Accumulation of sulfonamide resistance genes and bacterial community function prediction in microbial fuel cell-constructed wetland treating pharmaceutical wastewater. - Related Documents




#
Rank
Similarity
Title + Abs.
Year
PMID
012345
789601.0000Accumulation of sulfonamide resistance genes and bacterial community function prediction in microbial fuel cell-constructed wetland treating pharmaceutical wastewater. Microbial fuel cell constructed wetlands (CW-MFCs) with different circuit operation conditions and hydraulic retention time (HRT) were constructed to evaluate their ability to remove and accumulate pharmaceutical and personal care products (PPCPs) (sulfadiazine (SDZ), carbamazepine (CBZ), naproxen (NPX) and ibuprofen (IBP)) during four months running process. The abundance level of corresponding sulfonamide antibiotic resistance genes (ARGs) was also investigated. The results showed that closed circuit operation of CW-MFC contributed to the decrease in mass loading of COD, NH(4)(+)-N, PPCPs, and wastewater toxicity in the effluent. Additionally, closed circuit operation with low HRT contributed to enhancing selected PPCP mass accumulation on electrodes by electro-adsorption, and thus the higher sulfonamide ARG abundance was detected in the electrodes and effluent. Moreover, the composition of bacteria was greatly influenced by the mass accumulation of PPCPs revealed by redundancy analysis results. Procrustes analysis results further demonstrated that bacterial community contributed greatly to the ARGs profiles. Therefore, ARGs with their host bacteria revealed by network analysis were partially deposited on electrode substrates, and thus ARGs were effectively accumulated on electrodes. Function analysis of the bacterial community from PICRUSt predicted metagenomes revealed that closed circuit mode enhanced the abundances of the function genes of metabolic and the multiple ARGs, suggesting that closed circuit operation exhibited positive effects on metabolic process and ARG accumulation in CW-MFC system.202031995737
789810.9997Effects of graphite and Mn ore media on electro-active bacteria enrichment and fate of antibiotic and corresponding resistance gene in up flow microbial fuel cell constructed wetland. This study assessed the influence of substrate type on pollutants removal, antibiotic resistance gene (ARG) fate and bacterial community evolution in up-flow microbial fuel cell constructed wetlands (UCW-MFC) with graphite and Mn ore electrode substrates. Better COD removal and higher bacterial community diversity and electricity generation performance were achieved in Mn ore constructed UCW-MFC (Mn). However, the lower concentration of sulfadiazine (SDZ) and the total abundances of ARGs were obtained in the effluent in the graphite constructed UCW-MFC (s), which may be related to higher graphite adsorption and filter capacity. Notably, both reactors can remove more than 97.8% of ciprofloxacin. In addition, significant negative correlations were observed between SDZ, COD concentration, ARG abundances and bacterial a-diversity indices. The LEfse analysis revealed significantly different bacterial communities due to the substrate differences in the two reactors, and Geobacter, a typical model electro-active bacteria (EAB), was greatly enriched on the anode of UCW-MFC (Mn). In contrast, the relative abundance of methanogens (Methanosaeta) was inhibited. PICRUSt analysis results further demonstrated that the abundance of extracellular electron transfer related functional genes was increased, but the methanogen function genes and multiple antibiotic resistance genes in UCW-MFC (Mn) anode were reduced. Redundancy analyses indicated that substrate type, antibiotic accumulation and bacterial community were the main factors affecting ARGs. Moreover, the potential ARG hosts and the co-occurrence of ARGs and intI1 were revealed by network analysis.201931442759
790420.9996Effect of the coexposure of sulfadiazine, ciprofloxacin and zinc on the fate of antibiotic resistance genes, bacterial communities and functions in three-dimensional biofilm-electrode reactors. Three-dimensional biofilm electrode reactors (3D-BERs) with high treatment efficiency were constructed to treat wastewater containing sulfadiazine (SDZ) and ciprofloxacin (CIP) coexposure with Zinc (Zn). The results showed that coexposure to target antibiotics and Zn increased the absolute and relative abundances of target antibiotic resistance genes (ARGs). Additionally, the target ARG abundances were higher on cathode of 3D-BER compared with ordinary anaerobic reactor while the abundances of total ARGs were decreased in the effluent. Meanwhile, redundancy analysis results revealed that the composition of bacteria carrying ARGs was greatly influenced in the cathode by the accumulation of Zn and antibiotic, which dominated the changes of ARG abundances. Additionally, ARGs with their host bacteria revealed by network analysis were partially deposited on electrode substrates when being removed from wastewater. Thus, 3D-BER exhibits capability of simultaneously eliminating antibiotic and Zn, and greatly reduces the risks of ARGs spread.202031677404
