCR), we quantified a significant reduction in the relative abundance of penicillin-related ARGs in soil treated with earthworms, showing a decrease with a p-value of <0.01. Furthermore, high-throughput 16S rRNA gene sequencing revealed that earthworm intervention markedly alters the microbial community structure, notably enhancing the prevalence of specific bacterial phyla such as Proteobacteria, Firmicutes, Chloroflexi, and Tenericutes. Our findings not only demonstrate the effectiveness of earthworms in reducing the environmental load of penicillin-related ARGs but also provide insight into the alteration of microbial communities as a potential mechanism. This research contributes to our understanding of the role of earthworms in mitigating the spread of antibiotic resistance and provides valuable insights for the development of strategies to combat this global health issue.

Removal of intracellular antibiotic resistance genes by activating peroxymonosulfate with Co3O4@CNT catalytic membrane

The removal of antibiotic resistance genes (ARGs) is crucial to prevent the proliferation of antibiotic resistance. In this study, we successfully removed intracellular ARGs using the PMS/Co@CM system, which involved activating peroxymonosulfate (PMS) with a catalytic membrane composed of Co3O4 and carbon nanotubes. In the PMS/Co@CM system, 1O2 was the primary reactive oxygen species (ROS) responsible for intracellular ARGs removal. However, the presence of sulfamethoxazole (SMX) in the water samples significantly reduced the efficiency of removing intracellular ARGs in the PMS/Co@CM system although SMX was degraded by •SO4−. This can be attributed to the selective pressure of SMX, which elevated intracellular Superoxide Dismutase (SOD) levels while decreasing Propidium Iodide (PI) levels in cells. Consequently, this led to heightened antioxidant defense and reduced membrane permeability, thereby enhancing cell resistance to 1O2 generated by the PMS/Co@CM system. Encouragingly, a typical UV disinfection process facilitated the removal of residual intracellular ARGs in the effluent of the PMS/Co@CM system, attributed to decreased SOD levels and increased intracellular 1O2 by UV irradiation. These findings contribute to the theoretical understanding of effective ARGs removal and aid in the development of more efficient removal technologies.

Ceftiofur in swine manure contributes to reducing pathogens and antibiotic resistance genes during composting

Aerobic composting is a common way for the disposal of feces produced in animal husbandry, and can reduce the release of antibiotic resistance genes (ARGs) from feces into the environment. In this study, we collected samples from two distinct treatments of swine manure compost with and without ceftiofur (CEF), and identified the ARGs, mobile genetic elements (MGEs), and bacterial community by metagenomic sequencing. The impacts of CEF on the bacterial community composition and fate of ARGs and MGEs were investigated. With increasing composting temperature and pH, the concentration of CEF in the manure decreased rapidly, with a degradation half-life of 1.12 d and a 100% removal rate after 10 d of aerobic composting. Metagenomics demonstrated that CEF in the manure might inhibit the growth of Firmicutes and Proteobacteria, thereby reducing some ARGs and MGEs hosted by these two bacteria, which was further confirmed by the variations of ARGs and MGEs. A further redundancy analysis suggested that pH and temperature are key environmental factors affecting ARG removal during composting, and intI1 and bacterial communities also have significant influence on ARG abundance. These results are of great significance for promoting the removal of some ARGs from animal manure by controlling some key environmental factors and the type of antibiotics used in animals.

Pyrite from acid mine drainage promotes the removal of antibiotic resistance genes and mobile genetic elements in karst watershed with abundant calcium carbonate

More information is needed to fully comprehend how acid mine drainage (AMD) affects the phototransformation of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) in karst water and sewage-irrigated farmland soil with abundant carbonate rocks (CaCO3) due to increasing pollution of AMD formed from pyrite (FeS2). The results showed FeS2 accelerated the inactivation of ARB with an inactivation of 8.7 log. Notably, extracellular and intracellular ARGs and mobile genetic elements (MGEs) also experienced rapid degradation. Additionally, the pH of the solution buffered by CaCO3 significantly influenced the photo-inactivation of ARB. The Fe2+ in neutral solution was present in Fe(II) coordination with strong reducing potential and played a crucial role in generating •OH (7.0 μM), which caused severe damage to ARB, ARGs, and MGEs. The •OH induced by photo-Fenton of FeS2 posed pressure to ARB, promoting oxidative stress response and increasing generation of reactive oxygen species (ROS), ultimately damaging cell membranes, proteins and DNA. Moreover, FeS2 contributed to a decrease in MIC of ARB from 24 mg/L to 4 mg/L. These findings highlight the importance of AMD in influencing karst water and sewage-irrigated farmland soil ecosystems. They are also critical in advancing the utilization of FeS2 to inactivate pathogenic bacteria.

