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787200.9949Quaternary ammonium compounds promoted anoxic sludge granulation and altered propagation risk of intracellular and extracellular antibiotic resistance genes. Surfactants could influence sludge morphology and disinfectants were linked to antibiotic resistance genes (ARGs). Thus, the response of activated sludge and ARGs to long-term quaternary ammonium compounds (QACs) exposure required further investigation, which is a popular surfactant and disinfectant. Here, three sequencing batch reactors were fed with 5 mg/L most frequently detected QACs (dodecyl trimethyl ammonium chloride (ATMAC C12), dodecyl benzyl dimethyl ammonium chloride (BAC C12) and didodecyl dimethyl ammonium chloride (DADMAC C12)) for 180 d. The long-term inhibitory effect on denitrification ranked: DADMAC C12 > BAC C12 > ATMAC C12. Besides, obvious granular sludge promoted by the increase of α-Helix/(β-Sheet + Random coil) appeared in DADMAC C12 system. Moreover, intracellular ARGs increased when denitrification systems encountered QACs acutely but decreased in systems chronically exposed to QACs. Although replication and repair metabolism in ATMAC C12 system was higher, ATMAC C12 significantly promoted proliferation of extracellular ARGs. It was noteworthy that the propagation risk of extracellular ARGs in sludge increased significantly during sludge granulation process, and intracellular sul2 genes in sludge and water both increased with the granular diameter in DADMAC C12 system. The universal utilization of QACs may enhance antibiotic resistance of bacteria in wastewater treatment plants, deserving more attention.202336444811
853910.9939Effects of quaternary ammonium disinfectants on human pathogenic bacteria in anaerobic sludge digestion: Dose-response and resistance variation. Sewage sludge is a critical reservoir for biological pollutants, and its harmless disposal remains a major issue. Quaternary ammonium compounds (QACs) as typical household disinfectants are inevitably concentrated in sewage sludge, and have the potential to affect human pathogenic bacteria (HPBs) that remain poorly understood. This study found that the relative abundance of HPBs in digesters was decreased by 10 - 20 % at low QACs dose, but increased by 238 - 591 % at high QACs dose. Mechanistic analysis revealed that low QACs doses promoted functional hydrolytic/fermentative bacteria and their metabolism by stimulating extracellular polymeric substances secretion and enhancing resistance to QACs. Conversely, high QAC doses decreased microbial biomass and developed QACs and antibiotic resistance of HPBs by increasing cell membrane permeability and triggering oxidative stress, resulting in deteriorating sanitation performance. These findings provide advanced insights into the potential function and hazards of exogenous QACs on the biosafety of digestate.202539505280
774820.9938Bacillus subtilis reduces antibiotic resistance genes of animal sludge in vermicomposting by improving heat stress tolerance of Eisenia foetida and bacterial community adjustment. Antibiotic resistance genes (ARGs) in livestock industry have been recognized as a kind of pollutant. The effect of Bacillus subtilis (B. subtilis) as an additive for the reduction of ARGs in animal sludge from livestock and poultry wastewater treatment plant during vermicomposting was investigated. We also evaluated the oxidative stress level and growth of earthworms, Eisenia foetida, bacterial community succession, and the quality of the end products. Two treatments were conducted using B. subtilis, one at 18 °C and another at 28 °C. Controls were setup without the bacteria. The results showed that inoculation of B. subtilis promoted the degradation of organics at 28 °C and increased the germination index to 236%. The increased activities of the superoxide dismutase (1.69 U/mg pr) and catalase (8.05 U/mg pr) and the decreased activity of malondialdehyde (0.02 nmol/mg pr) by B. subtilis at 28 °C showed that the earthworms were relieved of heat stress. The addition of B. subtilis reduced the abundance of 32 target ARGs, including integron (intI-1), transposase (IS613) and resistant genes, such as sulfonamide (sul2), quinolone (oprJ), macrolide-lincosamide-streptogramin group B (ermF, ermB), tetracycline (tetL-02, tetX), β-lactama (blaOXA10-01) and aminoglycoside [strB, aac(6')-Ib(aka aacA4)-01, aac(6')-Ib(aka aacA4)-02]. Organic matter degrading Membranicola, Paludisphaera, Sphingorhabdus and uncultured bacterium belonging to the order Chitinophagales, nitrifying and nitrogen-fixing Singulisphaera and Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium, soil remediating Achromobacter, and plant growth promoting Kaistia, Galbibacter and Ilumatobacter were increased significantly (P < 0.05). However, the growth of harmful bacteria such as Burkholderiaceae was inhibited in the vermicompost. In earthworm guts, the probiotic Mesorhizobium was promoted, while the pathogenic uncultured bacterium belonging to the family Enterobacteriaceae was reduced. Besides, B. subtilis enhanced the host relationships between bacteria and ARGs. These findings might be helpful in the removal of ARGs in animal wastes and in understanding the synergy between earthworms and microorganisms.202336529325
