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794000.9827Microplastics 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
788710.9821Double-edged sword effects of sulfate reduction process in sulfur autotrophic denitrification system: Accelerating nitrogen removal and promoting antibiotic resistance genes spread. This study proposed the double-edged sword effects of sulfate reduction process on nitrogen removal and antibiotic resistance genes (ARGs) transmission in sulfur autotrophic denitrification system. Excitation-emission matrix-parallel factor analysis identified the protein-like fraction in soluble microbial products as main endogenous organic matter driving the sulfate reduction process. The resultant sulfide tended to serve as bacterial modulators, augmenting electron transfer processes and mitigating oxidative stress, thereby enhancing sulfur oxidizing bacteria (SOB) activity, rather than extra electron donors. The cooperation between SOB and heterotroph (sulfate reducing bacteria (SRB) and heterotrophic denitrification bacteria (HDB)) were responsible for advanced nitrogen removal, facilitated by multiple metabolic pathways including denitrification, sulfur oxidation, and sulfate reduction. However, SRB and HDB were potential ARGs hosts and assimilatory sulfate reduction pathway positively contributed to ARGs spread. Overall, the sulfate reduction process in sulfur autotrophic denitrification system boosted nitrogen removal process, but also increased the risk of ARGs transmission.202439122125
811220.9820Fate 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
792630.9820Microplastics 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
787740.9815External circuit loading mode regulates anode biofilm electrochemistry and pollutants removal in microbial fuel cells. This study investigated the effects of different external circuit loading mode on pollutants removal and power generation in microbial fuel cells (MFC). The results indicated that MFC exhibited distinct characteristics of higher maximum power density (P(max)) (named MFC-HP) and lower P(max) (named MFC-LP). And the capacitive properties of bioanodes may affect anodic electrochemistry. Reducing external load to align with the internal resistance increased P(max) of MFC-LP by 54.47 %, without no obvious effect on MFC-HP. However, intermittent external resistance loading (IER) mitigated the biotoxic effects of sulfamethoxazole (SMX) (a persistent organic pollutant) on chemical oxygen demand (COD) and NH(4)(+)-N removal and maintained high P(max) (424.33 mW/m(2)) in MFC-HP. Meanwhile, IER mode enriched electrochemically active bacteria (EAB) and environmental adaptive bacteria Advenella, which may reduce antibiotic resistance genes (ARGs) accumulation. This study suggested that the external circuit control can be effective means to regulate electrochemical characteristics and pollutants removal performance of MFC.202439153696
811750.9813Composting 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
788060.9813The synergistic mechanism of β-lactam antibiotic removal between ammonia-oxidizing microorganisms and heterotrophs. Nitrifying system is an effective strategy to remove numerous antibiotics, however, the contribution of ammonia-oxidizing bacteria (AOB), ammonia-oxidizing archaea (AOA) and heterotrophs for antibiotic removal are still unclear. In this study, the mechanism of β-lactam antibiotic (cefalexin, CFX) removal was studied in a nitrifying sludge system. Results showed that CFX was synergistically removed by AOB (Nitrosomonas, played a major role) and AOA (Candidatus_Nitrososphaera) through ammonia monooxygenase-mediated co-metabolism, and by heterotrophs (Pseudofulvimonas, Hydrogenophaga, RB41, Thauera, UTCFX1, Plasticicumulans, Phaeodactylibacter) through antibiotic resistance genes (ARGs)-encoded β-lactamases-mediated hydrolysis. Regardless of increased archaeal and heterotrophic CFX removal with the upregulation of amoA in AOA and ARGs, the system exhibited poorer CFX removal performance at 10 mg/L, mainly due to the inhibition of AOB. This study provides new reference for the important roles of heterotrophs and ARGs, opening the possibilities for the application of ARGs in antibiotic biodegradation.202336174754
812370.9812The 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