Mechanisms for more efficient antibiotics and antibiotic resistance genes removal during industrialized treatment of over 200 tons of tylosin and spectinomycin mycelial dregs by integrated meta-omics

To mitigate the environmental risks posed by the accumulation of antibiotic mycelial dregs (AMDs), this study first attempted over 200 tons of mass production fermentation (MP) using tylosin and spectinomycin mycelial dregs alongside pilot-scale fermentation (PS) for comparison, utilizing the integrated-omics and qPCR approaches. Co-fermentation results showed that both antibiotics were effectively removed in all treatments, with an average removal rate of 92%. Antibiotic resistance gene (ARG)-related metabolic pathways showed that rapid degradation of antibiotics was associated with enzymes that inactivate macrolides and aminoglycosides (e.g., K06979, K07027, K05593). Interestingly, MP fermentations with optimized conditions had more efficient ARGs removal because homogenization permitted faster microbial succession, with more stable removal of antibiotic resistant bacteria and mobile genetic elements. Moreover, Bacillus reached 75% and secreted antioxidant enzymes that might inhibit horizontal gene transfer of ARGs. The findings confirmed the advantages of MP fermentation and provided a scientific basis for other AMDs.

Mechanisms on the removal of gram-negative/positive antibiotic resistant bacteria and inhibition of horizontal gene transfer by ferrate coupled with peroxydisulfate or peroxymonosulfate

The existence of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) has been a global public environment and health issue. Due to the different cell structures, gram-positive/negative ARB exhibit various inactivation mechanisms in water disinfection. In this study, a gram-negative ARB Escherichia coli DH5α (E. coli DH5α) was used as a horizontal gene transfer (HGT) donor, while a gram-positive ARB Bacillus as a recipient. To develop an efficient and engineering applicable method in water disinfection, ARB and ARGs removal efficiency of Fe(VI) coupled peroxydisulfate (PDS) or peroxymonosulfate (PMS) was compared, wherein hydroxylamine (HA) was added as a reducing agent. The results indicated that Fe(VI)/PMS/HA showed higher disinfection efficiency than Fe(VI)/PDS/HA. When the concentration of each Fe(VI), PMS, HA was 0.48 mM, 5.15 log E. coli DH5α and 3.57 log Bacillus lost cultivability, while the proportion of recovered cells was 0.0017 % and 0.0566 %, respectively, and HGT was blocked. Intracellular tetA was reduced by 2.49 log. Fe(IV) and/or Fe(V) were proved to be the decisive reactive species. Due to the superiority of low cost as well as high efficiency and practicality, Fe(VI)/PMS/HA has significant application potential in ARB, ARGs removal and HGT inhibition, offering a new insight for wastewater treatment.

Efficient removal of size-fractionated antibiotic resistance genes (ARGs) in WWTPs secondary effluent by vacuum ultraviolet (VUV) activated potassium peroxymonosulfate (PMS)

Antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) in secondary effluent from wastewater treatment plants (WWTPs) have a size-fractionated character and conventional processes have difficulties in removing ARGs and MGEs. Therefore, this study aimed to explore the removal efficiency, removal mechanism and regeneration potential of size-fractionated ARGs and MGEs by vacuum ultraviolet (VUV)-activated peroxymonosulfate (PMS) and ascertain their potential hosts in secondary effluent. The proportion of particle-associated (PA)-ARGs and PA-MGEs was 85.07 %, followed by free-living (FL) fraction (14.91 %) and cell-free (CF) fraction (0.02 %). More than 95.00 %∼99.99 % of ARGs and MGEs in PA- and CF- fractions were removed by VUV/PMS, but the average removal efficiency of FL-ARGs and FL-MGEs was 66.15 %. Compared to the regeneration potential of PA- and CF-ARGs and MGEs (0.02 < C/C0 < 5.27), the regeneration occurred mainly in FL-ARGs and FL-MGEs (0.08 < C/C0 < 24.06). ·OH was the dominant radical (16.810 × 10-6 mol/L) in VUV/PMS for the removal of size-fractionated ARGs and MGEs from the secondary effluent, while SO4-· (4.478 × 10-6 mol/L) played a supporting role in the system based on the quenching experiment, electron paramagnetic resonance spectrometer and probe experiments. Based on full-scale classification, conditionally rare or abundant taxa (CRAT) were the core potential hosts in PA-, FL- and CF- fractions, while rare taxa (RT) and conditionally rare taxa (CRT) potential hosts were more diverse in the three fractions. This study suggests that VUV/PMS can effectively remove size-fractionated ARGs and MGEs from secondary effluent and thereby obviously reduce their dissemination risk to receiving water bodies, providing technical support for the engineering application of VUV/PMS in full-scale WWTPs.

