# | Rank | Similarity | Title + Abs. | Year | PMID |
|---|---|---|---|---|---|
| 0 | 1 | 2 | 3 | 4 | 5 |
| 8050 | 0 | 1.0000 | Effects of antibiotics on corncob supported solid-phase denitrification: Denitrification and antibiotics removal performance, mechanism, and antibiotic resistance genes. Solid-phase denitrification (SPD) has been used in wastewater treatment plant effluent to enhance nitrate removal, and antibiotics co-existing in the effluent is a common environmental problem. In this study, it was systematically investigated the effect of single trace sulfamethoxazole (SMX)/trimethoprim (TMP) and their mixture on microbial denitrification performance, the antibiotics removal, and antibiotics resistance genes (ARGs) in corncob supported SPD system. The average denitrification rate was improved by 46.90% or 61.09% with single 50 µg/L SMX or TMP, while there was no significant inhibition with mixed SMX and TMP. The abundance of dominant denitrifiers (Comamonadaceae family and Azospia) and fermentation bacteria (Ancalomicrobium) were consistent with the denitrification performance of different antibiotics groups. Single SMX and TMP achieved relatively higher denitrification gene and enzyme abundance. Mixed SMX and TMP improved the denitrification gene copies, but they reduced the key denitrification enzymes except for EC 1.7.7.2. Additionally, the removal efficiency of TMP (56.70% ± 3.18%) was higher than that of SMX (25.44% ± 2.62%) in single antibiotic group, and the existence of other antibiotics (i.e. SMX or TMP) had no significant impact on the TMP or SMX removal performance. Biodegradation was the main removal mechanism of SMX and TMP, while sludge and corncob adsorption contributed a little to their removal. SMX had the risk of sulfanilamide resistance genes (SRGs) dissemination. Furthermore, network analysis indicated that Niveibacterium and Bradyrhizobium were the potential hosts of SRGs, which promoted the horizontal transmission of ARGs. | 2023 | 37032040 |
| 8044 | 1 | 0.9996 | Effect of tetracycline on nitrogen removal in Moving Bed Biofilm Reactor (MBBR) System. The effect of tetracycline (TC) on nitrogen removal in wastewater treatment plants has become a new problem. This study investigated the effects of TC on nitrogen removal using a Moving Bed Biofilm Reactor system. The results showed that there was no significant effect on nitrogen removal performance when the concentration of TC was 5 mg/L, and that the total nitrogen (TN) removal efficiency could reach 75-77%. However, when the concentration of TC increased to 10 mg/L, the denitrification performance was affected and the TN removal efficiency decreased to 58%. The abundance of denitrifying bacteria such as those in the genus Thauera decreased, and TC-resistant bacteria gradually became dominant. At a TC concentration of 10 mg/L, there were also increases and decreases, respectively, in the abundance of resistance and denitrification functional genes. The inhibitory effect of TC on denitrification was achieved mainly by the inhibition of nitrite-reducing bacteria. | 2022 | 35007308 |
| 8041 | 2 | 0.9996 | Insights into the microalgae-bacteria consortia treating swine wastewater: Symbiotic mechanism and resistance genes analysis. This study investigated the effects of microalgae-bacteria consortia (MBC) (Chlorella pyrenoidosa-activated sludge (AS)) treating swine wastewater with low C/N ratios. After co-culture, the removal rates of NH(4)(+)-N and PO(4)(3-)-P increased by 53.84% and 43.52%. Furthermore, the sulfamethoxazole (SMX) degradation rates in MBC were slightly higher than in the activated sludge process. Interestingly, the absolute abundance of antibiotic resistance genes (ARGs) in effluent from MBC is relatively less than in the AS process. C. pyrenoidosa has a negative zeta potential that allows bacteria to adhere to its surface. The concentrations of carbohydrates and proteins in extracellular polymeric substance (EPS) of MBC dramatically increased compared with the AS process. At the phylum level, Proteobacteria, Bacteroidota, and Cyanobacteria were the main bacteria, while Ascomycota and Basidiomycota were the primary fungi in MBC. Overall, those findings lead to a better understanding of the swine wastewater containing antibiotic treatment by MBC. | 2022 | 35217162 |
