# | Rank | Similarity | Title + Abs. | Year | PMID |
|---|---|---|---|---|---|
| 0 | 1 | 2 | 3 | 4 | 5 |
| 8109 | 0 | 0.9949 | The fate of antibiotic resistance genes and their influential factors in swine manure composting with sepiolite as additive. Manures are storages for antibiotic resistance genes (ARGs) entering the environment. This study investigated the effects of adding sepiolite at 0%, 2.5%, 5%, and 7.5% (CK, T1, T2, and T3, respectively) on the fates of ARGs during composting. The relative abundances (RAs) of the total ARGs in CK and T3 decreased by 0.23 and 0.46 logs, respectively, after composting. The RAs of 10/11 ARGs decreased in CK, whereas they all decreased in T3. The reduction in the RA of the total mobile genetic elements (MGEs) was 1.26 times higher in T3 compared with CK after composting. The bacterial community accounted for 47.93% of the variation in the abundances of ARGs. Network analysis indicated that ARGs and MGEs shared potential host bacteria (PHB), and T3 controlled the transmission of ARGs by reducing the abundances of PHB. Composting with 7.5% sepiolite is an effective strategy for reducing the risk of ARGs proliferating. | 2022 | 35063626 |
| 8108 | 1 | 0.9947 | Insights into the beneficial effects of woody peat for reducing abundances of antibiotic resistance genes during composting. Antibiotic resistance genes (ARGs) in manure endangered human health, while heavy metals in manure will pose selective pressure on ARGs. This study explored the effects on ARGs of adding woody peat during composting at different ratios (0 (CK), 5% (T1), and 15% (T2)). After composting, the relative abundances of 8/11 ARGs were 6.97-38.09% and 10.73-54.31% lower in T1 and T2, respectively, than CK. The bioavailable Cu content was 1.40% and 18.40% lower in T1 and T2, respectively, than CK. Network analysis showed that ARGs, mobile genetic elements (MGEs), and metal resistance genes possessed common potential host bacteria, such as Streptococcus, Dietzia, and Corynebacterium_1. Environmental factors, especially bioavailable Cu, and MGEs accounted for 80.75% of the changes in the abundances of ARGs. In conclusion, 15% Woody peat is beneficial to decrease the bioavailable Cu content and weaken horizontal gene transfer for controlling the spread of ARGs during composting. | 2021 | 34534940 |
| 7757 | 2 | 0.9947 | Removal of antibiotics and antibiotic resistance genes from domestic sewage by constructed wetlands: Effect of flow configuration and plant species. This study aims to investigate the removal of antibiotics and antibiotic resistance genes (ARGs) in raw domestic wastewater by various mesocosm-scale constructed wetlands (CWs) with different flow configurations or plant species including the constructed wetland with or without plant. Six mesocosm-scale CWs with three flow types (surface flow, horizontal subsurface flow and vertical subsurface flow) and two plant species (Thaliadealbata Fraser and Iris tectorum Maxim) were set up in the outdoor. 8 antibiotics including erythromycin-H2O (ETM-H2O), monensin (MON), clarithromycin (CTM), leucomycin (LCM), sulfamethoxazole (SMX), trimethoprim (TMP), sulfamethazine (SMZ) and sulfapyridine (SPD) and 12 genes including three sulfonamide resistance genes (sul1, sul2 and sul3), four tetracycline resistance genes (tetG, tetM, tetO and tetX), two macrolide resistance genes (ermB and ermC), two chloramphenicol resistance genes (cmlA and floR) and 16S rRNA (bacteria) were determined in different matrices (water, particle, substrate and plant phases) from the mesocosm-scale systems. The aqueous removal efficiencies of total antibiotics ranged from 75.8 to 98.6%, while those of total ARGs varied between 63.9 and 84.0% by the mesocosm-scale CWs. The presence of plants was beneficial to the removal of pollutants, and the subsurface flow CWs had higher pollutant removal than the surface flow CWs, especially for antibiotics. According to the mass balance analysis, the masses of all detected antibiotics during the operation period were 247,000, 4920-10,600, 0.05-0.41 and 3500-60,000μg in influent, substrate, plant and effluent of the mesocosm-scale CWs. In the CWs, biodegradation, substrate adsorption and plant uptake all played certain roles in reducing the loadings of nutrients, antibiotics and ARGs, but biodegradation was the most important process in the removal of these pollutants. | 2016 | 27443461 |