The synergistic effect of periodate/ferrate (VI) system on disinfection of antibiotic resistant bacteria and removal of antibiotic resistant genes: The dominance of Fe (IV)/Fe (V)

The proliferation of antibiotic resistant genes (ARGs) and antibiotic resistant bacteria (ARB) caused by antibiotic abuse has raised concerns about the global infectious-disease crisis. This study employed periodate (PI)/ferrate (VI) (Fe (VI)) system to disinfect Gram-negative ARB (Escherichia coli DH5α) and Gram-positive bacteria (Bacillus subtilis ATCC6633). The PI/Fe (VI) system could inactivate 1 × 108 CFU/mL of Gram-negative ARB and Gram-positive bacteria by 4.0 and 2.8 log in 30 min. Neutral and acidic pH, increase of PI dosage and Fe (VI) dosage had positive impacts on the inactivation efficiency of ARB, while alkaline solution and the coexistence of 10 mM Cl-, NO3-, SO42- and 20 mg/L humic acid had slightly negative impacts. The reactive species generated by PI/Fe (VI) system could disrupt the integrity of cell membrane and wall, leading to oxidative stress and lipid peroxidation. Intracellular hereditary substance, including DNA and ARGs (tetA), would leak into the external environment through damaged cells and be degraded. The electron spin resonance analysis and quenching experiments indicated that Fe (IV)/Fe (V) played a leading role in disinfection. Meanwhile, PI/Fe (VI) system also had an efficient removal effect on sulfadiazine, which was expected to inhibit the ARGs transmission from the source.

Synergistic removal of total petroleum hydrocarbons and antibiotic resistance genes in Yellow River Delta wetlands contaminated soil composting regulated by biogas slurry addition

The interactive effects between the emerging contaminant antibiotic resistance genes (ARGs) and the traditional pollutant total petroleum hydrocarbons (TPHs) in contaminated soils remain unclear. The synergistic removal of TPHs and ARGs from composted contaminated soil, along with the microbial mechanisms driven by the addition of biogas slurry, have not yet been investigated. This study explored the impact of biogas slurry on the synergistic degradation mechanisms and bacterial community dynamics of ARGs and TPHs in compost derived from contaminated soil. The addition of biogas slurry resulted in a reduction of targeted ARGs and mobile genetic elements (MGEs) by 9.96%–95.70% and 13.32%–97.66%, respectively. Biogas slurry changed the succession of bacterial communities during composting, thereby reducing the transmission risk of ARGs. Pseudomonas, Cellvibrio, and Devosia were identified as core microorganisms in the synergistic degradation of ARGs and TPHs. According to the partial least squares path model, temperature and NO3− indirectly influenced the removal of ARGs and TPHs by directly regulating the abundance and composition of host microbes and MGEs. In summary, the results of this study contribute to the high-value utilization of biogas slurry and provide methodological support for the low-cost remediation of contaminated soils.

Potential of combined reactor and static composting applications for the removal of heavy metals and antibiotic resistance genes from chicken manure