789430.9938The fate and behavior mechanism of antibiotic resistance genes and microbial communities in flocs, aerobic granular and biofilm sludge under chloroxylenol pressure. Chloroxylenol (PCMX), an antibacterial agent, has been widely detected in water environment and has toxic effects on biology and ecology. During 270 d, the influence of PCMX on the performance of three nitrification systems was investigated, including floc-based sequencing batch reactor (FSBR), aerobic granule-based SBR (AGSBR) and biofilm SBR (BSBR). The nitrification capability of three systems was inhibited by PCMX, but recovered after domestication, and PCMX made three systems realize partial nitrification for 10, 100 and 35 days, respectively. The extracellular polymeric substances of three systems increased first and then decreased with the increment of PCMX. The granular structure of AGSBR may be conducive to the enrichment of antibiotic resistance genes (ARGs), and almost all ARGs of BSBR were reduced during the addition of 5.0 mg/L PCMX. The microbial community results showed that Rhodococcus as potential degrading bacteria was continuously enriched in three systems. Piscinibacter was regarded as the potential antibiotic resistant bacteria, which was positively associated with multiple ARGs in three systems. Additionally, quaternary ammonium compounds resistance genes had a variety of positive correlations with bacteria in three systems. This study provided a new perspective for the usage and treatment of PCMX.202235785744
674140.9937Benzyldimethyldodecyl ammonium chloride shifts the proliferation of functional genes and microbial community in natural water from eutrophic lake. Benzylalkyldimethylethyl ammonium compounds are pervasive in natural environments and toxic at high concentrations. The changes in functional genes and microbial diversity in eutrophic lake samples exposed to benzyldimethyldodecyl ammonium chloride (BAC) were assessed. BAC exerted negative effects on bacteria abundance, particularly at concentrations of 100 μg L(-1) and higher. A significant increase in the number of the quaternary ammonium compound-resistant gene qacA/B was recorded within the 10 μg L(-1) treatment after the first day of exposure. Not all antibiotic resistance genes increased in abundance as the concentrations of BAC increased; rather, gene abundances were dependent on the gene type, concentrations of BAC, and contact time. The nitrogen fixation-related gene nifH and ammonia monooxygenase gene amoA were inhibited by high concentrations of BAC after the first day, whereas an increase of the nitrite reductase gene nirK was stimulated by exposure. Microbial communities within higher treatment levels (1000 and 10 000 μg L(-1)) exhibited significantly different community composition compared to other treatment levels and the control. Selective enrichment of Rheinheimera, Pseudomonas, and Vogesella were found in the higher treatment levels, suggesting that these bacteria have some resistance or degradation capacity to BAC. Genes related with RNA processing and modification, transcription, lipid transport and metabolism, amino acid transport and metabolism, and cell motility of microbial community function were involved in the process exposed to the BAC stress.201829414358
720650.9936The treatment of wastewater containing pharmaceuticals in microcosm constructed wetlands: the occurrence of integrons (int1-2) and associated resistance genes (sul1-3, qacEΔ1). The aim of this study was to analyze the occurrence of sulfonamide resistance genes (sul1-3) and other genetic elements as antiseptic resistance gene (qacEΔ1) and class 1 and class 2 integrons (int1-2) in the upper layer of substrate and in the effluent of microcosm constructed wetlands (CWs) treating artificial wastewater containing diclofenac and sulfamethoxazole (SMX), which is a sulfonamide antibiotic. The bacteria in the substrate and in the effluents were equipped with the sul1-2, int1, and qacEΔ1 resistance determinants, which were introduced into the CW system during inoculation with activated sludge and with the soil attached to the rhizosphere