| 8054 | 3 | 0.9947 | 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 |
| 7998 | 4 | 0.9947 | Seasonal variation and removal efficiency of antibiotic resistance genes during wastewater treatment of swine farms. The seasonal variation and removal efficiency of antibiotic resistance genes (ARGs), including tetracycline resistance genes (tetG, tetM, and tetX) and macrolide (ermB, ermF, ereA, and mefA), were investigated in two typical swine wastewater treatment systems in both winter and summer. ARGs, class 1 integron gene, and 16S rRNA gene were quantified using real-time polymerase chain reaction assays. There was a 0.31-3.52 log variation in ARGs in raw swine wastewater, and the abundance of ARGs in winter was higher than in summer. tetM, tetX, ermB, ermF, and mefA were highly abundant. The abundance of ARGs was effectively reduced by most individual treatment process and the removal efficiencies of ARGs were higher in winter than in summer. However, when examining relative abundance, the fate of ARGs was quite variable. Anaerobic digestion reduced the relative abundance of tetX, ermB, ermF, and mefA, while lagoon treatment decreased tetM, ermB, ermF, and mefA. Sequencing batch reactor (SBR) decreased tetM, ermB, and ermF, but biofilters and wetlands did not display consistent removal efficiency on ARGs in two sampling seasons. As far as the entire treatment system is concerned, ermB and mefA were effectively reduced in both winter and summer in both total and relative abundance. The relative abundances of tetG and ereA were significantly correlated with intI1 (p < 0.01), and both tetG and ereA increased after wastewater treatment. This may pose a great threat to public health. | 2017 | 26715413 |
| 7747 | 5 | 0.9946 | Hydrothermal pre-treatment followed by anaerobic digestion for the removal of tylosin and antibiotic resistance agents from poultry litter. Hydrothermal pretreatment (HPT) followed by anaerobic digestion (AD) is an alternative for harvesting energy and removing organic contaminants from sewage sludge and animal manure. This study investigated the use, in an energetically sustainable way, of HPT and AD, alone or combined, to produce methane and remove tylosin and antimicrobial resistance genes (ARG) from poultry litter (PL). The results showed that HPT at 80 °C (HPT80), followed by single-stage AD (AD-1S), led to the production of 517.9 ± 4.7 NL CH(4) kg VS(-1), resulting in 0.11 kWh kg PL(-1) of electrical energy and 0.75 MJ kg PL(-1) of thermal energy, thus supplying 33.6% of the energy spent on burning firewood at a typical farm. In this best-case scenario, the use of HPT alone reduced tylosin concentration from PL by 23.6%, while the process involving HPT followed by AD-1S led to the removal of 91.6% of such antibiotic. The combined process (HPT80 + AD-1S), in addition to contributing to reduce the absolute and relative abundances of ARG ermB (2.13 logs), intI1 (0.39 logs), sul1 (0.63 logs), and tetA (0.74 logs), led to a significant removal in the relative abundance of tylosin-resistant bacteria present in the poultry litter. | 2023 | 36648713 |
| 7989 | 6 | 0.9946 | Feasibility of sulfate-calcined eggshells for removing pathogenic bacteria and antibiotic resistance genes from landfill leachates. High abundance of human pathogen and antibiotic resistance genes (ARGs) in landfill leachate has become an emerging threat against human health. Therefore, sulfate- and calcination-modified eggshells as green agricultural bioresource were applied to test the feasibility of removing pathogenic bacteria and ARGs from leachate. The highest removal of Escherichia coli (E. coil) and gentamycin resistant gene (gmrA) from artificial contaminated landfill leachate was achieved by the application of eggshell with combined treatment of sulfate and calcination. The 16S and gmrA gene copies of E. coil declined significantly from 1.78E8±8.7E6 and 4.12E8±5.9E6 copies mL(-1) to 1.32E7±2.6E6 