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811700.9907Composting of oxytetracycline fermentation residue in combination with hydrothermal pretreatment for reducing antibiotic resistance genes enrichment. Hydrothermal pretreatment can efficiently remove the residual antibiotics in oxytetracycline fermentation residue (OFR), but its effect on antibiotic resistance genes (ARGs) during composting remains unclear. This study compared the shifts in bacterial community and evolutions in ARGs and integrons during different composting processes of OFRs with and without hydrothermal pretreatment. The results demonstrated that hydrothermal pretreatment increased the bacterial alpha diversity at the initial phase, and increased the relative abundances of Proteobacteria and Actinobacteria but decreased that of Bacteroidetes at the final phase by inactivating mycelia and removing residual oxytetracycline. Composting process inevitably elevated the abundance and relative abundance of ARGs. However, the increase in ARGs was significantly reduced by hydrothermal pretreatment, because the removal of oxytetracycline decreased their potential host bacteria and inhibited their horizontal gene transfer. The results demonstrated that hydrothermal pretreatment is an efficient strategy to reduce the enrichment of ARGs during the OFR composting.202033099099
794010.9906Microplastics affect the ammonia oxidation performance of aerobic granular sludge and enrich the intracellular and extracellular antibiotic resistance genes. Microplastics (MPs) and antibiotic resistance genes (ARGs), as emerging pollutants, are frequently detected in wastewater treatment plants, and their threats to the environment have received extensive attentions. However, the effects of MPs on the nitrification of aerobic granular sludge (AGS) and the spread patterns of intracellular and extracellular ARGs (iARGs and eARGs) in AGS were still unknown. In this study, the responses of AGS to the exposure of 1, 10 and 100 mg/L of typical MPs (polyvinyl chloride (PVC), polyamide (PA), polystyrene (PS) and polyethylene (PE)) and tetracycline were focused on in 3 L nitrifying sequencing batch reactors. 10 mg/L MPs decreased the nitrification function, but nitrification could recover. Furthermore, MPs inhibited ammonia-oxidizing bacteria and enriched nitrite-oxidizing bacteria, leading partial nitrification to losing stability. PVC, PA and PS stimulated the secretion of extracellular polymeric substances and reactive oxygen species. PE had less negative effect on AGS than PVC, PA and PS. The abundances of iARGs and eARGs (tetW, tetE and intI1) increased significantly and the intracellular and extracellular microbial communities obviously shifted in AGS system under MPs stress. Potential pathogenic bacteria might be the common hosts of iARGs and eARGs in AGS system and were enriched in AGS and MPs biofilms.202133387747
811120.9906Effect of alkaline-thermal pretreatment on biodegradable plastics degradation and dissemination of antibiotic resistance genes in co-compost system. Biodegradable plastics (BDPs) are an eco-friendly alternative to traditional plastics in organic waste, but their microbial degradation and impact on antibiotic resistance genes (ARGs) transmission during co-composting remain poorly understood. This study examines how alkaline-thermal pretreatment enhances BDPs degradation and influences the fate of ARGs and mobile genetic elements (MGEs) in co-composting. Pretreatment with 0.1 mol/L NaOH at 100℃ for 40 minutes increased the surface roughness and hydrophilicity of BDPs while reducing their molecular weight and thermal stability. Incorporating pretreated BDPs film (8 g/kg-TS) into the compost reduced the molecular weight of the BDPs by 59.70 % during the maturation stage, facilitating compost heating and prolonging the thermophilic stage. However, incomplete degradation of BDPs releases numerous smaller-sized microplastics, which can act as carriers for microorganisms, facilitating the dissemination of ARGs across environments and posing significant ecological and public health risks. Metagenomic analysis revealed that pretreatment enriched plastic-degrading bacteria, such as Thermobifida fusca, on BDPs surfaces and accelerated microbial plastic degradation during the thermophilic stage, but also increased ARGs abundance. Although pretreatment significantly reduced MGEs abundance (tnpA, IS19), the risk of ARGs dissemination remained. Three plastic-degrading bacteria (Pigmentiphaga sp002188465, Bacillus clausii, and Bacillus altitudinis) were identified as ARGs hosts, underscoring the need to address the risk of horizontal gene transfer of ARGs associated with pretreatment in organic waste management.202539970645