| 8042 | 3 | 0.9996 | Algal-bacterial consortium mediated system offers effective removal of nitrogen nutrients and antibiotic resistance genes. The sulfonamide antibiotic resistance genes (ARGs) especially sul1 was identified as the dominant in eutrophic water. The performance of Chlorella vulgaris-B. licheniformis consortium toward sul1 removal, total nitrogen (TN) removal, and the mechanism of sul1 removal was investigated. The removal efficiency of exogenous ARGs plasmids carrying sul1 reached (97.2 ± 2.3)%. The TN removal rate reached (98.5 ± 1.2)%. The enhancements of carbon metabolism, nitrogen metabolism, aminoacyl-tRNA biosynthesis, and glycoproteins had significant influences on sul1 and TN removals, under the premise of normal growth of algae and bacteria. The quantitative polymerase chain reaction (qPCR) results suggested that the absolute abundances of sul1 were low in algal-bacterial systems (0 gene copies/mL) compared with individual systems ((1 × 10(6) ± 15) gene copies/mL). The duplication of sul1 was inhibited in algal cells and bacterial cells. The algal-bacterial consortium seems to be a promising technology for wastewater treatment with a potential to overcome the eutrophication and ARGs challenges. | 2022 | 36049708 |
| 8048 | 4 | 0.9995 | Ecological risks of sulfonamides and quinolones degradation intermediates: Toxicity, microbial community, and antibiotic resistance genes. The ecological risks posed by incompletely degraded antibiotic intermediates in aquatic environments warrant significant attention. This study investigated the degradation mechanisms of sulfonamides (sulfadiazine, sulfamethoxazole) and quinolones (ciprofloxacin, norfloxacin) during thermally activated persulfate (TAP) treatment. The main degradation mechanisms for sulfonamides involved S-N bond cleavage and -NH(2) oxidation mediated by sulfate and hydroxyl radicals, whereas quinolone degradation occurred primarily through piperazine ring cleavage facilitated by a single linear oxygen. Toxic degradation intermediates were found to be enriched with bacteria in real water samples, including Aeromonas (SDZ-50, 9.61%), Acinetobacter (SMZ-50, 21.91%), unclassified Archaea (CIP-50, 19.32%), and Herbaspirillum (NOR-50, 17.36%). Meanwhile, the abundance of sulfonamide-associated antibiotic resistance genes (ARGs) (sul1 and sul2) and quinolone-associated ARGs (mfpA, emrA, and lfrA) significantly increased, with SMZ-50 and NOR-50 reaching 659.34 and 2009.98 RPKM, respectively. Correlation analysis revealed differences in host diversity and composition driven by the same classes of antibiotics and their intermediates. | 2025 | 39662843 |
| 8046 | 5 | 0.9995 | Responses of aerobic granular sludge to fluoroquinolones: Microbial community variations, and antibiotic resistance genes. In this study, aerobic granular sludge (AGS) was operated under high levels of ammonium for removing three fluoroquinolones (FQs), i.e., ciprofloxacin (CFX), ofloxacin (OFX), and norfloxacin (NFX) at 3, 300, and 900 µg/L, respectively. Two key objectives were to investigate the differential distribution of antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) in sludge fractions and to evaluate correlations between ARGs and MGEs to nitrifying and denitrifying bacteria. AGS showed excellent stability under the exposure of FQs, with nitrite-oxidizing bacteria (NOB) more sensitive to FQs than ammonium-oxidizing bacteria (AOB). Specific oxygen utilization rates (SOUR) showed a reduction of 26.9% for NOB but only 4.0% of the reduced activity of AOB by 3 μg/L FQs. AGS performed better removal efficiencies for CFX and NFX than OFX, and the efficiencies increased with their elevated concentrations, except at 900 μg/L FQs. The elevated FQ concentrations led to a significant enrichment of intI1 and genus Thauera, while qnrD and qnrS showed no accumulation. Compared to nitrifiers, FQs relevant ARGs and the intI1 gene preferred to exist in denitrifiers, and the abundance of denitrifiers behaved a decreasing trend with the sludge size. Two quinoline-degrading bacteria were found in the AGS system, i.e., Alicycliphilus and Brevundimonas, possibly carrying qnrS and qnrD, respectively. Their relative abundance increased with the sludge size, which was 2.18% in sludge <0.5 mm and increased to 3.70% in sludge >2.0 mm, suggesting that the AGS may be a good choice in treating FQs-containing wastewater. | 2021 | 33676249 |