of potted seedlings of Phalaris arundinacea 'Picta' roots (int1). By comparing the occurrence of the resistance determinants in the upper substrate layer and the effluent, it can be stated that they neither were lost nor emerged along the flow path. The implications of the presence of antibiotic resistance genes in the effluent may entail a risk of antibiotic resistance being spread in the receiving environment. Additionally, transformation products of SMX were determined. According to the obtained results, four (potential) SMX transformation products were identified. Two major metabolites of SMX, 2,3,5-trihydroxy-SMX and 3,5-dihydroxy-SMX, indicated that SMX may be partly oxidized during the treatment. The remaining two SMX transformation products (hydroxy-glutathionyl-SMX and glutathionyl-SMX) are conjugates with glutathione, which suggests the ability of CW bacterial community to degrade SMX and resist antimicrobial stress.201728493189
789960.9936Removal of sulfamethoxazole in an algal-bacterial membrane aerated biofilm reactor: Microbial responses and antibiotic resistance genes. Antibiotics are frequently detected in wastewater, but often are poorly removed in conventional wastewater treatment processes. Combining microalgal and nitrifying bacterial processes may provide synergistic removal of antibiotics and ammonium. In this research, we studied the removal of the antibiotic sulfamethoxazole (SMX) in two different reactors: a conventional nitrifying bacterial membrane aerated biofilm reactor (bMABR) and algal-bacterial membrane aerated biofilm reactor (abMABR) systems. We investigated the synergistic removal of antibiotics and ammonium, antioxidant activity, microbial communities, antibiotic resistance genes (ARGs), mobile genetic elements (MGEs), and their potential hosts. Our findings show that the abMABR maintained a high sulfamethoxazole (SMX) removal efficiency, with a minimum of 44.6 % and a maximum of 75.8 %, despite SMX inhibition, it maintained a consistent 25.0 % ammonium removal efficiency compared to the bMABR. Through a production of extracellular polymeric substances (EPS) with increased proteins/polysaccharides (PN/PS), the abMABR possibly allowed the microalgae-bacteria consortium to protect the bacteria from SMX inactivation. The activity of antioxidant enzymes caused by SMX was reduced by 62.1-98.5 % in the abMABR compared to the bMABR. Metagenomic analysis revealed that the relative abundance of Methylophilus, Pseudoxanthomonas, and Acidovorax in the abMABR exhibited a significant positive correlation with SMX exposure and reduced nitrate concentrations and SMX removal. Sulfonamide ARGs (sul1 and sul2) appeared to be primarily responsible for defense against SMX stress, and Hyphomicrobium and Nitrosomonas were the key carriers of ARGs. This study demonstrated that the abMABR system has great potential for removing SMX and reducing the environmental risks of ARGs.202539423786
673570.9935Increased expression of antibiotic-resistance genes in biofilm communities upon exposure to cetyltrimethylammonium bromide (CTAB) and other stress conditions. Quaternary ammonium compounds (QAC, e.g., cetyltrimethylammonium bromide, (CTAB)) are widely used as surfactants and disinfectants. QAC already are commonly found in wastewaters, and their concentration could increase, since QAC are recommended to inactivate the SARS-CoV-2 (COVID-19) virus. Exposure of bacteria to QAC can lead to proliferation of antibiotic resistance genes (ARG). In particular, O(2)-based membrane biofilm reactors (O(2)-MBfRs) achieved excellent CTAB biodegradation, but ARG increased in their biofilms. Here, we applied meta-transcriptomic analyses to assess the impacts of CTAB exposure and operating conditions on microbial community's composition and ARG expression in the O(2)-MBfRs. Two opportunistic pathogens, Pseudomonas aeruginosa and Stenotrophomonas maltophilia, dominated the microbial communities and were associated with the presence of ARG. Operating conditions that imposed stress on the biofilms, i.e., limited supplies of O(2) and nitrogen or a high loading of CTAB, led to large increases in ARG expression, particularly for genes conferring antibiotic-target protection. Important within the efflux pumps was the Resistance-Nodulation-Division (RND) family, which may have been active in exporting CTAB from cells. Oxidative stress appeared to be the key factor that triggered ARG proliferation by selecting intrinsically resistant species and accentuating the expression of ARG. Our findings suggest that means to mitigate the spread of ARG, such as shown here in a O(2)-based membrane biofilm reactor, need to consider the impacts of stressors, including QAC exposure and stressful operating conditions.202133418325