Chicken manure (CM) can pose a serious threat to environmental and human health, and need to be managed properly. The compost can effectively treat CM. However, there is limited research on the heavy metals and antibiotic resistance genes (ARGs) during compost CM. In this study, the combined application of reactor and static composting (RSC) was used to produce organic fertilizer of CM (OCM), and heavy metals, ARGs and bacterial community structure was investigated. The results show that RSC could be used to produce OCM, and OCM meet the National organic fertilizer standard (NY/T525-2021). Compared to the initial CM, DTPA-Cu, DTPA-Zn, DTPA-Pb, DTPA-Cr, DTPA-Ni and DTPA-As in OCM decreased by 40.83%, 23.73%, 34.27%, 38.62%, 16.26%, and 43.35%, respectively. RSC decreased the relative abundance of ARGs in CM by 84.06%, while the relative abundance of sul1 and ermC increased. In addition, the relative abundance and diversity of ARGs were mainly influenced by the bacterial community, with Actinobacteria, Firmicutes, and Proteobacteria becoming the dominant phyla during composting, and probably being the main carriers and dispersers of most of the ARGs. Network analyses confirmed that Gracilibacillus, Lactobacillus, Nocardiopsis, Mesorhizobium and Salinicoccus were the main potential hosts of ARGs, with the main potential hosts of sul1 and ermC being Mesorhizobium and Salinicoccus. The passivation and physicochemical properties of heavy metals contribute to the removal of ARGs, with sul1 and ermC being affected by the toal heavy metals. Application of RSC allows CM to produce mature, safe organic fertilizer after 32 d and reduces the risk of rebound from ARGs, but the issues of sul1 and ermC gene removal cannot be ignored.

Deciphering the removal of antibiotics and the antibiotic resistome from typical hospital wastewater treatment systems

Hospital wastewater treatment systems (HWTSs) are a significant source and reservoir of antibiotic resistance genes (ARGs) and a crucial hub for transmitting ARGs from clinical to natural environments. However, there is a lack of research on the antibiotic resistome of clinical wastewater in HWTSs. In this study, we used metagenomics to analyze the prevalence and abundance of ARGs in five typical HWTSs. A total of 17 antibiotics from six categories were detected in the five HWTSs; β-lactam antibiotics were found at the highest concentrations, with up to 4074.08 ng·L−1. We further found a total of 21 ARG types and 1106 subtypes of ARGs with the highest percentage of multi-drug resistance genes (evgS, msbA, arlS, and baeS). The most abundant last-resort ARGs were mcr, which were detected in 100 % of the samples. HWTSs effluent is a major pathway for the transmission of last-resort ARGs into urban wastewater networks. The removal of antibiotics, antibiotic-resistant bacteria, and ARGs from HWTSs was mainly achieved by tertiary treatment, i.e., chlorine disinfection, but antibiotics and ARGs were still present in the HWTSs effluent or even increased after treatment. Moreover, antibiotics and heavy metals (especially mercury) in hospital effluents can exert selective pressure for antibiotic resistance, even at low concentrations. Qualitative analyses based on metagenome-assembled genome analysis revealed that the putative hosts of the identified ARGs are widely distributed among Pseudomonas, Acidovorax, Flavobacterium, Polaromonas, and Arcobacter. Moreover, we further assessed the clinical availability of ARGs and found that multidrug ARGs had the highest clinical relevance values. This study provides new impulses for monitoring and removing antibiotics and ARGs in the hospital sewage treatment process.

Temperature-phased anaerobic sludge digestion effectively removes antibiotic resistance genes in a full-scale wastewater treatment plant

Sludge is a major by-product and the final reservoir of antibiotic resistance genes (ARGs) in wastewater treatment plants (WWTPs). Temperature-phased anaerobic digestion (TPAD), consisting of thermophilic anaerobic digestion (AD) (55 °C) and mesophilic AD processes (37 °C), has been implemented in WWTPs for sludge reduction while improving the biomethane production. However, the impact of TPAD on the ARGs' fate is still undiscovered in lab-scale experiments and full-scale WWTPs. This study, for the first time, investigated the fate of ARGs during the TPAD process across three seasons in a full-size WWTP. Ten typical ARGs and one integrase gene of class 1 integron (intI1) involving ARGs horizontal gene transfer were examined in sludge before and after each step of the TPAD process. TPAD reduced aac(6′)-Ib-cr, blaTEM, drfA1, sul1, sul2, ermb, mefA, tetA, tetB and tetX by 87.3–100.0 %. TPAD reduced the overall average absolute abundance of targeted ARGs and intI1 by 92.39 % and 92.50 %, respectively. The abundance of targeted ARGs in sludge was higher in winter than in summer and autumn before and after TPAD. During the TPAD processes, thermophilic AD played a major role in the removal of ARGs, contributing to >60 % removal of ARGs, while the subsequent mesophilic AD contributed to a further 31 % removal of ARGs. The microbial community analysis revealed that thermophilic AD reduced the absolute abundance of ARGs hosts, antibiotic resistant bacteria. In addition, thermophilic AD reduced the abundance of the intI1, while the intI1 did not reproduce during the mesophilic AD, also contributing to a decline in the absolute abundance of ARGs in TPAD. This study demonstrates that TPAD can effectively reduce the abundance of ARGs in sludge, which will suppress the transmission of ARGs from sludge into the natural environment and deliver environmental and health benefits to our society.