789730.9996Enhanced 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
790240.9995Determination of the lower limits of antibiotic biodegradation and the fate of antibiotic resistant genes in activated sludge: Both nitrifying bacteria and heterotrophic bacteria matter. Antibiotics can be biodegraded in activated sludge via co-metabolism and metabolism. In this study, we investigated the biodegradation pathways of sulfamethoxazole (SMX) and antibiotic resistant genes' (ARGs) fate in different autotrophic and heterotrophic microorganisms, by employing aerobic sludge, mixed sludge, and nitrifying sludge. A threshold concentration of SMX activating the degradation pathways in the initial stage of antibiotics degradation was found and proved in different activated sludge systems. Heterotrophic bacteria played an important role in SMX biodegradation. However, ammonia-oxidizing bacteria (AOB) had a faster metabolic rate, which was about 15 times higher than heterotrophic bacteria, contributing much to SMX removal via co-metabolism. As SMX concentration increases, the amoA gene and AOB relative abundance decreased in aerobic sludge due to the enrichment of functional heterotrophic bacteria, while it increased in nitrifying sludge. Microbial community analysis showed that functional bacteria which possess the capacity of SMX removal and antibiotic resistance were selected by SMX pressure. Potential ARGs hosts could increase their resistance to the biotoxicity of SMX and maintain system performance. These findings are of practical significance to guide antibiotic biodegradation and ARGs control in wastewater treatment plants.202234799165
790050.9995Biochar-amended constructed wetlands enhance sulfadiazine removal and reduce resistance genes accumulation in treatment of mariculture wastewater. With the rapid development of mariculture, an increasing amount of antibiotics are being discharged into the marine environment. Effectively removing antibiotics and antibiotic resistance genes (ARGs) in mariculture wastewater with a relatively high salinity and low C/N presents challenges. Biochar-amended constructed wetlands (CWs) can effectively remove antibiotics, However, few studies have compared the impacts of biochar-amended CWs pyrolyzed at different temperatures on the treatment of mariculture wastewater. Thus, this study utilized biochar prepared at three temperatures as substrate for CWs (CW-300, CW-500, and CW-700), aiming to evaluate their efficiency to treat mariculture wastewater containing antibiotic sulfadiazine (SDZ). The results demonstrated that compared to traditional quartz sand-filled CW (NCW), the addition of biochar with a larger specific surface area significantly enhanced the removal efficiency of SDZ by 21.72%-46.96%. Additionally, the addition of biochar effectively reduced the relative abundance of one integron gene (int1) and antibiotic resistance genes (ARGs) including sul1, sul2, and sul3 in both effluent and substrates. The addition of biochar reduced the accumulation of extracellular polymeric substances within the substrate of CWs, thereby mitigating the proliferation and spread of ARGs. The microbial community structure indicated that the addition of biochar increased the abundance of the potential antibiotic-degrading bacteria such as Proteobacteria and Bacteroidota, facilitating the degradation of SDZ and mitigating the accumulation of ARGs. This study demonstrated that biochar can be a promising substrate in CWs for treating mariculture wastewater containing antibiotics.202539986428
790360.9995Effects of zero-valent iron (ZVI) on nitrogen conversion, transformation of sulfamethoxazole (SMX) and abundance of antibiotic resistance genes (ARGs) in aerobic granular sludge process. Even after pre-treatment, livestock and poultry wastewater still contain high concentrations of ammonia and residual antibiotics. These could be removed economically using the aerobic granular sludge (AGS) process with zero-valent iron (ZVI). The interaction of antibiotics and nitrogen in this process needs to be clarified and controlled, however, to achieve good removal performance. Otherwise, antibiotics might generate transformation products (TPs) with higher toxicity and lead to the emergence of antibiotic-resistant bacteria carrying antibiotic resistance genes (ARGs), which could cause persistent toxicity and the risk of disease transmission to the ecological environment. This study investigated the impact of ZVI on AGS for nitrogen and sulfamethoxazole (SMX) removal. The results show that AGS could maintain good ammonia removal performance and that the existence of SMX had a negative impact on ammonia oxidation activities. ZVI contributed to an increase in the abundance of nitrite oxidation bacteria, denitrifying