774280.9935The dissimilarity of antibiotic and quorum sensing inhibitor on activated sludge nitrification system: Microbial communities and antibiotic resistance genes. Effects of antibiotics (azithromycin, AZM, 1-40 mg/L) and quorum sensing inhibitor (QSI, 2(5H)-furanone, 1-40 mg/L) combined pollution with environmental concentration of copper on bacterial/archaeal community and antibiotic resistance genes (ARGs) in activated sludge system were explored. QSI inhibited nitrification more obviously than AZM. AZM and QSI were synergistic inhibitions on bacterial diversity, and AZM inhibited bacterial compositions more than QSI. While, QSI had more impacts on archaeal diversity/compositions. Less interactions among bacteria and archaea communities with Aquimonas as keystone genus. Functional differences in bacteria/archaea communities were little, and AZM had more effects on metabolism. AZM mainly affected nitrifying bacteria (Candidatus Nitrospira nitrificans and Nitrosomonas). Specific denitrifying bacteria were enriched by AZM (Brevundimonas, 1.76-31.69%) and QSI (Comamonas, 0.61-9.61%), respectively. AZM enriched ARGs more easily than QSI and they were antagonistic to proliferation of ARGs. Bacteria were main hosts of ARGs (macrolide-lincosamide-streptogramin B, other/efflux, etc.) and archaea (Methanosphaerula, Methanolobus) carried multiple ARGs.202235306131
804090.9935Removing high strength lincomycin in pharmaceutical wastewater by a bacteria microalgae consortium co-immobilized filter. Lincomycin (LIN) in pharmaceutical wastewater would enter municipal wastewater treatment plants and decrease their performance, leading to residual LIN enter the natural environment and pose serious eco-risk. In this study, a bacterium-microalgae consortium co-immobilized filter (BMCCF) was established and used to remove LIN in artificial pharmaceutical wastewater treatment plants effluents (PWWTPE). LIN removal mechanisms and degradation products' eco-toxicity was studied, and the abundance change of class 1 integrase gene (intI1) and antibiotic resistance genes (ARGs) was monitored. As a result, 98.54% of 82 mg L(-1) LIN was removed within 7 days, LIN removal was mainly attributed to bio-degradation by the Bacillus subtilis strain, and LIN degradation products were less toxic than their substrate. Therefore, the BMCCF established in this study provides a promising alternative for the bio-treatment of pharmaceutical wastewater containing high concentration of LIN.202539490598
8051100.9935Bioelectrochemistry increases the risk of resistance genes proliferation and transfer with sulfamethoxazole pressure decreasing in constructed wetlands: An overlooked double-edged effect. Microbial electrochemical system-enhanced constructed wetland (MES-CW) attracts more attention for antibiotic-contaminated wastewater treatment, but the effect of bioelectrochemistry on resistance genes is still unclear with the removal of antibiotic. In this study, the antibiotic resistance genes (ARGs) dynamics, driving factors and transmission mechanism in effluent and substrate samples were investigated under decreasing sulfamethoxazole (SMX) pressure. Bioelectrochemistry was suitable for reducing the risk of ARGs proliferation and transmission at concentration of 0.1 mg/L SMX. The heterogeneity between effluent and substrate shaped different ARGs occurrence profiles. With SMX concentration decreasing from 10 mg/L to 0.1 mg/L, the ARGs abundance in effluent of MES-CW showed an overall inverted "V" shape (i.e., first up and then down) while that in substrate continued to decrease. Bioelectrochemical microcurrent respectively induced an increase of 61.5 % and 39.3 % in ARGs abundance of effluent and substrate when antibiotic pressure was eliminated. Co-occurrence analysis suggested the rearrangement of ARGs and mobile genetic elements with the decrease of SMX concentrations, which increased the risk of antibiotic resistance transmission. Metagenomic binning disclosed that pathogenic bacteria were enriched in MES-CW and ARGs hosts showed multiple resistance after SMX pressure elimination. Improving voltage to alleviate the proliferation of antibiotic resistant bacteria and resistance genes was preliminarily attempted. This study unveils the double-edged effects of bioelectrochemistry on ARGs proliferation and transfer in CW with the decrease of antibiotic concentration for the first time, and broadens the knowledge of ARGs evolution in MES-CW. These findings provide a guidance for the safe operation of MES-CW for rural livestock wastewater treatment.202540816173