812330.9904The effect of bulk-biochar and nano-biochar amendment on the removal of antibiotic resistance genes in microplastic contaminated soil. Biochar amendment has significant benefits in removing antibiotic resistance genes (ARGs) in the soil. Nevertheless, there is little information on ARGs removal in microplastic contaminated soil. Herein, a 42-day soil microcosm experiment were carried out to study how two coconut shell biochars (bulk- and nano-size) eliminate soil ARGs with/without microplastic presence. The results showed that microplastic increased significantly the numbers and abundances of ARGs in soil at 14d of cultivation. And, two biochars amendment effectively inhibited soil ARGs spread whether or not microplastic was present, especially for nano-biochar which had more effective removal compared to bulk-biochar. However, microplastic weakened soil ARGs removal after applying same biochar. Two biochars removed ARGs through decreasing horizontal gene transfer (HGT) of ARGs, potential host-bacteria abundances, some bacteria crowding the eco-niche of hosts and promoting soil properties. The adverse effect of microplastic on ARGs removal was mainly caused by weakening mobile genetic elements (MGEs) removal, and by changing soil properties. Structural equation modeling (SEM) analysis indicated that biochar's effect on ARGs profile was changed by its size and microplastic presence through altering MGEs abundances. These results highlight that biochar amendment is still an effective method for ARGs removal in microplastic contaminated soil.202437907163
811040.9903Removal of chlortetracycline and antibiotic resistance genes in soil by earthworms (epigeic Eisenia fetida and endogeic Metaphire guillelmi). The impacts of two ecological earthworms on the removal of chlortetracycline (CTC, 0.5 and 15 mg kg(-1)) and antibiotic resistance genes (ARGs) in soil were explored through the soil column experiments. The findings showed that earthworm could significantly accelerate the degradation of CTC and its metabolites (ECTC) in soil (P < 0.05), with epigeic Eisenia fetida promoting degradation rapidly and endogeic Metaphire guillelmi exhibiting a slightly better elimination effect. Earthworms alleviated the abundances of tetR, tetD, tetPB, tetG, tetA, sul1, TnpA, ttgB and intI1 in soil, with the total relative abundances of ARGs decreasing by 35.0-44.2% in earthworm treatments at the 28th day of cultivation. High throughput sequencing results displayed that the structure of soil bacteria community was modified apparently with earthworm added, and some possible CTC degraders, Aeromonas, Flavobacterium and Luteolibacter, were promoted by two kinds of earthworms. Redundancy analysis demonstrated that the reduction of CTC residues, Actinobacteria, Acidobacteria and Gemmatimonadetes owing to earthworm stimulation was responsible for the removal of ARGs and intI1 in soil. Additionally, intI1 declined obviously in earthworm treatments, which could weaken the risk of horizontal transmission of ARGs. Therefore, earthworm could restore the CTC-contaminated soil via enhancing the removal of CTC, its metabolites and ARGs.202133798888
789350.9901Removal of ofloxacin and inhibition of antibiotic resistance gene spread during the aerobic biofilm treatment of rural domestic sewage through the micro-nano aeration technology. Micro-nano aeration (MNA) has great potential for emerging contaminant removal. However, the mechanism of antibiotic removal and antibiotic resistance gene (ARG) spread, and the impact of the different aeration conditions remain unclear. This study investigated the adsorption and biodegradation of ofloxacin (OFL) and the spread of ARGs in aerobic biofilm systems under MNA and conventional aeration (CVA) conditions. Results showed that the MNA increased OFL removal by 17.27 %-40.54 % and decreased total ARG abundance by 36.37 %-54.98 %, compared with CVA. MNA-induced biofilm rough morphology, high zeta potential, and reduced extracellular polymeric substance (EPS) secretion enhanced OFL adsorption. High dissolved oxygen and temperature, induced by MNA-enriched aerobic bacteria and their carrying OFL-degrading genes, enhanced OFL biodegradation. MNA inhibited the enrichment of ARG host bacteria, which acquired ARGs possibly via horizontal gene transfer (HGT). Functional profiles involved in the HGT process, including reactive oxygen species production, membrane permeability, mobile genetic elements (MGEs), adenosine triphosphate synthesis, and EPS secretion, were down-regulated by MNA, inhibiting ARG spread. Partial least-squares path modeling revealed that MGEs might be the main factor inhibiting ARG spread. This study provides insights into the mechanisms by which MNA enhances antibiotic removal and inhibits ARG spread in aerobic biofilm systems.202539733752