785580.9811Combat against antibiotic resistance genes during photo-treatment of magnetic Zr-MOFs@Layered double hydroxide heterojunction: Conjugative transfer risk mitigating and bacterial inactivation. The dissemination of antimicrobial resistance (AMR) in wastewater treatment poses a severe threat to the global ecological environment. This study explored the effectiveness of photocatalysis in inactivating antibiotic resistant bacteria (ARB) and quantitatively clarified the inhibiting rate of the transfer of antibiotics resistance genes (ARGs). Herein, the magnetic heterojunction as UiO-66-NH(2)@CuFe LDH-Fe(3)O(4) (UN-66@LDH-Fe) effectively facilitated the electron-hole separation and accelerated the photogenerated charge transfer, thereby guaranteeing the stable practical application in aeration tanks. Notably, the internal electric field of heterogeneous photocatalyst resulted in significant increase of ARGs inactivation, achieving 5.63 log of ARB, 3.66 log of tetA and 3.57 log of Ampr genes were photodegraded under optimal reaction conditions within 6 h. Based on the complex microbial and molecular mechanism of multiple-ARB communities inactivation in photo-treatment, the photogenerated reactive oxygen species (ROSs, ·OH and ·O(2)(-)) effectively destroyed bacterial membrane protein, thereby the intracellular ROSs and redox cycles further induced oxidative stress, attributing to the abundance reduction of ARGs and their host bacteria. Moreover, long-term (7 days) continuous operation preliminarily verified the practical potential in reducing AMR spread and developing wastewater treatment efficacy. Overall, this study presented an advantageous synergistic strategy for mitigating the AMR-associated environmental risk in wastewater treatment.202540188541
782990.9810Insights into capture-inactivation/oxidation of antibiotic resistance bacteria and cell-free antibiotic resistance genes from waters using flexibly-functionalized microbubbles. The spread of antibiotic resistance in the aquatic environment severely threatens the public health and ecological security. This study investigated simultaneously capturing and inactivating/oxidizing the antibiotic resistant bacteria (ARB) and cell-free antibiotic resistance genes (ARGs) in waters by flexibly-functionalized microbubbles. The microbubbles were obtained by surface-modifying the bubbles with coagulant (named as coagulative colloidal gas aphrons, CCGAs) and further encapsulating ozone in the gas core (named as coagulative colloidal ozone aphrons, CCOAs). CCGAs removed 92.4-97.5% of the sulfamethoxazole-resistant bacteria in the presence of dissolved organic matter (DOM), and the log reduction of cell-free ARGs (particularly, those encoded in plasmid) reached 1.86-3.30. The ozone release from CCOAs led to efficient in-situ oxidation: 91.2% of ARB were membrane-damaged and inactivated. In the municipal wastewater matrix, the removal of ARB increased whilst that of cell-free ARGs decreased by CCGAs with the DOM content increasing. The ozone encapsulation into CCGAs reinforced the bubble performance. The predominant capture mechanism should be electrostatic attraction between bubbles and ARB (or cell-free ARGs), and DOM enhanced the sweeping and bridging effect. The functionalized microbubble technology can be a promising and effective barrier for ARB and cell-free ARGs with shortened retention time, lessened chemical doses and simplified treatment unit.202235063836
7927100.9810Different 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
7893110.9807Removal 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
7888120.9807Microecology of aerobic denitrification system construction driven by cyclic stress of sulfamethoxazole. The construction of aerobic denitrification (AD) systems in an antibiotic-stressed environment is a serious challenge. This study investigated strategy of cyclic stress with concentration gradient (5-30 mg/L) of sulfamethoxazole (SMX) in a sequencing batch reactor (SBR), to achieve operation of AD. Total nitrogen removal efficiency of system increased from about 10 % to 95 %. Original response of abundant-rare genera to antibiotics was changed by SMX stress, particularly conditionally rare or abundant taxa (CRAT). AD process depends on synergistic effect of heterotrophic nitrifying aerobic denitrification bacteria (Paracoccus, Thauera, Hypomicrobium, etc). AmoABC, napA, and nirK were functionally co-expressed with multiple antibiotic resistance genes (ARGs) (acrR, ereAB, and mdtO), facilitating AD process. ARGs and TCA cycling synergistically enhance the antioxidant and electron transport capacities of AD process. Antibiotic efflux pump mechanism played an important role in operation of AD. The study provides strong support for regulating activated sludge to achieve in situ AD function.202438710419