8065110.9934Synergistic enhancement effect of straw-earthworms in the reduction of sulfamethoxazole and antibiotic resistance genes. Soil antibiotic pollution is a global concern. It has been confirmed that straw or earthworm can enhance microbial degradation of antibiotics in soil. However, in the C/N transformation processes of soil ecosystems, straw and earthworms are closely interconnected. Whether their interaction can further enhance microbial degradation of antibiotic pollution and the underlying mechanisms remain to be explored. This study conducted a 90 days co-incubation experiment with four treatments: straw + earthworms + sulfamethoxazole (RS-EW-SMX), straw + SMX (RS-SMX), earthworms + SMX (EW-SMX), and SMX alone (SMX). Residual SMX, its degradation intermediates, and microbial communities were monitored at multiple timepoints. Results indicated an exponential decline in SMX degradation rates across treatments. By day 90, SMX was nearly completely degraded in all treatment groups. However, the combined effect of straw and earthworms significantly enhanced the degradation efficiency of SMX. During the rapid degradation phase, SMX in above four treatments decreased from 20.0 mg kg(-1) to 0.93, 1.88, 5.26 and 7.02 mg kg(-1), respectively at day 10. Furthermore, the RS-EW-SMX treatment promoted SMX transformation into low-molecular-weight intermediates and increased the relative abundance of SMX-degrading bacteria by 1.35, 2.01, and 2.17-fold compared to RS-SMX, EW-SMX, and SMX, respectively. SMX degradation efficiency exhibited a strong positive linear correlation with the relative abundance of degrading bacteria across all treatments (R(2) = 0.961). Concurrently, analysis revealed that straw presence facilitated the targeted enrichment of SMX-degrading bacteria within the earthworm gut, concomitant with a reduction in associated antibiotic resistance genes (ARGs). This synergistic interaction between straw and earthworms, mediated through the gut microbiome and carbon utilization, constitutes a primary mechanism underpinning the accelerated SMX degradation observed. These findings reveal a novel macrofauna-plant residues interaction mechanism for improved in situ antibiotic bioremediation, providing practical solutions for soil pollution mitigation.202540914087
8067120.9934Enhanced control of sulfonamide resistance genes and host bacteria during thermophilic aerobic composting of cow manure. Traditional composting has already shown a certain effect in eliminating antibiotic residues, antibiotic-resistant bacteria (ARBs), and antibiotic resistance genes (ARGs). It is worth noting that the rebounding of ARGs and the succession of the bacterial community during conventional aerobic composting are still serious threats. Considering the probable risk, improved and adaptable technologies are urgently needed to control antibiotic resistance efficiently. This study monitored how thermophilic aerobic composting affected the ARGs, as well as the bacterial diversity during the composting of cow manure spiked with sulfamethoxazole (SMX) at different concentrations. Results showed that the degradation of SMX was enhanced during thermophilic aerobic composting (control > SMX25 > SMX50 > SMX100) and was no longer detected after 20 days of composting. High temperature or heat significantly stimulated the rebounding of certain genes. After 35 days, the abundance of detected genes (sul2, sulA, dfrA7, and dfrA1) significantly decreased (p < 0.05) in control and antibiotic-spiked treatments, except for sul1. The addition of three concentrations of SMX elicited a sharp effect on bacterial diversity, and microbial structure in SMX25 led to significant differences with others (p < 0.05). The network analysis revealed more rigorous interactions among ARGs and abundant genera, suggesting that the host of ARGs potentially increased at low concentrations of SMX. Especially, genera g_norank_f__Beggiatoaceae, Ruminiclostridium, Caldicoprobacter, g_norank_o_MBA03, Hydrogenispora, and Ruminiclostridium_1 were major potential hosts for sul1. In conclusion, the rebounding of ARGs could be intermitted partially, and more efficient control of antibiotic resistance could be achieved in the thermophilic composting compared to conventional methods.202133582626