787360.9901Wheat straw pyrochar more efficiently decreased enantioselective uptake of dinotefuran by lettuce and dissemination of antibiotic resistance genes than hydrochar in an agricultural soil. Remediation of soils pollution caused by dinotefuran, a chiral pesticide, is indispensable for ensuring human food security. In comparison with pyrochar, the effect of hydrochar on enantioselective fate of dinotefuran, and antibiotic resistance genes (ARGs) profiles in the contaminated soils remain poorly understood. Therefore, wheat straw hydrochar (SHC) and pyrochar (SPC) were prepared at 220 and 500 °C, respectively, to investigate their effects and underlying mechanisms on enantioselective fate of dinotefuran enantiomers and metabolites, and soil ARG abundance in soil-plant ecosystems using a 30-day pot experiment planted with lettuce. SPC showed a greater reduction effect on the accumulation of R- and S-dinotefuran and metabolites in lettuce shoots than SHC. This was mainly resulted from the lowered soil bioavailability of R- and S-dinotefuran due to adsorption/immobilization by chars, together with the char-enhanced pesticide-degrading bacteria resulted from increased soil pH and organic matter content. Both SPC and SHC efficiently reduced ARG levels in soils, owing to lowered abundance of ARG-carrying bacteria and declined horizontal gene transfer induced by decreased dinotefuran bioavailability. The above results provide new insights for optimizing char-based sustainable technologies to mitigate pollution of dinotefuran and spread of ARGs in agroecosystems.202336996986
792670.9899Microplastics Exacerbated Conjugative Transfer of Antibiotic Resistance Genes during Ultraviolet Disinfection: Highlighting Difference between Conventional and Biodegradable Ones. Microplastics (MPs) have been confirmed as a hotspot for antibiotic resistance genes (ARGs) in wastewater. However, the impact of MPs on the transfer of ARGs in wastewater treatment remains unclear. This study investigated the roles and mechanisms of conventional (polystyrene, PS) and biodegradable (polylactic acid, PLA) MPs in the conjugative transfer of ARGs during ultraviolet disinfection. The results showed that MPs significantly facilitated the conjugative transfer of ARGs compared with individual ultraviolet disinfection, and PSMPs exhibited higher facilitation than PLAMPs. The facilitation effects were attributed to light shielding and the production of reactive oxygen species (ROS) and nanoplastics from ultraviolet irradiation of MPs. The light shielding of MPs protected the bacteria and ARGs from ultraviolet inactivation. More importantly, ROS and nanoplastics generated from irradiated MPs induced intracellular oxidative stress on bacteria and further increased the cell membrane permeability and intercellular contact, ultimately enhancing the ARG exchange. The greater fragmentation of PSMPs than PLAMPs resulted in a higher intracellular oxidative stress and a stronger enhancement. This study highlights the concerns of conventional and biodegradable MPs associated with the transfer of ARGs during wastewater treatment, which provides new insights into the combined risks of MPs and ARGs in the environment.202539723446
690780.9899Deciphering the impact of organic loading rate and digestate recirculation on the occurrence patterns of antibiotics and antibiotic resistance genes in dry anaerobic digestion of kitchen waste. Organic loading rate (OLR) is crucial for determining the stability of dry anaerobic digestion (AD). Digestate recirculation contributes to reactor stability and enhances methane production. Nevertheless, the understanding of how OLR and digestate recirculation affect the abundance and diversity of antibiotics and antibiotic resistance genes (ARGs), as well as the mechanisms involved in the dissemination of ARGs, remains limited. This study thoroughly investigated this critical issue through a long-term