Leveraging machine learning for prediction of antibiotic resistance genes post thermal hydrolysis-anaerobic digestion in dairy waste

Anaerobic digestion holds promise as a method for removing antibiotic resistance genes (ARGs) from dairy waste. However, accurately predicting the efficiency of ARG removal remains a challenge. This study introduces a novel appproach utilizing machine learning to forecast changes in ARG abundances following thermal hydrolysis-anaerobic digestion (TH-AD) treatment. Through network analysis and redundancy analyses, key determinants of affect ARG fluctuations were identified, facilitating the development of machine learning models capable of accurately predicting ARG changes during TH-AD processes. The decision tree model demonstrated impressive predictive power, achieving an impessive R2 value of 87% against validation data. Feature analysis revealed that the genes intI2 and intI1 had a critical impact on the absolute abundance of ARGs. The predictive model developed in this study offers valuable insights for improving operational and managerial practices in dairy waste treatment facilities, with the ultimate goal of mitigating the spread of antibiotic resistance.

The fate of antibiotic resistance genes in wastewater containing microalgae treated by chlorination, ultra-violet, and Fenton reaction

Antibiotic resistance genes (ARGs) and bacteria (ARBs) in the effluent of wastewater treatment plants (WWTPs) are of utmost importance for the dissemination of ARGs in natural aquatic environments. Therefore, there is an urgent need for effective technologies to eliminate WWTP ARGs/ARBs and mitigate the associated risks posed by the discharged ARG in aquatic environments. To test the effective technology for eliminating ARGs/ARBs, we compared the removal of ARGs and ARBs by three different tertiary treatments, namely ultra-violet (UV) disinfection, chlorination disinfection, and Fenton oxidation. Then, the treated wastewater was co-cultured with Chlorella vulgaris (representative of aquatic biota) to investigate the fate of discharged ARGs into the aquatic environment. The results demonstrated that chlorination (at a chlorine concentration of 15 mg/L) and Fenton (at pH 2.73, with 0.005 mol/L Fe2+ and 0.0025 mol/L H2O2) treatment showed higher efficacy in ARG removal (1.8 - 4.17 logs) than UV treatment (15 min) (1.29 - 3.87 logs). Moreover, chlorine at 15 mg/L and Fenton treatment effectively suppressed ARB regeneration while UV treatment for 15 min could not. Regardless of treatments tested in this study, the input of treated wastewater to the Chlorella system increased the number of ARGs and mobile genetic elements (MGEs), indicating the potential risk of ARG dissemination associated with WWTP discharge. Among the wastewater-Chlorella co-culture systems, chlorination resulted in less of an increase in the number of ARGs and MGEs compared to Fenton and UV treatment. When comparing the wastewater systems to the co-culture systems, it was observed that Chlorella vulgaris reduced the number of ARGs and MGEs in chlorination and UV-treated wastewater; however, Chlorella vulgaris promoted ARG survival in Fenton-treated water, suggesting that aquatic microalgae might act as a barrier to ARG dissemination. Overall, chlorination treatment not only effectively removes ARGs and inhibits ARB regeneration but also shows a lower risk of ARG dissemination. Therefore, chlorination is recommended for practical application in controlling the spread of discharged ARGs from WWTP effluent in natural aquatic environments.

Different mobile counter ion types of magnetic ion-exchange resin coupling with ozonation treatment of the organic matter, antibiotic resistance genes, and pathogens in secondary effluent