and 2.69E7±7.2E6 copies mL(-1), respectively, within 24h dynamic adsorption equilibrium process (p<0.05). Moreover, according to the Langmuir kinetic model, the greatest adsorption amount (1.56×10(9) CFU E. coil per gram of modified eggshells) could be obtained at neutral pH of 7.5. The optimal adsorption eggshells were then screened to the further application in three typical landfill leachates in Nanjing, eastern China. Significant decrease in species and abundance of pathogenic bacteria and ARGs (tet, sul, erm, qnr, and ampC) indicated its great efficiency to purify landfill leachates. This study demonstrated that sulfate-calcined eggshells can be an environmentally-friendly and highly efficient bioadsorbent to the management of reducing dissemination risk of pathogen and ARGs in landfill leachate. | 2017 | 28343745 |
| 8105 | 7 | 0.9946 | Refluxing mature compost to replace bulking agents: A low-cost solution for suppressing antibiotic resistance genes rebound in sewage sludge composting. Antibiotic resistance genes (ARGs) rebounding during composting cooling phase is a critical bottleneck in composting technology that increased ARGs dissemination and application risk of compost products. In this study, mature compost (MR) was used as a substitute for rice husk (RH) to mitigate the rebound of ARGs and mobile genetic elements (MGEs) during the cooling phase of sewage sludge composting, and the relationship among ARGs, MGEs, bacterial community and environmental factors was investigated to explore the key factor influencing ARGs rebound. The results showed that aadD, blaCTX-M02, ermF, ermB, tetX and vanHB significantly increased 4.76-32.41 times, and the MGEs rebounded by 38.60% in the cooling phase of RH composting. Conversely, MR reduced aadD, tetM, ermF and ermB concentrations by 59.49-98.58%, and reduced the total abundance of ARGs in the compost product by 49.32% compared to RH, which significantly restrained ARGs rebound. MR promoted secondary high temperature inactivation of potential host bacteria, including Ornithinibacter, Rhizobiales and Caldicoprobacter, which could harbor aadE, blaCTX-M02, and blaVEB. It also reduced the abundance of lignocellulose degrading bacteria of Firmicutes, which were potential hosts of aadD, tetX, ermF and vanHB. Moreover, MR reduced moisture and increased oxidation reduction potential (ORP) that promoted aadE, tetQ, tetW abatement. Furthermore, MR reduced 97.36% of total MGEs including Tn916/1545, IS613, Tp614 and intI3, which alleviated ARGs horizontal transfer. Overall finding proposed mature compost reflux as bulking agent was a simple method to suppress ARGs rebound and horizontal transfer, improve ARGs removal and reduce composting plant cost. | 2025 | 39798649 |
| 7997 | 8 | 0.9945 | Survival of Antibiotic Resistant Bacteria and Horizontal Gene Transfer Control Antibiotic Resistance Gene Content in Anaerobic Digesters. Understanding fate of antibiotic resistant bacteria (ARB) vs. their antibiotic resistance genes (ARGs) during wastewater sludge treatment is critical in order to reduce the spread of antibiotic resistance through process optimization. Here, we spiked high concentrations of tetracycline-resistant bacteria, isolated from mesophilic (Iso M1-1-a Pseudomonas sp.) and thermophilic (Iso T10-a Bacillus sp.) anaerobic digested sludge, into batch digesters and monitored their fate by plate counts and quantitative polymerase chain reaction (QPCR) of their corresponding tetracycline ARGs. In batch studies, spiked ARB plate counts returned to baseline (thermophilic) or 1-log above baseline (mesophilic) while levels of the ARG present in the spiked isolate [tet(G)] remained high in mesophilic batch reactors. To compare results under semi-continuous flow conditions with natural influent variation, tet(O), tet(W), and sul1 ARGs, along with the intI1 integrase gene, were monitored over a 9-month period in the raw feed sludge and effluent sludge of lab-scale thermophilic and mesophilic anaerobic digesters. sul1 and intI1 in mesophilic and thermophilic digesters correlated positively (Spearman rho = 0.457-0.829, P < 0.05) with the raw feed sludge. There was no correlation in