pilot-scale experiment. The metabolome analyses revealed the enrichment of various antibiotics, such as aminoglycoside, tetracycline, and macrolide, under low OLR conditions (OLR ≤ 4.0 g·VS/L·d) and the reactor instability. Antibiotics abundance decreased by approximately 19.66-31.69 % during high OLR operation (OLR ≥ 6.0 g·VS/L·d) with digestate recirculation. The metagenome analyses demonstrated that although low OLR promoted reactor stability, it facilitated the proliferation of antibiotic-resistant bacteria, such as Pseudomonas, and triggered functional profiles related to ATP generation, oxidative stress response, EPS secretion, and cell membrane permeability, thereby facilitating horizontal gene transfer (HGT) of ARGs. However, under stable operation at an OLR of 6.0 g·VS/L·d, there was a decrease in ARGs abundance but a notable increase in human pathogenic bacteria (HPB) and mobile genetic elements (MGEs). Subsequently, during reactor instability, the abundance of ARGs and HPB increased. Notably, during digestate recirculation at OLR levels of 6.0 and 7.0 g·VS/L·d, the process attenuated the risk of ARGs spread by reducing the diversity of ARGs hosts, minimizing interactions among ARGs hosts, ARGs, and MGEs, and weakening functional profiles associated with HGT of ARGs. Overall, digestate recirculation aids in reducing the abundance of antibiotics and ARGs under high OLR conditions. These findings provide advanced insights into how OLR and digestate recirculation affect the occurrence patterns of antibiotics and ARGs in dry AD.202438968733
811290.9899Fate of antibiotic resistance bacteria and genes during enhanced anaerobic digestion of sewage sludge by microwave pretreatment. The fate of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) were investigated during the sludge anaerobic digestion (AD) with microwave-acid (MW-H), microwave (MW) and microwave-H2O2-alkaline (MW-H2O2) pretreatments. Results showed that combined MW pretreatment especially for the MW-H pretreatment could efficiently reduce the ARB concentration, and most ARG concentrations tended to attenuate during the pretreatment. The subsequent AD showed evident removal of the ARB, but most ARGs were enriched after AD. Only the concentration of tetX kept continuous declination during the whole sludge treatment. The total ARGs concentration showed significant correlation with 16S rRNA during the pretreatment and AD. Compared with unpretreated sludge, the AD of MW and MW-H2O2 pretreated sludge presented slightly better ARB and ARGs reduction efficiency.201626970692
8125100.9898The removal performances and evaluation of heavy metals, antibiotics, and resistomes driven by peroxydisulfate amendment during composting. This study aimed to explore the effect of peroxydisulfate on the removal of heavy metals, antibiotics, heavy metal resistance genes (HMRGs), and antibiotic resistance genes (ARGs) during composting. The results showed that peroxydisulfate achieved the passivation of Fe, Mn, Zn, and Cu by promoting their speciation variations, thus reducing their bioavailability. And the residual antibiotics were better degraded by peroxydisulfate. In addition, metagenomics analysis indicated that the relative abundance of most HMRGs, ARGs, and MGEs was more effectively down-regulated by peroxydisulfate. Network analysis confirmed Thermobifida and Streptomyces were dominant potential host bacteria of HMRGs and ARGs, whose relative abundance was also effectively down-regulated by peroxydisulfate. Finally, mantel test showed the significant effect of the evolution of microbial communities and strong oxidation of peroxydisulfate on the removal of pollutants. These results suggested that heavy metals, antibiotics, HMRGs, and ARGs shared a joint fate of being removed driven by peroxydisulfate during composting.202337307729