bacteria and the functional genes of nitrogen removal. This led to better total nitrogen removal and a decrease in N(2)O emission. Accompanied by biological nitrogen transformation, SMX could be transformed into 14 TPs through five pathways. ZVI has the potential to enhance transformation pathways with TPs of lower ecotoxicity, thereby reducing the acute and chronic toxicity of the effluent. Unfortunately, ZVI might enhance the abundance of sul1, sul2, and sul3 in AGS, which increases the risk of sulfonamide antibiotic resistance. In AGS, Opitutaceae, Xanthomonas, Spartobacteria and Mesorhizobium were potential hosts for ARGs. This study provides theoretical references for the interaction of typical antibiotics and nitrogen in the biological treatment process of wastewater and bioremediation of natural water bodies.202337832300
790170.9995Responses of antibiotic resistance genes and microbial community in the microalgae-bacteria system under sulfadiazine: Mechanisms and implications. Microalgae-bacteria system is an emerging alternative for sustainable wastewater treatment. Exploring the structure and diversity of microbial community in microalgae-bacteria system under sulfadiazine stress can contribute to the understanding of the sulfadiazine behavior in environments. Furthermore, as important carriers of antibiotic resistance genes (ARGs), microalgae can influence the profiles of ARGs either directly or indirectly through the secretion of metabolites. However, the effects of sulfadiazine on ARGs dissemination of microalgae-bacteria systems remain underreported. Herein, the impacts of sulfadiazine (1 mg/L) on the structural diversity and metabolic activity of microorganisms were examined in microalgae-bacteria systems. Results showed that microalgae-bacteria system could remove NH(4)(+)-N better (about 72.3 %) than activated sludge system, and hydrolysis was the first step in sulfadiazine degradation. A high level of intI1 (5.7 × 10(4) copies/mL) was detected in the initial media of the microalgae-bacteria system. Microalgae could hamper the rate of horizontal gene transfer activation. Compared with activated sludge system, the abundance of sul genes (sul1, sul2, sul3, and sulA) was significantly lowered after treating with microalgae-bacteria system. Additionally, the number of proteins and the sum of polysaccharides in the extracellular polymeric substances of the activated sludge system were lower than those of the microalgae-bacteria system. Microalgae can alter microbial communities. The genus Rozellomycota predominated all samples. Fungi with relatively high abundance increased in the microalgae-bacteria system, including Dipodascaceae, Rhodotorula, and Geotrichum. These results offer valuable insights into the application processes involving microalgae-bacteria system.202540602895
859280.9995Effects of persulfate treatment on the fates of antibiotic resistance genes in waste activated sludge fermentation process and the underlying mechanism. The occurrence of antibiotic resistance genes (ARGs) in waste activated sludge (WAS) fermentation was investigated with persulfate (PS)-based treatment. ARGs affiliated with multidrug (mexP), macrolide (bla(OXA-129)), tetracycline (tetB), sulfonamide (sul1), and vancomycin (vanRG) types were significantly decreased by PS/Fe treatment. Mechanistic investigations revealed that PS/Fe possessed oxidating potential and exhibited devastating effects on WAS fermentation. First, PS/Fe promoted cell structure damage, which facilitated ARGs release from potential hosts. A co-occurrence network analysis indicated that Fe/PS suppressed the proliferation of potential host bacteria. In addition, the PS/Fe treatment induced the decreased abundance of certain functional genes involved in pathways associated with ARGs dissemination. Finally, variation partitioning analysis demonstrated that the microbial community structure exhibited more vital effects on ARGs fates than physicochemical factors (i.e., pH and ORP) and gene expression (i.e., two-component system). This work provided a deeper understanding of the critical factors used to determine ARGs fates during WAS fermentation.202234864181
755090.9995Evaluating the effects of activated carbon on methane generation and the fate of antibiotic resistant genes and class I integrons during anaerobic digestion of solid organic wastes. The effects of activated carbon (AC) on methane production and the fate of antibiotic resistance genes (ARGs) were evaluated through comparing the anaerobic digestion performance and transformation of ARGs among anaerobic mono-digestion of food waste, co-digestion of food waste and chicken manure, and co-digestion of food waste and waste activated sludge. Results showed that adding AC in anaerobic digesters improved methane yield by at least double through the enrichment of bacteria and archaea. Conventional digestion process showed ability in removing certain types of ARGs, such as tetA, tetX, sul1, sul2, cmlA, floR, and intl1. Supplementing AC in anaerobic digester enhanced the removal of most of the ARGs in mono-digestion of food waste. The effects tended to be minimal in co-digestion of co-substrates such as chicken manure and waste activated sludge, both of which contain a certain amount of antibiotics.201829096147