tet(O) or tet(W) ratios in raw sludge and mesophilic digested sludge or thermophilic digested sludge (Spearman rho = 0.130-0.486, P = 0.075-0.612). However, in the thermophilic digester, the tet(O) and tet(W) ratios remained consistently low over the entire monitoring period. We conclude that the influent sludge microbial composition can influence the ARG content of a digester, apparently as a result of differential survival or death of ARBs or horizontal gene transfer of genes between raw sludge ARBs and the digester microbial community. Notably, mesophilic digestion was more susceptible to ARG intrusion than thermophilic digestion, which may be attributed to a higher rate of ARB survival and/or horizontal gene transfer between raw sludge bacteria and the digester microbial community. | 2016 | 27014196 |
| 7996 | 9 | 0.9945 | A sludge bulking wastewater treatment plant with an oxidation ditch-denitrification filter in a cold region: bacterial community composition and antibiotic resistance genes. Bacterial community structure of activated sludge directly affects the stable operation of WWTPS, and these bacterial communities may carry a variety of antibiotic resistance genes (ARGs), which is a threat to the public health. This study employed 16S rRNA gene sequencing and metagenomic sequencing to investigate the bacterial community composition and the ARGs in a sludge bulking oxidation ditch-denitrification filter WWTP in a cold region. The results showed that Trichococcus (20.34%), Blautia (7.72%), and Faecalibacterium (3.64%) were the main bacterial genera in the influent. The relative abundances of norank_f_Saprospiraceae and Candidatus_Microthrix reached 10.24% and 8.40%, respectively, in bulking sludge, and those of norank_f_Saprospiraceae and Candidatus_Microthrix decreased to 6.56 and 7.10% after the anaerobic tank, indicating that the anaerobic tank had an inhibitory effect on filamentous bacteria. After 20 mJ/cm(2) UV disinfection, about 540 bacterial genera, such as Romboutsia (7.99%), Rhodoferax (7.98%), and Thermomonas (4.13%), could still be detected in the effluent. The ARGs were 345.11 ppm in the influent and 11.20 ppm in the effluent; 17 subtypes, such as sul1, msrE, aadA5, ErmF, and tet(A), could be detected throughout the entire process. These ARG subtypes were persistent ARGs with a high health risk. Network analysis indicated that the changes in filamentous bacteria norank_f_Saprospiraceae abundance mainly contributed to the abundance shift of MexB, and Acinetobacter mainly increased the abundance of drfA1. These results above will provide theoretical support for the sludge bulking and ARGs controls of WWTPs in cold regions. | 2023 | 36495431 |
| 7213 | 10 | 0.9944 | Distribution characteristics of antibiotic resistant bacteria and genes in fresh and composted manures of livestock farms. Livestock manure is a major reservoir of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs). This study investigated the distribution characteristics of ARB, ARGs in fresh and composted manures of traditional breading industry in rural areas in China. Samples collected were naturally piled without professional composting, and will be applied to farmland. The real-time quantitative polymerase chain reaction (qPCR) results showed the presence of ten target ARGs and two mobile genetic elements (MGEs) in the tested manure samples. The relative abundance of tetracycline and sulfonamide resistance genes (TRGs and SRGs) was generally higher than that of macrolide resistance genes (MRGs), followed by quinolone resistance genes (QRGs). There were significant positive correlations between the abundance of sul1, sul2, tetW and MGEs (intl1, intl2). In addition, the distribution of target ARGs was associated with the residual concentrations of doxycycline (DOX), sulfamethazine (SM2), enrofloxacin (ENR) and tylosin (TYL). Overall, a total of 24 bacterial genera were identified. The resistance rates of ARB were 17.79%-83.70% for SM2, followed 0.40%-63.77% for TYL, 0.36%-43.90% for DOX and 0.00%-13.36% for ENR, which showed a significant dose-effect. This study also demonstrated that the abundance of clinically relevant ARB and ARGs in chicken, swine and cow fresh manures significantly greater than that in composted manures, and chicken and swine manures had higher proportion of ARB and higher abundance of ARGs than that in cow manures. | 2019 | 31756854 |