| 8006 | 6 | 0.9995 | Removal of antibiotic resistant bacteria and antibiotic resistance genes in wastewater effluent by UV-activated persulfate. The emerging antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) are increasingly appreciated to be as important as microbial contaminants. This paper focused on UV-activated persulfate (UV/PS), an advanced oxidation process, in removing ARB and ARGs from secondary wastewater effluent. Results showed that the inactivation efficiency of macrolides-resistant bacteria (MRB), sulfonamides-resistant bacteria (SRB), tetracyclines-resistant bacteria (TRB) and quinolones-resistant bacteria (QRB) by UV/PS reached 96.6 %, 94.7 %, 98.0 % and 99.9 % in 10 min, respectively. UV/PS also showed significant removal efficiency on ARGs. The reduction of total ARGs reached 3.84 orders of magnitude in UV/PS which is more than that in UV by 0.56 log. Particularly, the removal of mobile genetic elements (MGE) which might favor the horizontal gene transfer of ARGs among different microbial achieved 76.09 % by UV/PS. High-throughput sequencing revealed that UV/PS changed the microbial community. The proportions of Proteobacteria and Actinobacteria that pose human health risks were 4.25 % and 1.6 % less than UV, respectively. Co-occurrence analyzes indicated that ARGs were differentially contributed by bacterial taxa. In UV/PS system, hydroxyl radical and sulfate radical contributed to the removal of bacteria and ARGs. Our study provided a new method of UV/PS to remove ARGs and ARB for wastewater treatment. | 2020 | 31954307 |
| 8065 | 7 | 0.9995 | Synergistic 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. | 2025 | 40914087 |
| 8018 | 8 | 0.9995 | Analysis for microbial denitrification and antibiotic resistance during anaerobic digestion of cattle manure containing antibiotic. This study investigated the effects of tylosin (0, 10, and 100 mg/kg dry weight) on the denitrification genes and microbial community during the anaerobic digestion of cattle manure. N(2) emissions were reduced and N(2)O emissions were increased by 10 mg/kg tylosin. Adding 100 mg/kg tylosin increased the emission of both N(2)O and N(2). The different responses of denitrifying bacteria and genes to tylosin may have been due to the presence of antibiotic resistance genes (ARGs). Network analysis indicated that denitrification genes and ARGs had the same potential host bacteria. intI1 was more important for the horizontal transfer of denitrification genes and ARGs during anaerobic digestion than intI2. The anaerobic digestion of manure containing tylosin may increase nitrogen losses and the associated ecological risk. | 2019 | 31326686 |
| 8038 | 9 | 0.9995 | Hydroxyl radicals dominated the reduction of antibiotic resistance genes by inactivating Gram-negative bacteria during soil electrokinetic treatment. Antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) are emerging contaminants that widely exist in the environment. Effective reduction of ARB and ARGs from soil and water could be achieved by electrokinetic remediation (EKR) technology. In water, hydroxyl radicals (·OH) are proved to play a major role in the EKR process; while the reduction mechanism of ARB and ARGs is still unclear in soil. In this study, different concentrations of hydroxyl radical scavengers (salicylic acid) were added to the EKR system to explore the possible role of ·OH in the reduction of ARB and ARGs. The results showed that generally, ·OH played a more vital role in the reduction of ARB (65.24-72.46%) compared to the reduction of total cultivable bacteria (57.50%). And ·OH contributed to a higher reduction of sul genes (60.94%) compared to tet genes (47.71%) and integrons (36.02%). It was found that the abundance of Gram-negative bacteria (Chloroflexi, Acidobacteria and norank_c_Acidobacteria) was significantly reduced, and the correlation between norank_f_Gemmatimonadaceae and sul1 was weakened in the presence of ·OH. Correlation analysis indicated that the abundance of ARGs (especially sul1) was closely related to the Gram-negative bacteria (Proteobacteria, Acidobacteria, and Gemmatimonadetes) in the soil EKR treatment. Moreover, changes in bacterial community structure affected the abundance of ARB and ARGs indirectly. Overall, this study revealed the reduction mechanism of ARB and ARGs by ·OH in the soil EKR system for the first time. These findings provide valuable support for soil remediation efforts focusing on controlling antibiotic resistance. | 2024 | 39312876 |