7905100.9994Long-term responses of antibiotic resistance genes under high concentration of enrofloxacin, sulfadiazine and triclosan in aerobic granular sludge system. It is worth to reveal the long-term responses of antibiotic resistance genes (ARGs) in aerobic granular sludge (AGS) system exposed to high level enrofloxacin (ENR), sulfadiazine (SDZ) and triclosan (TCS). In present study, ppm level ENR, SDZ and TCS were added into three AGS reactors, respectively. ARGs in ENR and SDZ systems showed trends of increasing first and then decreasing, which were contrary to that in TCS system. 80%, 56% and 40% ARGs in ENR, SDZ and TCS systems, respectively, were enriched after loading, but several ARGs still kept high enrichment values after the withdrawn of loadings. The dominant bacteria in ENR (Flavobacterium), SDZ (Candidatus_Competibacter and Defluviicoccus) and TCS (Defluviicoccus) systems might contribute to the reductions of ARGs. IntI1 altered the overall ARGs profiles through horizontal gene transfer. The interactions of bacterial communities and environmental factors might be responsible for the different ARGs patterns in ENR, SDZ and TCS systems.202032470826
7543110.9994Aerobic granular sludge for swine wastewater treatment: Implications for antibiotic and antibiotic resistance gene elimination. Swine wastewater (SW) contains high levels of traditional pollutants, antibiotics, and antibiotic resistance genes (ARGs), necessitating effective elimination. Two parallel aerobic granular sludge (AGS) reactors, R(1) and R(2), were constructed and optimized for treating SW from two pig farms, identified as SW(1) and SW(2). R(2) showed higher antibiotic removal efficiency, particularly in the removal of sulfonamides, while fluoroquinolones tended to adsorb onto the sludge. Process optimization by introducing an additional anoxic phase enhanced denitrification and reduced effluent ARG levels, also aiding in the improved removal of fluoroquinolones. The nitrite-oxidizing bacteria (NOB) Nitrospira accumulated after the treatment process, reaching 12.8 % in R(1) and 14.1 % in R(2), respectively. Mantel's test revealed that pH, NH(4)(+)-N, and Mg significantly affected ARGs and microbial community. Sulfadiazine and sulfamethazine were found to significantly impact ARGs and the microbial communities. This study provides innovative insights into the application of AGS for the treatment of real SW.202439153702
7553120.9994Does the biological treatment or membrane separation reduce the antibiotic resistance genes from swine wastewater through a sequencing-batch membrane bioreactor treatment process. Swine wastes are the reservoir of antibiotic resistance genes (ARGs), which can potentially spread from swine farms to the environment. This study establishes a sequencing-batch membrane bioreactor (SMBR) for ARG removal from swine wastewater, and analyzes the effect of biological treatment and membrane separation on the ARG removal at different solid retention times (SRTs). The SMBR removed 2.91 logs (copy number) of ARGs at a short SRT (12 days). Raising the SRT reduced the removal rates of the detected genes by the biological treatment. Under the relative long SRT (30 days), ARGs and mobile genetic elements (MGEs) were maximized within the reactor and were well removed by membrane separation, with the average genes removal rate of 2.95 (copy number) and 1.18 logs (abundance). At the relatively low SRT, the biological treatment showed the dominant ARG removal effect, while the membrane separation took the advantages of ARG removal especially at the relatively long SRT. The ARG profile was related to the shift of the microbial community structure. The ARGs coexisted with the functional bacteria (ammonia oxidizing bacteria, nitrite oxidizing bacteria and denitrifiers), suggesting they are hosted by the functional bacteria.201829906721
8061130.9994The addition of nano zero-valent iron during compost maturation effectively removes intracellular and extracellular antibiotic resistance genes by reducing the abundance of potential host bacteria. Applying compost to soil may lead to the spread of antibiotic resistance genes (ARGs) in the environment. Therefore, removing ARGs from compost is critical. In this study, for the first time, nano zero-valent iron (nZVI) was added to compost during the maturation stage to remove ARGs. After adding 1 g/kg of nZVI, the abundance of total intracellular and total extracellular ARGs was decreased by 97.62% and 99.60%, and that of total intracellular and total extracellular mobile genetic elements (MGEs) was decreased by 92.39% and 99.31%, respectively. A Mantel test and network analysis indicated that the reduction in potential host bacteria and intI1 after nZVI treatment promoted the removal of intracellular and extracellular ARGs. The addition of nZVI during composting reduced the horizontal transfer of ARGs and improve the total nitrogen and germination index of compost, allowing it to meet the requirements for organic fertilizers.202337352990