Advanced treatment and reuse of secondary effluents (SE) from wastewater treatment plants is considered an effective method of alleviating the conflict between water supply and demand. However, the effective removal of organic matter, antibiotic resistance genes (ARGs), and pathogens in SE is key to ensure the safety of reclaimed water. In this study, the effectiveness of three types of magnetic ion-exchange resins (R-X, where X refers to –OH, –HCO3, and -Cl) coupled with ozonation (R + O) in reducing different types of carbon, pathogens, intracellular and extracellular antibiotic resistance genes (iARGs and eARGs), and microbial communities in SE was investigated. The results indicated that R-Cl was the best pre-treatment resin for ozonation. R-Cl + O (8 mL/L R-Cl adsorption for 30 min, followed by 15 min of 8 mg/L ozonation) achieved removal efficiencies of 49.7 %, 86.6 %, 99.9 %, 87.1 %, and 99.9 % for dissolved organic carbon, UV254, ΣiARGs, ΣeARGs, and Σpathogens, respectively. Ozonation was more effective than resin adsorption in the removal of ARGs, and R-Cl + O had the lowest rebounding potential for iARGs and pathogens. In addition, R-OH had the lowest removal efficiency of organic matter, iARGs, and pathogens compared to other types of resins owing to the electrostatic repulsion mechanism. Molecular dynamics simulations and average reduced density gradient analysis revealed that the quaternary amine sites of the resin had a positive surface electrostatic potential, which could firmly adsorb double-stranded deoxyribonucleic acid by electrostatic action. Ozonation effectively reduced the risk of ARGs and pathogens in the effluent of resin. The R + O treatment reduced organic matter, ARGs, and pathogens more effectively than single treatment, despite the different anionic groups of the resin.

Simultaneous removal of antibiotic resistance genes and improved dewatering ability of waste activated sludge by Fe(II)-activated persulfate oxidation

Waste activated sludge properties vary widely with different regions due to the difference in living standards and geographical distribution, making a big challenge to developing a universally effective sludge dewatering technique. The Fe(II)-activated persulfate (S2O82−) oxidation process shows excellent ability to disrupt sludge cells and extracellular polymeric substances (EPS), and release bound water from sludge flocs. In this study, the discrepancies in the physicochemical characteristics of sludge samples from seven representative cities in China (e.g., dewaterability, EPS composition, surface charge, microbial community, relative abundance of antibiotic resistance genes (ARGs), etc.) were investigated, and the role of Fe(II)-S2O82− oxidation in enhancing removal of antibiotic resistance genes and dewatering ability were explored. The results showed significant differences between the EPS distribution and chemical composition of sludge samples due to different treatment processes, effluent sources, and regions. The Fe(II)-S2O82− oxidation pretreatment had a good enhancement of sludge dewatering capacity (up to 76 %). Microbial analysis showed that the microbial community in each sludge varied significantly depending on the types of wastewater, the wastewater treatment processes, and the regions, but Fe(II)-S2O82− oxidation was able to attack and rupture the sludge zoogloea indiscriminately. Genetic analysis further showed that a considerable number of ARGs were detected in all of these sludge samples and that Fe(II)-S2O82− oxidation was effective in removing ARGs by higher than 90 %. The highly active radicals (e.g., SO4−·, ·OH) produced in this process caused drastic damage to sludge microbial cells and DNA stability while liberating the EPS/cell-bound water. Co-occurrence network analysis highlighted a positive correlation between population distribution and ARGs abundance, while variations in microbial communities were linked to regional differences in living standards and level of economic development. Despite these variations, the Fe(II)-S2O82− oxidation consistently achieved excellent performance in both ARGs removal and sludge dewatering. The significant modularity of associations between different microbial communities also confirms its ability to reduce horizontal gene transfer (HGT) by scavenging microbes.

Partially saturated vertical surface flow constructed wetland for emerging contaminants and antibiotic resistance genes removal from wastewater: The effect of bioaugmentation with Trichoderma

The scientific significance of this work involved in investigating the removal of contaminants of emerging concern (CECs) and antibiotic resistance genes (ARGs) at pilot-scale with partially saturated vertical flow constructed wetland either bioaugmented or not with the Trichoderma asperellum (strain T34) by means of the non-target liquid chromatography high-resolution mass spectrometry and SmartChip™ Real-Time PCR methodological approaches. Bioaugmentation testing was successful as Trichoderma was able to grow in competitive conditions resulting from the use of secondary treated domestic wastewater. There was a clear relationship between the removal efficiency (RE) and the biodegradability as well as the sorption capacity of the identified compounds. The most easily eliminated compounds were those which are known to be readily biodegradable (e.g., nicotine). Interestingly, from 22 compounds with RE > 65 %, 17 compounds have a log Dow between 0 and 3 (optimal plant uptake). The most significant beneficial effect was observed with benzotriazole and diclofenac. The most difficult compounds to be eliminated were the most polar ones (log Dow < 0) such as melamine. High variability in removal efficiency over the course of a four-week experiment remained the chief constraint for the proper assessment of treatment performances. Transformation products (TPs) were also investigated. N-oxide TPs and 14-hydroxyclarithromycin were formed in wetland treatment while TPs which were prone to undergo further N-dealkylation or hydroxylation reactions were partly eliminated. Bioaugmented wetland treatments caused a shift in the composition of ARGs but there was no statistical difference in average rates of ARGs removal.