8124130.9807Effect 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
8487140.9807Mechanisms of nano zero-valent iron in enhancing dibenzofuran degradation by a Rhodococcus sp.: Trade-offs between ATP production and protection against reactive oxygen species. Nano zero-valent iron (nZVI) can enhance pollutants biodegradation, but it displays toxicity towards microorganisms. Gram-positive (G(+)) bacteria exhibit greater resistance to nZVI than Gram-negative bacteria. However, mechanisms of nZVI accelerating pollutants degradation by G(+) bacteria remain unclear. Herein, we explored effects of nZVI on a G(+) bacterium, Rhodococcus sp. strain p52, and mechanisms by which nZVI accelerates biodegradation of dibenzofuran, a typical polycyclic aromatic compound. Electron microscopy and energy dispersive spectroscopy analysis revealed that nZVI could penetrate cell membranes, which caused damage and growth inhibition. nZVI promoted dibenzofuran biodegradation at certain concentrations, while higher concentration functioned later due to the delayed reactive oxygen species (ROS) mitigation. Transcriptomic analysis revealed that cells adopted response mechanisms to handle the elevated ROS induced by nZVI. ATP production was enhanced by accelerated dibenzofuran degradation, providing energy for protein synthesis related to antioxidant stress and damage repair. Meanwhile, electron transport chain (ETC) was adjusted to mitigate ROS accumulation, which involved downregulating expression of ETC complex I-related genes, as well as upregulating expression of the genes for the ROS-scavenging cytochrome bd complex and ETC complex II. These findings revealed the mechanisms underlying nZVI-enhanced biodegradation by G(+) bacteria, offering insights into optimizing bioremediation strategies involving nZVI.202539549579
7853150.9807Natural pyrite and ascorbic acid co-enhance periodate activation for inactivation of antibiotic resistant bacteria and inhibition of resistance genes transmission: A green disinfection process dominated by singlet oxygen. The transmission of antibiotic resistance genes (ARGs) and the propagation of antibiotic resistant bacteria (ARB) threaten public health security and human health, and greener and more efficient disinfection technologies are expected to be discovered for wastewater treatment. In this study, natural pyrite and ascorbic acid (AA) were proposed as environmental-friendly activator and reductant for periodate (PI) activation to inactivate ARB. The disinfection treatment of PI/pyrite/AA system could inactivate 5.62 log ARB within 30 min, and the lower pH and higher PI and natural pyrite dosage could further boost the disinfection efficiency. The (1)O(2) and SO(4)(•-) were demonstrated to be crucial for the inactivation of ARB in PI/pyrite/AA system. The disinfection process destroyed the morphological structure of ARB, inducing oxidative stress and stimulating the antioxidant system. The PI/pyrite/AA system effectively reduced the intracellular and extracellular DNA concentration and ARGs abundance, inhibiting the propagation of ARGs. The presence of AA facilitated the activation of PI with natural pyrite and significantly increased the concentration of Fe(2+) in solution. The reusability of natural pyrite, the safety of the disinfection by-products and the inhibition of ARB regeneration indicated the application potential of PI/pyrite/AA system in wastewater disinfection.202439038380