| 8043 | 10 | 0.9995 | Effect of tetracycline on bio-electrochemically assisted anaerobic methanogenic systems: Process performance, microbial community structure, and functional genes. Bio-electrochemically assisted anaerobic methanogenic systems (An-BES) are highly effective in wastewater treatment for methane production and degradation of toxic compounds. However, information on the treatment of antibiotic-bearing wastewater in An-BES is still very limited. This study therefore investigated the effect of tetracycline (TC) on the performance, microbial community, as well as functional and antibiotic resistance genes of An-BES. TC at 1 and 5 mg/L inhibited methane production by less than 4.8% compared to the TC-free control. At 10 mg/L TC, application of 0.5 and 1.0 V decreased methane production by 14 and 9.6%, respectively. Under the effect of 1-10 mg/L TC, application of 1.0 V resulted in a decrease of current from 42.3 to 2.8 mA. TC was mainly removed by adsorption; its removal extent increased by 19.5 and 32.9% with application of 0.5 and 1.0 V, respectively. At 1.0 V, current output was not recovered with the addition of granular activated carbon, which completely removed TC by adsorption. Metagenomic analysis showed that propionate oxidizing bacteria and methanogens were more abundant in electrode biofilms than in suspended culture. Antibiotic resistance genes (ARGs) were less abundant in biofilms than in suspended culture, regardless of whether voltage was applied or not. Application of 1.0 V resulted in the enrichment of Geobacter in the anode and Methanobacterium in the cathode. TC inhibited exoelectrogens, propionate oxidizing bacteria, and the methylmalonyl CoA pathway, leading to a decrease of current output, COD consumption, and methane production. These findings deepen our understanding of the inhibitory effect of TC in An-BES towards efficient bioenergy recovery from antibiotic-bearing wastewater, as well as the response of functional microorganisms to TC in such systems. | 2022 | 35533856 |
| 7543 | 11 | 0.9995 | Aerobic 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. | 2024 | 39153702 |
| 8055 | 12 | 0.9995 | Effects of nano-zerovalent iron on antibiotic resistance genes during the anaerobic digestion of cattle manure. This study investigated the effects of adding nano-zerovalent iron (nZVI) at three concentrations (0, 80, and 160 mg/L) on the methane yield and the fate of antibiotic resistance genes (ARGs) during the anaerobic digestion (AD) of cattle manure. The addition of nZVI effectively enhanced the methane yield, where it significantly increased by 6.56% with 80 mg/L nZVI and by 6.43% with 160 mg/L nZVI. The reductions in the abundances of ARGs and Tn916/1545 were accelerated by adding 160 mg/L nZVI after AD. Microbial community analysis showed that nZVI mainly increased the abundances of bacteria with roles in hydrolysis and acidogenesis, whereas it reduced the abundance of Acinetobacter. Redundancy analysis indicated that the changes in mobile genetic elements made the greatest contribution to the fate of ARGs. The results suggest that 160 mg/L nZVI is a suitable additive for reducing the risks due to ARGs in AD. | 2019 | 31247529 |
| 8053 | 13 | 0.9995 | Increasing the removal efficiency of antibiotic resistance through anaerobic digestion with free nitrous acid pretreatment. Swine manure is a significant reservoir for antibiotic resistance. Anaerobic digestion (AD) is a common biological process used to treat swine manure but still faces low efficiencies in biogas production and antibiotic resistance removal. It is here shown that AD with free nitrous acid pretreatment (FNA) was effective in reducing antibiotic resistance genes (ARGs) in swine manure. FNA pretreatment (nitrite =250 mg N/L, pH=5.0, temperature=20 ± 1 °C) simultaneously reduced antibiotics (Tetracyclines, Quinones and Sulfonamides), inactivated antibiotics resistance bacteria (ARB) by 0.5-3 logs, and decreased ARGs tet, sul and qnr by 1-2, 1-3 and 0.5 logs, respectively. In the following AD step, the total residual ARGs was reduced to ~3.49 × 10(7) gene copies/g dry total solids (TS), ~1 log lower than that in the AD without pretreatment (3.55 ×10(8) gene copies/g dry TS). Microbial community and network analyses revealed that the ARG removal was mainly driven by the direct FNA effect on reducing ARGs and antibiotics, not related to ARB. Besides, the FNA pretreatment doubled biochemical methane production potential from swine manure. Together these results demonstrate that AD with FNA pretreatment is a useful process greatly facilitating swine manure management. | 2022 | 35816802 |