| 8113 | 11 | 0.9944 | Fate of antibiotic resistance genes in mesophilic and thermophilic anaerobic digestion of chemically enhanced primary treatment (CEPT) sludge. Anaerobic digestion (AD) of chemically enhanced primary treatment (CEPT) sludge and non-CEPT (conventional sedimentation) sludge were comparatively operated under mesophilic and thermophilic conditions. The highest methane yield (692.46±0.46mL CH(4)/g VS(removed) in CEPT sludge) was observed in mesophilic AD of CEPT sludge. Meanwhile, thermophilic conditions were more favorable for the removal of total antibiotic resistance genes (ARGs). In this study, no measurable difference in the fates and removal of ARGs and class 1 integrin-integrase gene (intI1) was observed between treated non-CEPT and CEPT sludge. However, redundancy analysis indicated that shifts in bacterial community were primarily accountable for the variations in ARGs and intI1. Network analysis further revealed potential host bacteria for ARGs and intI1. | 2017 | 28797965 |
| 8033 | 12 | 0.9944 | Fate of pirlimycin and antibiotic resistance genes in dairy manure slurries in response to temperature and pH adjustment. Quantifying the fate of antibiotics and antibiotic resistance genes (ARGs) in response to physicochemical factors during storage of manure slurries will aid in efforts to reduce the spread of resistance when manure is land-applied. The objectives of this study were to determine the effects of temperature (10, 35, and 55 °C) and initial pH (5, 7, 9, and 12) on the removal of pirlimycin and prevalence of ARGs during storage of dairy manure slurries. We collected and homogenized feces and urine from five lactating dairy cows treated with pirlimycin and prepared slurries by mixing manure and sterile water. Aliquots (200 mL) of slurry were transferred and incubated in 400 mL glass beakers under different temperatures (10, 35, and 55 °C) or initial pH (5, 7, 9, and 12). Pirlimycin concentration and abundances of 16S rRNA, mefA, tet(W), and cfxA as indicators of total bacteria and ARGs corresponding to macrolide, tetracycline, and β-lactam resistance, respectively, were analyzed during manure incubation. The thermophilic environment (55 °C) increased the deconjugation and removal of pirlimycin, while the acidic shock at pH 5 increased deconjugation but inhibited removal of pirlimycin, suggesting that the chemical stability of pirlimycin could be affected by temperature and pH. The thermophilic environment decreased mefA relative abundance on day 7 and 28 (P = 0.02 and 0.04), which indicates that the bacteria that encoded mefA gene were not thermotolerant. Although mefA relative abundance was greater at the pH 9 shock than the rest of pH treatments on day 7 (P = 0.04), no significant pH effect was observed on day 28. The tet(W) abundance under initial pH 12 shock was less than other pH shocks on day 28 (P = 0.01), while no temperature effect was observed on day 28. There was no significant temperature and initial pH effect on cfxA abundance at any time point during incubation, implying that the bacteria that carrying cfxA gene are relatively insensitive to these environmental factors. Overall, directly raising temperature and pH can facilitate pirlimycin removal and decrease mefA and tet(W) relative abundances during storage of manure slurries. | 2020 | 32050366 |