7927110.9897Different microplastics distinctively enriched the antibiotic resistance genes in anaerobic sludge digestion through shifting specific hosts and promoting horizontal gene flow. Both microplastics (MPs) and antibiotic resistance genes (ARGs) are intensively detected in waste activated sludge (WAS). However, the distinctive impacts of different MPs on ARGs emergence, dissemination, and its potential mechanisms remain unclear. In this study, long-term semi-continuous digesters were performed to examine the profiles of ARGs and antibiotic-resistant bacteria (ARB) in response to two different typical MPs (polyethylene (PE) and polyvinyl chloride (PVC)) in anaerobic sludge digestion. Metagenomic results show that PE- and PVC-MPs increase ARGs abundance by 14.8% and 23.6% in digester, respectively. ARB are also enriched by PE- and PVC-MPs, Acinetobacter sp. and Salmonella sp. are the dominant ARB. Further exploration reveals that PVC-MPs stimulates the acquisition of ARGs by human pathogen bacteria (HPB) and functional microorganisms (FMs), but PE-MPs doesn't. Network analysis shows that more ARGs tend to co-occur with HBP and FMs after MPs exposure, and more importantly, new bacteria are observed to acquire ARGs possibly via horizontal gene flow (HGF) in MPs-stressed digester. The genes involved in the HGF process, including reactive oxygen species (ROS) production, cell membrane permeability, extracellular polymeric substances (EPS) secretion, and ATP synthesis, are also enhanced by MPs, thereby attributing to the promoted ARGs dissemination. These findings offer advanced insights into the distinctive contribution of MPs to fate, host, dissemination of ARGs in anaerobic sludge digestion.202336423550
8119120.9897Biochar-amended composting of lincomycin fermentation dregs promoted microbial metabolism and reduced antibiotic resistance genes. Improper disposal of antibiotic fermentation dregs poses a risk of releasing antibiotics and antibiotic resistant bacteria to the environment. Therefore, this study evaluated the effects of biochar addition to lincomycin fermentation dregs (LFDs) composting. Biochar increased compost temperature and enhanced organic matter decomposition and residual antibiotics removal. Moreover, a 1.5- to 17.0-fold reduction in antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) was observed. Adding biochar also reduced the abundances of persistent ARGs hosts (e.g., Streptomyces, Pseudomonas) and ARG-related metabolic pathways and genes (e.g., ATP-binding cassette type-2 transport, signal transduction and multidrug efflux pump genes). By contrast, compost decomposition improved due to enhanced metabolism of carbohydrates and amino acids. Overall, adding biochar into LFDs compost reduced the proliferation of ARGs and enhanced microbial community metabolism. These results demonstrate that adding biochar to LFDs compost is a simple and efficient way to decrease risks associated with LFDs composting.202336334868
6919130.9896Enhanced removal of antibiotic resistance genes during chicken manure composting after combined inoculation of Bacillus subtilis with biochar. This study explored the combined effects of Bacillus subtilis inoculation with biochar on the evolution of bacterial communities, antibiotic resistance genes (ARGs), and mobile genetic elements (MGEs) during the composting of chicken manure. The results showed that B. subtilis inoculation combined with biochar increased bacterial abundance and diversity as well as prolonged the compost thermophilic period. Promoted organic matter biodegradation and facilitated the organic waste compost humification process, reduced the proliferation of ARGs by altering the bacterial composition. Firmicutes and Actinobacteriota were the main resistant bacteria related to ARGs and MGEs. The decrease in ARGs and MGEs was associated with the reduction in the abundance of related host bacteria. Compost inoculation with B. subtilis and the addition of biochar could promote nutrient transformation, reduce the increase in ARGs and MGEs, and increase the abundance of beneficial soil taxa.202437778803
7937140.9896Effects of oxytetracycline on variation in intracellular and extracellular antibiotic resistance genes during swine manure composting. This research aimed to investigate the alterations in extracellular (eARGs) and intracellular (iARGs) antibiotic resistance genes in response to oxytetracycline (OTC), and unravel the dissemination mechanism of ARGs during composting. The findings revealed both low (L-OTC) and high contents (H-OTC) of OTC significantly enhanced absolute abundance (AA) of iARGs (p < 0.05), compared to CK (no OTC). Composting proved to be a proficient strategy for removing eARGs, while AA of eARGs was significantly enhanced in H-OTC (p < 0.05). OTC resulted in an increase in AA of mobile genetic elements (MGEs), ATP levels, antioxidant and DNA repair enzymes in bacteria in compost product. Structural equation model further demonstrated that OTC promoted bacterial DNA repair and antioxidant enzyme activities, altered bacterial community and enhanced MGEs abundance, thereby facilitating iARGs dissemination. This study highlights OTC can increase eARGs and iARGs abundance, underscoring the need for appropriate countermeasures to mitigate potential hazards.202438036151