8567140.9994System-dependent divergence of microbial community and resistome in two anaerobic niches under sulfamethoxazole selection. The prevalence of sulfamethoxazole (SMX) in high-strength wastewater poses a significant threat to the stability and efficiency of anaerobic biological treatment systems, particularly when deployed as initial treatment units. However, the complex interactions arising from SMX biodegradation and their resultant effects on typical anaerobic digestion (AD) and sulfate-reducing (SR) systems are not thoroughly understood. This study revealed that SMX exposure stimulated methanogenesis in the AD system and sulfate reduction in the SR system, driven primarily by enriched key functional taxa (e.g., methanogens, sulfate-reducing bacteria). Organic matter removal efficiency increased significantly in the AD system under SMX stress, attributed to the enrichment of fermentative bacteria. Notably, the enriched class Actinomycetes was capable of SMX biodegradation, thereby likely mitigating SMX stress for other microorganisms. In contrast, the SR system exhibited significantly diminished organic matter removal despite developing a more functionally specialized community under SMX exposure. This community harbored fewer SMX degraders, perpetuating selective pressure on the microbiota. Increasing SMX concentrations failed to induce significant shifts in overall community structure in either system, while significantly promoted the proliferation of antibiotic resistance genes (ARGs), particularly pronounced in the SR system exhibiting high SMX accumulation. Moreover, mobile genetic elements mediated the horizontal transfer of the sulfonamide resistance gene sul1 and other co-occurring ARGs located on plasmids. This study provides novel insights into the convergent and divergent microbial responses in the AD and SR systems under SMX exposure, highlighting the dual effects (both stimulatory and inhibitory) of SMX on the functionality of these anaerobic systems.202541130171
7566150.9994Antibiotic sulfadiazine degradation by persulfate oxidation: Intermediates dependence of ecotoxicity and the induction of antibiotic resistance genes. To preserve the water resources, this study has analyzed the ecotoxicity and antibiotic resistance genes (ARGs) induction capacity of sulfadiazine degradation intermediates resulting from persulfate activation oxidation enhanced by ultraviolet, ultrasound and microwave. The five degradation pathways caused by the contribution discrepancy of electron transfer and singlet oxygen ((1)O(2)) and variations in the ecotoxicity of different degradation products were analyzed. Microcosm experiment exhibited that the microbial community in actual water changed significantly with SDZ and degradation intermediates, in which the dominant genera were Aeromonas, Cupriavidus, Elizabethkingia and Achromobacter. Except for the selective pressure on bacteria, the degradation intermediates also exert a certain degree or even stronger induction on sulfonamide ARGs (sul4, sul1 and sul2) than SDZ. Furthermore, the potential hosts for sulfonamide ARGs were revealed by network analysis. These results provide a better understanding of antibiotics degradation mechanism and ARGs occurrence, which is useful for controlling the spread of ARGs.202336372382
7579160.9994Shifting interactions among bacteria, fungi and archaea enhance removal of antibiotics and antibiotic resistance genes in the soil bioelectrochemical remediation. BACKGROUND: Antibiotics and antibiotic resistance genes (ARGs) are two pollutants in soil, especially ARGs as one of the top three threats to human health. The performance of soil microbial fuel cells (MFCs) fuelled with antibiotics was investigated. RESULTS: In this study, soil MFCs spiked with tetracycline exhibited optimal bioelectricity generation, which was 25% and 733% higher than those of MFCs spiked with sulfadiazine and control, respectively. Compared with the non-electrode treatment, not only did functional micro-organisms change in open- and closed-circuit treatments, but also the microbial affinities, respectively, increased by 50% and 340% to adapt to higher removal of antibiotics. For the open-circuit treatment, the ineffective interspecific relation of micro-organisms was reduced to assist the removal efficiency of antibiotics by 7-27%. For the closed-circuit treatment, an intensive metabolic network capable of bioelectricity generation, degradation and nitrogen transformation was established, which led to 10-35% higher removal of antibiotics. Importantly, the abundances of ARGs and mobile genetic element (MGE) genes decreased after the introduction of electrodes; especially in the closed-circuit treatment, the highest reduction of 47% and 53% was observed, respectively. CONCLUSIONS: Soil MFCs possess advantages for the elimination of antibiotics and ARGs with sevenfold to eightfold higher electricity generation than that of the control treatment. Compared with sulphonamides, the enhancement removal of tetracycline is higher, while both potential ARG propagation risk is reduced in soil MFCs. This study firstly synchronously reveals the relationships among bacteria, fungi and archaea and with ARGs and MGE genes in soil bioelectrochemical systems.201931249623