| 8054 | 14 | 0.9995 | Effects of nanoscale zero-valent iron on the performance and the fate of antibiotic resistance genes during thermophilic and mesophilic anaerobic digestion of food waste. The effects of nanoscale zero-valent iron (nZVI) on the performance of food waste anaerobic digestion and the fate of antibiotic resistance genes (ARGs) were investigated in thermophilic (TR) and mesophilic (MR) reactors. Results showed that nZVI enhanced biogas production and facilitated ARGs reduction. The maximum CH(4) production was 212.00 ± 4.77 ml/gVS with 5 g/L of nZVI in MR. The highest ARGs removal ratio was 86.64 ± 0.72% obtained in TR at nZVI of 2 g/L. nZVI corrosion products and their contribution on AD performance were analyzed. The abundance of tetracycline genes reduced significantly in nZVI amended digesters. Firmicutes, Chloroflexi, Proteobacteria and Spirochaetes showed significant positive correlations with various ARGs (p < 0.05) in MR and TR. Redundancy analysis indicated that microbial community was the main factor that influenced the fate of ARGs. nZVI changed microbial communities, with decreasing the abundance bacteria belonging to Firmicutes and resulting in the reduction of ARGs. | 2019 | 31505392 |
| 8057 | 15 | 0.9995 | SiO(2) nanoparticles can enhance nitrogen retention and reduce copper resistance genes during aerobic composting of swine manure. SiO(2) nanoparticles (SiO(2) NPs) are low-cost, environmentally friendly materials with significant potential to remove pollutants from complex environments. In this study, SiO(2) NPs were used for the first time as an additive in aerobic composting to enhance nitrogen retention and reduce the expression of copper resistance genes. The addition of 0.5 g kg(-1) SiO(2) NPs effectively reduced nitrogen loss by 72.33 % by decreasing denitrification genes (nosZ, nirK, and napA) and increasing nitrogen fixation gene (nifH). The dominant factors affecting nitrification and denitrification genes were Firmicutes and C/N ratio. Additionally, SiO(2) NPs decreased copper resistance genes by 28.96 % - 37.52 % in compost products. Copper resistance genes decreased most in the treatment with 0.5 g kg(-1) SiO(2) NPs. In summary, 0.5 g kg(-1) SiO(2) NPs have the potential to reduce copper resistance genes and enhance nitrogen retention during aerobic composting, which may be used to improve compost quality. | 2024 | 39374833 |
| 8092 | 16 | 0.9995 | Effect of pH on the mitigation of extracellular/intracellular antibiotic resistance genes and antibiotic resistance pathogenic bacteria during anaerobic fermentation of swine manure. Effects of various initial pH values (i.e., 3, 5, 7, 11) during anaerobic fermentation of swine manure on intracellular and extracellular antibiotic resistance genes (iARGs and eARGs) and ARG-carrying potential microbial hosts were investigated. The abundance of almost all iARGs and eARGs decreased by 0.1-1.7 logs at pH 3 and pH 5. The abundance of only three iARGs and eARGs decreased by 0.1-0.9 logs at pH 7 and pH 11. Under acidic initial fermentation conditions (pH 3 and pH 5), the ARG removal effect was more pronounced. Acidic conditions (pH 3 and pH 5) significantly reduced the diversity and abundance of the microbial community, thereby eliminating many potential ARG hosts and antibiotic-resistant pathogenic bacteria (ARPB). Therefore, the study results contribute to the investigation of the effects of swine manure anaerobic fermentation on the removal and risk of contamination of ARGs and ARPB. | 2023 | 36746211 |
| 8004 | 17 | 0.9995 | Elimination of antibiotic-resistant bacteria and resistance genes by earthworms during vermifiltration treatment of excess sludge. Vermifiltration (VF) and a conventional biofilter (BF, no earthworm) were investigated by metagenomics to evaluate the removal rates of antibiotic-resistant bacteria (ARB), antibiotic resistance genes (ARGs), and class 1 integron-integrase (intI1), as well as the impact mechanism in combination with the microbial community. According to the findings of qPCR and metagenomics, the VF facilitated greater removal rates of ARGs (78.83% ± 17.37%) and ARB (48.23% ± 2.69%) than the BF (56.33% ± 14.93%, 20.21% ± 6.27%). Compared to the control, the higher biological activity of the VF induced an increase of over 60% in the inhibitory effect of earthworm coelomic fluid on ARB. The removal rates of ARGs by earthworm guts also reached over 22%. In addition, earthworms enhanced the decomposition of refractory organics, toxic, and harmful organics, which led to a lower selective pressure on ARGs and ARB. It provides a strategy for reducing resistant pollution in sewage treatment plants and recognizing the harmless stability of sludge. | 2024 | 38170354 |