8124150.9896Effect of graphene and graphene oxide on antibiotic resistance genes during copper-contained swine manure anaerobic digestion. Copper is an important selectors for antibiotic resistance genes (ARGs) transfer because of metal-antibiotic cross-resistance and/or coresistance. Due to carbon-based materials' good adsorption capacity for heavy metals, graphene and graphene oxide have great potential to reduce ARGs abundance in the environment with copper pollution. To figure out the mechanics, this study investigated the effects of graphene and graphene oxide on the succession of ARGs, mobile genetic elements (MGEs), heavy metal resistance genes (HMRGs), and bacterial communities during copper-contained swine manure anaerobic digestion. Results showed that graphene and graphene oxide could reduce ARGs abundance in varying degrees with the anaerobic reactors that contained a higher concentration of copper. Nevertheless, graphene decreased the abundance of ARGs more effectively than graphene oxide. Phylum-level bacteria such as Firmicutes, Bacteroidetes, Spirochaetes, and Verrucomicrobiaat were significantly positively correlated with most ARGs. Network and redundancy analyses demonstrated that alterations in the bacterial community are one of the main factors leading to the changes in ARGs. Firmicutes, Bacteroidetes, and Spirochaetes were enriched lower in graphene reactor than graphene oxide in anaerobic digestion products, which may be the main reason that graphene is superior to graphene oxide in reduced ARGs abundance. Additionally, ARGs were close to HMRGs than MGEs in the treatments with graphene, the opposite in graphene oxide reactors. Therefore, we speculate that the reduction of HMRGs in graphene may contribute to the result that graphene is superior to graphene oxide in reduced ARGs abundance in anaerobic digestion.202336394812
7929160.9895Size-dependent effects of microplastics on antibiotic resistance genes fate in wastewater treatment systems: The role of changed surface property and microbial assemblages in a continuous exposure mode. Microplastics (MPs) were continuously transported to wastewater treatment systems and accumulated in sludge constantly, potentially affecting systems function and co-occurrent contaminants fate. However, previous studies were based on acute exposure of MPs, which could not reflect the dynamics of MPs accumulation. Herein, this study firstly raised a more realistic method to evaluate the practical impacts of MPs on systems purification efficiency and antibiotic resistance genes (ARGs) fate. Continuous exposure of MPs did not pose negative effects on nutrients removal, but significantly changed the occurrence patterns of ARGs. ARGs abundances increased by 42.8 % and 54.3 % when exposed to millimeter-size MPs (mm-MPs) polyamide and polyethylene terephthalate, but increased by 31.3 % and 39.4 % to micron-size MPs (μm-MPs), respectively. Thus, mm-MPs posed severer effects on ARGs than μm-MPs. Further, mm-MPs surface properties were obviously altered after long-term exposure (higher specific surface area and O-containing species), which benefited microbes attachment. More importantly, more taxa linkages and changed topological properties (higher average degree and average weight) of co-occurrent network were observed in sludge with mm-MPs than with μm-MPs, as well as totally different potential host bacteria of ARGs. Rough surface of MPs and closer relations between ARGs and bacteria taxa contributed to the propagation of ARGs, which accounted for the observed higher ARGs abundances of mm-MPs. This study demonstrated that long-term accumulation of MPs in wastewater treatment systems affected ARGs fate, and mm-MPs caused severer risk due to their enrichment of ARGs. The results would promote the understanding of MPs real environmental behavior and influences.202236037899