7551170.9994Microbial community evolution and fate of antibiotic resistance genes during sludge treatment in two full-scale anaerobic digestion plants with thermal hydrolysis pretreatment. Anaerobic digestion (AD) with thermal hydrolysis pretreatment is widely used as an efficient sludge treatment nowadays. However, the evolution of microbial community (especially for the archaea community), the fate of antibiotic resistance genes (ARGs), and their associations during such process in full-scale sludge treatment plants are rarely reported. Therefore, these scientific questions were explored at two full-scale sludge treatment plants through high-throughput sequencing and quantitative PCR. Results showed that Methanobacterium and Methanosphaera were the dominant archaea in thermal hydrolyzed sludge. The predominant bacteria in the sludge first shifted from nutrients removal functional bacteria to spore-forming bacteria after thermal hydrolysis, and then shifted to fermentative bacteria after AD. The full-scale plants could select ermB, ermF, mefA/E, qnrS and tetM. Though the bacteria and archaea biomass and community largely influenced the fate of ARGs, multiple linear regression analysis showed that the total ARGs were mainly affected by mobile genetic elements (MGEs).201931158777
7912180.9994Distinct effects of hypochlorite types on the reduction of antibiotic resistance genes during waste activated sludge fermentation: Insights of bacterial community, cellular activity, and genetic expression. The effectiveness of hypochlorites (NaClO and Ca(ClO)(2)) on the reduction of antibiotic resistance genes (ARGs) during waste activated sludge (WAS) fermentation was determined by the quantitative PCR. NaClO and Ca(ClO)(2) exhibited distinct effects on ARGs fates. Ca(ClO)(2) was effective in removing all investigated ARGs, and the efficiency was highly dose-dependent. Unexpectedly, the NaClO treatment attenuated ARGs with lower efficiency and even caused the propagation of certain ARGs (i.e., aadA1 and tetQ) at higher doses. The extracellular polymeric substances dissolution and membrane integrity suggested that unstable NaClO had acute effects on bacteria initially, while it was ineffective to further attenuate ARGs released from hosts due to the rapid consumption of oxidative ClO(-). Without lasting and strong oxidative stress, the microbial activities of tolerant ARGs hosts will partially recover and then contribute to the ARGs dissemination across genera. In contrast, solid-state Ca(ClO)(2) was slowly released and exhibited prolonged effects on bacteria by disrupting cell membranes and removing the susceptible ARGs released from hosts. Furthermore, bacterial taxa-ARG network analysis indicated that Ca(ClO)(2) reduced the abundance of potential hosts, and the metabolic pathway and gene expression related to ARGs propagation were significantly downregulated by Ca(ClO)(2), which contributed to efficient ARGs attenuation.202133265039
7597190.9994Metagenomic analysis reveals the effects of long-term antibiotic pressure on sludge anaerobic digestion and antimicrobial resistance risk. Continuous stirred-tank digesters with tetracyclines and sulfonamides were operated to investigate the impacts of antibiotic pressure on sludge anaerobic digestion. The versatile methanogen Methanosarcinales and strictly hydrogenotrophic methanogen Methanobacteriales increased and decreased by 21.1% and 10.9% under antibiotic pressure, respectively. KEGG analysis revealed that hydrogenotrophic and acetoclastic methanogenesis pathways were all affected. The decrease in abundance of function genes involved in lipid metabolism, carbohydrate metabolism, and fatty acid degradation, would lead to a reduction in methane production by 25%. Network analysis indicated positive associations among tetracycline residuals, abundance of resistance genes (ARGs), and specific member of potential hosts. Over 1000 ARG subtypes were widely detected in sludge, including macrolide (28%), tetracycline (24%), fluoroquinolone (20%), and peptide (20%) resistance genes. AD process exposed to long-term antibiotic would increase the diversity and abundance of ARG, enhance the association of ARG with specific microbes, and select bacteria able to perform chemotaxis mechanism.201930861447