Metagenomic absolute quantification of antibiotic resistance genes and virulence factor genes-carrying bacterial genomes in anaerobic digesters

Sewage treatment works have been considered as hotspots for the dissemination of antibiotic resistance genes (ARGs). Anaerobic digestion (AD) has emerged as a promising approach for controlling the spread of ARGs while destroying biomass in sludge. Evaluating the impact of AD on ARG removal relies on the absolute quantification of ARGs. In this study, we quantified the ARG concentrations in both full-scale and lab-scale AD systems using a cellular spike-ins based absolute quantification approach. Results demonstrated that AD effectively removed 68 ± 18 %, 55 ± 12 %, and 57 ± 19 % of total ARGs in semi-continuous AD digesters, with solid retention times of 15, 20, and 25 days, respectively. The removal efficiency of total ARGs increased as the AD process progressed in the batch digesters over 40 days. A significant negative correlation was observed between digestion time and the concentrations of certain ARG types, such as beta-lactam, sulfonamide, and tetracycline. However, certain potential pathogenic antibiotic resistant bacteria (PARB) and multi-resistant high-risk ARGs-carrying populations robustly persisted throughout the AD process, regardless of the operating conditions. This study highlighted the influence of the AD process and its operating parameters on ARG removal, and revealed the broad spectrum and persistence of PARB in AD systems. These findings provided critical insights for the management of microbial hazards.

Antibiotics and antibiotic resistance genes removal in biological aerated filter

Two laboratory-level biological aerated filters (BAF) were constructed to explore their treatment capacity for simulated antibiotic wastewater at high (1 - 16 mg/L) and low (0 - 0.5 mg/L) concentrations. Results showed that BAF was capable of removing both sulfonamides and tetracyclines with an efficiency of over 90 % at 16 mg/L. The main mechanism for removing antibiotics was found to be biodegradation followed by adsorption. Paenarthrobacter was identified as the key genus in sulfonamides degradation, while Hydrogenophaga played a crucial role in tetracyclines degradation. Antibiotics resistant genes such as intI1, sul1, sul2, tetA, tetW and tetX were frequently detected in the effluent, with interception rates ranging from 105 - 106 copies/mL. The dominated microorganisms obtained in the study could potentially be utilized to enhance the capacity of biological processes for treating antibiotics contaminated wastewater. These findings contribute to a better understanding of BAF treating wastewater containing antibiotics and resistant genes.

Removal of antibiotic resistance genes in the breeding wastewater by the ferrate treatment at different sulfite concentrations

The investigation focused on the removal of antibiotic resistance genes from wastewater using ferrate treatment at various sulfite concentrations. As the sulfite concentration increased from 0 to 28.5 mg/L, the total DNA removal rate treated by 10 mg/L ferrate increased from 71.45% to 96.48%. The antibiotic resistance genes, save our souls genes and class I integron abundance reduction treated by ferrate ranged from 0.02 log to 1.66 log copies/ml at different sulfite concentrations, and the antibiotic resistance gene parC removal was enhanced as the sulfite addition. When the sulfite concentration reached to 28.5 mg/L, the catalase and superoxide dismutase levels were decreased by 21.57% and 10.04%, respectively, while the reactive oxygen species and lactate dehydrogenase levels were increased by 75.34% and 28.67%, respectively, compared to those in the wastewater treated by alone ferrate without sulfite. In the coupled ferrate (10 mg/L) and sulfite (28.5 mg/L) system, sulfate radicals and hydroxyl radicals were the main contributors to the DNA removals, and their contribution rates were 51.99% and 28.95%, respectively. The antibiotic resistance genes and save our souls genes hosts changes showed microbial community significantly affected the DNA removal. This study offers novel comprehensions on the antibiotic resistance genes removal from the wastewater by the combined ferrate and sulfite.