| 8064 | 18 | 0.9995 | Removal of sulfamethoxazole and antibiotic resistance genes in paddy soil by earthworms (Pheretima guillelmi): Intestinal detoxification and stimulation of indigenous soil bacteria. Vermiremediation, which use earthworms to remove contaminants from soil, has been proven to be an alternative, low-cost technology. However, the effects of earthworm activity, especially the degraders in earthworm intestines, on the fate of sulfamethoxazole (SMX), and the effects of intestinal bacteria on degrading bacteria in soil are unclear. In this study, the effects of earthworms on the fate of SMX and related antibiotic resistance genes (ARGs) were investigated. Special attention was paid to the impact of earthworms on SMX degradation efficiency, degradation products, related ARGs, and degraders in both soil and earthworm intestines; the effect of intestinal bacteria on soil bacteria associated with SMX was also studied. Earthworms significantly accelerated SMX degradation by both intestinal detoxification and the stimulation of indigenous soil bacteria. Compared with the treatment without earthworms, the treatment with earthworms reduced SMX residues by 25.1 %, 49.2 %, 35.7 %, 34.2 %, and 35.7 % on the 10th, 20th, 30th, 60th, and 90th days, respectively. Compared with those in soil (treated with earthworms), the SMX residues in wormcasts were further reduced by 12.2-29.0 % from the 2nd to the 20th day, producing some unique anaerobic degradation products that were distinct from those in the soil. In earthworm intestines, SMX degradation was enhanced by bacteria of the genera Microvirga, Sphingomonas, Methylobacterium, Bacillus, and Tumebacillus. All of these bacteria (except Bacillus spp.) entered and colonised the soil with wormcasts, further promoting SMX degradation. Additionally, earthworms removed a significant number of ARGs by increasing the fraction of potential SMX degraders and inhibiting the potential hosts of ARGs and int1. This study demonstrated that earthworms could remediate SMX-contaminated soil by enhancing the removal of SMX and ARGs. | 2022 | 35985593 |
| 7192 | 19 | 0.9995 | Sulfamethoxazole and COD increase abundance of sulfonamide resistance genes and change bacterial community structures within sequencing batch reactors. The abundant microbial community in biological treatment processes in wastewater treatment plants (WWTPs) may potentially enhance the horizontal gene transfer of antibiotic resistance genes with the presence of antibiotics. A lab-scale sequencing batch reactor was designed to investigate response of sulfonamide resistance genes (sulI, sulII) and bacterial communities to various concentrations of sulfamethoxazole (SMX) and chemical oxygen demand (COD) of wastewater. The SMX concentrations (0.001 mg/L, 0.1 mg/L and 10 mg/L) decreased with treatment time and higher SMX level was more difficult to remove. The presence of SMX also significantly reduced the removal efficiency of ammonia nitrogen, affecting the normal function of WWTPs. All three concentrations of SMX raised both sulI and sulII genes with higher concentrations exhibiting greater increases. The abundance of sul genes was positive correlated with treatment time and followed the second-order reaction kinetic model. Interestingly, these two genes have rather similar activity. SulI and sulII gene abundance also performed similar response to COD. Simpson index and Shannon-Weiner index did not show changes in the microbial community diversity. However, the 16S rRNA gene cloning and sequencing results showed the bacterial community structures varied during different stages. The results demonstrated that influent antibiotics into WWTPs may facilitate selection of ARGs and affect the wastewater conventional treatment as well as the bacteria community structures. | 2017 | 28211331 |