6918170.9895Variations in antibiotic resistance genes and removal mechanisms induced by C/N ratio of substrate during composting. For a comprehensive insight into the potential mechanism of the removal of antibiotic resistance genes (ARGs) removal induced by initial substrates during composting, we tracked the dynamics of physicochemical properties, bacterial community composition, fungal community composition, the relative abundance of ARGs and mobile genetic genes (MGEs) during reed straw and cow manure composting with different carbon to nitrogen ratio. The results showed that the successive bacterial communities were mainly characterized by the dynamic balance between Firmicutes and Actinobacteria, while the fungal communities were composed of Ascomycota. During composting, the interactions between bacteria and fungi were mainly negative. After composting, the removal efficiency of ARGs in compost treatment with C/N ≈ 26 (LL) was higher than that in compost treatment with C/N ≈ 35 (HL), while MGEs were completely degraded in HL and enriched by 2.3% in LL. The large reduction in the relative abundance of ARGs was possibly due to a decrease in the potential host bacterial genera, such as Advenella, Tepidimicrobium, Proteiniphilum, Acinetobacter, Pseudomonas, Flavobacteria and Arcbacter. Partial least-squares path modeling (PLS-PM) revealed that the succession of bacterial communities played a more important role than MGEs in ARGs removal, while indirect factors of the fungal communities altered the profile of ARGs by affecting the bacterial communities. Both direct and indirect factors were affected by composting treatments. This study provides insights into the role of fungal communities in affecting ARGs and highlights the role of different composting treatments with different carbon to nitrogen ration on the underlying mechanism of ARGs removal.202134375241
8571180.9895Efficient elimination of antibiotics and antibiotic resistance genes in hyperthermophilic sludge composting. Composting is widely applied in recycling ever-increasing sewage sludge. However, the insufficient elimination of antibiotics and antibiotic resistance genes (ARGs) in conventional compost fertilizer poses considerable threat to agriculture safety and human health. Here we investigated the efficacy and potential mechanisms in the removal of antibiotics and ARGs from sludge in hyperthermophilic composting (HTC) plant. Our results demonstrated that the HTC product was of high maturity. HTC led to complete elimination of antibiotics and potential pathogens, as well as removal of 98.8 % of ARGs and 88.1 % of mobile genetic elements (MGEs). The enrichment of antibiotic-degrading candidates and related metabolic functions during HTC suggested that biodegradation played a crucial role in antibiotic removal. Redundancy analysis (RDA) and structural equation modelling (SEM) revealed that the reduction of ARGs was attributed to the decline of ARG-associated bacteria, mainly due to the high-temperature selection. These findings highlight the feasibility of HTC in sludge recycling and provide a deeper understanding of its mechanism in simultaneous removal of antibiotics and ARGs.202439217943
7939190.9895Metagenomic insights into the distribution, mobility, and hosts of extracellular antibiotic resistance genes in activated sludge under starvation stress. Extracellular antibiotic resistance genes (eARGs) are important emerging environmental pollutants in wastewater treatment plants (WWTPs). Nutritional substrate deficiency (i.e., starvation) frequently occurs in WWTPs owing to annual maintenance, water quality fluctuation, and sludge storage; and it can greatly alter the antibiotic resistance and extracellular DNA content of bacteria. However, the fate and corresponding transmission risk of eARGs in activated sludge under starvation stress remain largely unknown. Herein, we used metagenomic sequencing to explore the effects of starvation scenarios (carbon, nitrogen, and/or phosphorus deficiency) and environmental conditions (alternating anaerobic-aerobic, anaerobic, anoxic, and aerobic) on the distribution, mobility, and hosts of eARGs in activated sludge. The results showed that 30 days of starvation reduced the absolute abundances of eARGs by 40.9%-88.2%, but high-risk dual and multidrug resistance genes persisted. Starvation, particularly the simultaneous lack of carbon, nitrogen, and phosphorus under aerobic conditions, effectively alleviated eARGs by reducing the abundance of extracellular mobile genetic elements (eMGEs). Starvation also altered the profile of bacterial hosts of eARGs and the bacterial community composition, the latter of which had an indirect positive effect on eARGs via changing eMGEs. Our findings shed light on the response patterns and mechanisms of eARGs in activated sludge under starvation conditions and highlight starvation as a potential strategy to mitigate the risk of previously neglected eARGs in WWTPs.202337060877