7871160.9806Effects of different quaternary ammonium compounds on intracellular and extracellular resistance genes in nitrification systems under the pre-contamination of benzalkyl dimethylammonium compounds. As the harm of benzalkyl dimethylammonium compounds (BACs) on human health and environment was discovered, alkyltrimethyl ammonium compound (ATMAC) and dialkyldimethyl ammonium compound (DADMAC), which belong to quaternary ammonium compounds (QACs), were likely to replace BACs as the main disinfectants. This study simulated the iterative use of QACs to explore their impact on resistance genes (RGs) in nitrification systems pre-contaminated by BACs. ATMAC could initiate and maintain partial nitrification. DADMAC generated higher levels of reactive oxygen species and lactate dehydrogenase, leading to increased biological toxicity in bacteria. The abundance of intracellular RGs of sludge was higher with the stress of QACs. DADMAC also induced higher extracellular polymeric substance secretion. Moreover, it facilitated the transfer of RGs from sludge to water, with ATMAC disseminating RGs through si-tnpA-04 and DADMAC through si-intI1. Sediminibacterium might be potential hosts for RGs. This study offered insights into disinfectant usage in the post-COVID-19 era.202539612960
7897170.9806Enhanced removal of antibiotic and antibiotic resistance genes by coupling biofilm electrode reactor and manganese ore substrate up-flow microbial fuel cell constructed wetland system. Manganese ore substrate up-flow microbial fuel cell constructed wetland (UCW-MFC(Mn)) as an innovative wastewater treatment technology for purifying antibiotics and electricity generation with few antibiotic resistance genes (ARGs) generation has attracted attention. However, antibiotic purifying effects should be further enhanced. In this study, a biofilm electrode reactor (BER) that needs direct current driving was powered by a Mn ore anode (UCW-MFC(Mn)) to form a coupled system without requiring direct-current source. Removal efficiencies of sulfadiazine (SDZ), ciprofloxacin (CIP) and the corresponding ARGs in the coupled system were compared with composite (BER was powered by direct-current source) and anaerobic systems (both of BER and UCW-MFC were in open circuit mode). The result showed that higher antibiotic removal efficiency (94% for SDZ and 99.1% for CIP) in the coupled system was achieved than the anaerobic system (88.5% for SDZ and 98.2% for CIP). Moreover, electrical stimulation reduced antibiotic selective pressure and horizontal gene transfer potential in BER, and UCW-MFC further reduced ARG abundances by strengthening the electro-adsorption of ARG hosts determined by Network analysis. Bacterial community diversity continuously decreased in BER while it increased in UCW-MFC, indicating that BER mitigated the toxicity of antibiotic. Degree of modularity, some functional bacteria (antibiotic degrading bacteria, fermentative bacteria and EAB), and P450 enzyme related to antibiotic and xenobiotics biodegradation genes were enriched in electric field existing UCW-MFC, accounting for the higher degradation efficiency. In conclusion, this study provided an effective strategy for removing antibiotics and ARGs in wastewater by operating a BER-UCW-MFC coupled system.202337437616
7917180.9806Mechanisms of metabolic performance enhancement and ARGs attenuation during nZVI-assisted anaerobic chloramphenicol wastewater treatment. Anaerobic wastewater treatment is a promising technology for refractory pollutant treatment. The nano zero-valent iron (nZVI) assisted anaerobic system could enhance contaminant removal. In this work, we added nZVI into an anaerobic system to investigate the effects on system performances and metabolic mechanism for chloramphenicol (CAP) wastewater treatment. As nZVI concentrations increased from 0 to 1 g/L, the CAP removal efficiency was appreciably improved from 46.5% to 99.2%, while the CH(4) production enhanced more than 20 times. The enhanced CAP removal resulted from the enrichments of dechlorination-related bacteria (Hyphomicrobium) and other functional bacteria (e.g., Zoogloea, Syntrophorhabdus) associated with refractory contaminants degradation. The improved CH(4) production was ascribed to the increases in fermentative-related bacteria (Smithella and Acetobacteroides), homoacetogen (Treponema), and methanogens. The increased abundances of anaerobic functional genes further verified the mechanism of CH(4) production. Furthermore, the abundances of potential hosts of antibiotic resistance genes (ARGs) were reduced under high nZVI concentration (1 g/L), contributing to ARGs attenuation. This study provides a comprehensive analysis of the mechanism in metabolic performance enhancement and ARGs attenuation during nZVI-assisted anaerobic CAP wastewater treatment.202134323729
8119190.9805Biochar-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