| 8058 | 13 | 0.9944 | Effects of biochars on the fate of antibiotics and their resistance genes during vermicomposting of dewatered sludge. It is currently still difficult to decrease the high contents of antibiotics and their corresponding antibiotic resistance genes (ARGs) in sludge vermicompost. To decrease the environmental risk of vermicompost as a bio-fertilizer, this study investigated the feasibility of biochar addition to decrease the levels of antibiotics and ARGs during vermicomposting of dewatered sludge. To achieve this, 1.25% and 5% of corncob and rice husk biochars, respectively, were added to sludge, which was then vermicomposted by Eisenia fetida for 60 days. The sludge blended with corncob biochar showed increased decomposition and humification of organic matter. Higher biochar concentration promoted both the number and diversity of bacteria, and differed dominant genera. The level of antibiotics significantly decreased as a result of biochar addition (P < 0.05), and tetracycline was completely removed. Relative to the control without addition of biochars, ermF and tetX genes significantly decreased with corncob biochar treatment (P < 0.05). Rice husk biochar (5%) could effectively decrease sul-1 and sul-2 genes in vermicompost (P < 0.05). However, the abundance of the intI-1 gene increased with biochar concentration. This study suggests that biochar addition can lessen the antibiotic and ARG pollution in sludge vermicompost, depending on the type and concentration of biochars. | 2020 | 32388093 |
| 8067 | 14 | 0.9944 | Enhanced 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. | 2021 | 33582626 |
| 8053 | 15 | 0.9943 | 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 |
| 7792 | 16 | 0.9943 | Comparative removal of two antibiotic resistant bacteria and genes by the simultaneous use of chlorine and UV irradiation (UV/chlorine): Influence of free radicals on gene degradation. The research aimed to remove antibiotic resistance by the simultaneous use of UV irradiation and chlorine (UV/chlorine). The inactivations of tetracycline resistant bacteria (TRB) during chlorination, UV irradiation, and UV/chlorine was investigated and compared with those of amoxicillin resistant bacteria (AmRB). Similar examination was also conducted for comparing the removals of their resistant genes (i.e., tetM and blaTem). The removals of antibiotic resistance highly depended on chlorine doses and UV intensities. The sufficient chlorine dose (20 mg.L(-1)) in the chlorination and the UV/chlorine completely inactivated TRB and AmRB (>7.3 log), while the UV irradiation could not achieve the complete disinfection. Microorganisms resistant to different antibiotics exhibit different susceptibility to the disinfection processes. The removals of antibiotic resistant genes (i.e., tetM and blaTem) were more difficult than those of TRB and AmRB. The UV/chlorine was the greatest process for tetM and blaTem removals, followed by chlorination and UV irradiation, respectively. Chlorination decreased the tetM and blaTem by 0.40-1.45 log and 1.04-2.45 log, respectively. The blaTem gene was highly reactive to chlorine, compared with tetM. The UV irradiation caused the tetM and blaTem reductions by 0.32-0.91 log and 0.59-0.96 log, respectively. The UV/chlorine improved the tetM and blaTem removals by 0.98-3.20 log and 1.28-3.36 log, respectively. The •OH contributed to the fraction of tetM and blaTem removals by 48% and 19%, respectively. The effect of reactive chlorine species on the tetM and blaTem removals was minor. The pseudo 1st-order kinetic constants (k') for tetM and blaTem removals by the UV/chlorine were highest. The •OH enhanced the k' values by 120% and 20% for the tetM and blaTem removals, respectively. The study showed the potential use of UV/chlorine for controlling antibiotic resistance. | 2021 | 33059146 |
| 8015 | 17 | 0.9943 | Distribution, horizontal transfer and influencing factors of antibiotic resistance genes and antimicrobial mechanism of compost tea. Compost tea was alternatives of chemical pesticide for green agriculture, but there were no reports about antibiotic resistance genes (ARGs) in compost tea. This study investigated the effect of livestock manures, sewage sludge, their composting products and liquid fermentation on ARGs, mobile genetic elements (MGEs), metal resistance genes (MRGs) and antimicrobial properties of various compost tea. The results showed aerobic liquid fermentation reduced ARGs by 65.93 % and 45.20 % in the compost tea of chicken manure and sludge, enriched ARGs by 8.57 % and 37.41 % in the compost tea of pig manure and bovine manure, and increased MGEs and MRGs by 1.25 × 10(-5)-5.53 × 10(-3) and 2.03 × 10(-5)-2.03 × 10(-3) in the four compost tea. The correlation coefficient of tetracycline and sulfonamide resistance genes between compost product and compost tea were 0.98 and 0.91. aadA2-02, sul2 and tetX abundant in the compost tea were positively correlated with MGEs and MRGs. Furthermore, liquid fermentation enriched the potential host of tetracycline and vancomycin resistance genes. Tetracycline resistance genes occupied 62.7 % of total ARGs in the compost tea. Alcaligenes and Bacillus enriched by 0.78-39.31 % in the four compost tea, which metabolites had high antimicrobial activity. The potential host of ARGs accounted for 42.1 % bacteria abundance in the four compost tea. | 2022 | 35803190 |