7909130.9934Simultaneous efficient removal of tetracycline and mitigation of antibiotic resistance genes enrichment by a modified activated sludge process with static magnetic field. To address the increasing issue of antibiotic wastewater, this study applied a static magnetic field (SMF) to the activated sludge process to increase the efficiency of tetracycline (TC) removal from swine wastewater and to reveal its enhanced mechanisms. The results demonstrated that the SMF-modified activated sludge process could achieve almost complete TC removal at sludge loading rates of 0.3 mg TC/g MLSS/d. Analysis of zeta potential and extracellular polymeric substances composition of the activated sludge revealed that SMF increased electrostatic interactions between TC and activated sludge and made activated sludge has much more binding sites, finally resulting in the increased TC biosorption. Metagenomic analysis showed that SMF promoted the enrichment of ammonia-oxidizing bacteria, TC-degrading bacteria, and aromatic compounds-degrading bacteria; it also enhanced ammonia monooxygenase- and cytochrome P450-mediated TC metabolism while upregulating functional genes associated with oxidase, reductase, and dehydrogenase - all contributing to increased TC biodegradation. Additionally, SMF mitigated the enrichment and spread of antibiotic resistance genes (ARGs) by decreasing the abundance of potential hosts of ARGs and inhibiting the upregulation of genes encoding ABC transporters and putative transposase. Based on these findings, this study demonstrates that magnetic field is an enhancement strategy with great potential to relieve the harmful impacts of the growing antibiotic wastewater problem on human health and the ecosystem.202439038424
7912140.9934Distinct 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
7543150.9934Aerobic 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
7914160.9933Response of partial nitrification sludge to the single and combined stress of CuO nanoparticles and sulfamethoxazole antibiotic on microbial activity, community and resistance genes. Considering the inevitable release of antibiotics and nanoparticles (NPs) into the nitrogen containing wastewater, the combined impact of CuO NPs and sulfamethoxazole (SMX) antibiotic on partial nitrification (PN) process was investigated in four identical reactors. Results showed that the bioactivity of the aerobic ammonia-oxidizing bacteria (AOB) decreased by half after they were exposed to the combination of CuO NPs and SMX for short-term; however, there was no obvious variation in the bioactivity of AOB when they were exposed to either CuO NPs or SMX. During long-term exposure, the ammonia removal efficiency (ARE) of CuO NPs improved whereas that of SMX decreased, while the combination of CuO NPs and SMX significantly decreased ARE from 62.9% (in control) to 38.2% and had an unsatisfactory self-recovery performance. The combination of CuO NPs and SMX significantly changed the composition of microbial community, decreased the abundance of AOB, and significantly suppressed PN process. Reegarding the resistance genes, the CuO NPs-SMX combination did not improve the expression of copA, cusA, sul1 and sul2; however, it significantly induced the expression of sul3 and sulA.202032050397
7910170.9933Tetracycline degradation by a mixed culture of halotolerant fungi-bacteria under static magnetic field: Mechanism and antibiotic resistance genes transfer. Efficient antibiotics removal lowers the transmission risk of antibiotic resistance genes (ARGs). However, low efficiency limits the application of biological methods for antibiotics removal. Herein, a mixed culture of halotolerant fungi-bacteria was used for treatment of saline wastewater containing tetracycline (TC). Furthermore, static magnetic field (SMF) was used to increase TC removal. The study examined the effectiveness of SMF in removing antibiotics from saline wastewater and the associated risk of ARGs transmission. The results demonstrated that the application of a 40 mT SMF significantly improved the TC removal efficiency by 37.09 %, compared to the control (SMF=0) The TC was mainly removed through biodegradation and adsorption. In biodegradation, SMF enhanced electron transport system activity, and activities of lignin-degrading enzymes which led to higher TC biodegradation. The activity of lactate dehydrogenase and malondialdehyde decreased, lowering the damage of microbial cell membranes by TC. During the adsorption process, higher generation of extracellular polymeric substances was observed under SMF, which caused an increase in TC removal via adsorption. Microbial community analysis revealed that SMF facilitated the enrichment of TC-degrading microorganisms. Under SMF, vertical gene transfer of ARGs increased, while horizontal gene transfer risk decreased due to a reduction in mobile genetic elements (intl1) abundance. This study demonstrates that SMF is a promising strategy for enhancing TC removal efficiency, providing a basis for improved antibiotic wastewater management.202540199074
7937180.9933Effects 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
7897190.9933Enhanced 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