| 8008 | 18 | 0.9942 | Reductions of bacterial antibiotic resistance through five biological treatment processes treated municipal wastewater. Wastewater treatment plants are hot spots for antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs). However, limited studies have been conducted to compare the reductions of ARB and ARGs by various biological treatment processes. The study explored the reductions of heterotrophic bacteria resistant to six groups of antibiotics (vancomycin, gentamicin, erythromycin, cephalexin, tetracycline, and sulfadiazine) and corresponding resistance genes (vanA, aacC1, ereA, ampC, tetA, and sulI) by five bench-scale biological reactors. Results demonstrated that membrane bioreactor (MBR) and sequencing batch reactor (SBR) significantly reduced ARB abundances in the ranges of 2.80∼3.54 log and 2.70∼3.13 log, respectively, followed by activated sludge (AS). Biological filter (BF) and anaerobic (upflow anaerobic sludge blanket, UASB) techniques led to relatively low reductions. In contrast, ARGs were not equally reduced as ARB. AS and SBR also showed significant potentials on ARGs reduction, whilst MBR and UASB could not reduce ARGs effectively. Redundancy analysis implied that the purification of wastewater quality parameters (COD, NH4 (+)-N, and turbidity) performed a positive correlation to ARB and ARGs reductions. | 2016 | 27384166 |
| 7761 | 19 | 0.9942 | Fate and removal of bacteria and antibiotic resistance genes in horizontal subsurface constructed wetlands: Effect of mixed vegetation and substrate type. This study aimed to investigate the influence of cropping method and substrate type on the fate and the removal of bacterial and antibiotic resistance genes (ARGs) indicators from primary wastewater by constructed wetlands (CWs) during startup and maturation stages. Four small-scale CWs differing in their plantation pattern (monoculture vs. polyculture) and substrate type were constructed and operated under field conditions. While for bacteria, the greatest impact of the cropping method and substrate type on removal was during the startup stage rather than the maturation stage, for ARGs, such impact was significant at both stages. During startup, the removal efficiencies of heterotrophic bacteria, fecal coliforms, E. coli, 16S rRNA genes and lacZ increased with the operation time. At maturation, the removal efficiencies were constant and were within the range of 89.2-99.4%, 93.7-98.9%, 89-98.8%, 94.1-99.6% and 92.9-98.7%, respectively. The removal efficiencies of intl1, tetM, intl1, sul1, ermB and total ARGs were also increased with the operation time. However, they were ARG type and configuration-dependent; at maturation they ranged between 50.7%-89.4%, 85.9%-97%, 49.6%-92.9%, 58.2%-96.7% and 79.9-94.3%, respectively. The tuff-filled serially planted CW was also the only one capable of removing these genes at similar high efficiency. Metagenomic analysis showed that none of the ARGs was among the most common ARGs in water and biofilm samples; rather most ARGs belonged to bacterial efflux transporter superfamilies. Although ARGs were removed, they were still detected in substrate biofilm and their relative concentrations were increased in the effluents. While the removal of both bacteria and ARGs was higher during summer compared to winter, the season had no effect on the removal pattern of ARGs. Hence, combination of the serial plantation with substrate having high surface area is a potential strategy that can be used to improve the performance of CWs. | 2021 | 33338689 |