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805800.9969Effects 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.202032388093
794010.9969Microplastics affect the ammonia oxidation performance of aerobic granular sludge and enrich the intracellular and extracellular antibiotic resistance genes. Microplastics (MPs) and antibiotic resistance genes (ARGs), as emerging pollutants, are frequently detected in wastewater treatment plants, and their threats to the environment have received extensive attentions. However, the effects of MPs on the nitrification of aerobic granular sludge (AGS) and the spread patterns of intracellular and extracellular ARGs (iARGs and eARGs) in AGS were still unknown. In this study, the responses of AGS to the exposure of 1, 10 and 100 mg/L of typical MPs (polyvinyl chloride (PVC), polyamide (PA), polystyrene (PS) and polyethylene (PE)) and tetracycline were focused on in 3 L nitrifying sequencing batch reactors. 10 mg/L MPs decreased the nitrification function, but nitrification could recover. Furthermore, MPs inhibited ammonia-oxidizing bacteria and enriched nitrite-oxidizing bacteria, leading partial nitrification to losing stability. PVC, PA and PS stimulated the secretion of extracellular polymeric substances and reactive oxygen species. PE had less negative effect on AGS than PVC, PA and PS. The abundances of iARGs and eARGs (tetW, tetE and intI1) increased significantly and the intracellular and extracellular microbial communities obviously shifted in AGS system under MPs stress. Potential pathogenic bacteria might be the common hosts of iARGs and eARGs in AGS system and were enriched in AGS and MPs biofilms.202133387747
810120.9969Enhanced removal of antibiotic resistance genes and mobile genetic elements during swine manure composting inoculated with mature compost. Livestock manure is a major source of antibiotic resistance genes (ARGs) that enter the environment. This study assessed the effects of inoculation with mature compost (MC) on the fates of ARGs and the bacterial community during swine manure composting. The results showed that MC prolonged the thermophilic period and promoted the decomposition of organic matter, which was due to the rapid growth and reproduction of thermophilic bacteria (Bacillus, Thermobifida, and Thermobacillus). MC significantly reduced the relative abundances of ARGs (1.02 logs) and mobile genetic elements (MGEs) (1.70 logs) after composting, especially sulfanilamide resistance genes. The total ARGs removal rate was 1.11 times higher in MC than the control. Redundancy analysis and structural equation modeling showed that horizontal gene transfer mediated by MGEs (ISCR1 and intI1) was the main direct factor related to the changes in ARGs during composting, whereas the C/N ratio and pH were the two most important indirect factors. Network analysis showed that members of Firmicutes comprising Romboutsia, Clostridisensu_stricto_1, and Terrisporobacter were the main bacterial hosts of ARGs and MGEs. MC reduced the risk of ARGs transmission by decreasing the abundances of bacterial hosts. Thus, MC is a promising strategy for reducing the proliferation risk of ARGs.202133858100
691730.9968Response characteristics of antibiotic resistance genes and bacterial communities during agricultural waste composting: Focusing on biogas residue combined with biochar amendments. This research investigated biogas residue and biochar addition on antibiotic resistance genes (ARGs), mobile genetic elements (MGEs), and changes in bacterial community during agricultural waste composting. Sequencing technique investigated bacterial community structure and ARGs, MGEs changes. Correlations among physicochemical factors, ARGs, MGEs, and bacterial community structure were determined using redundancy analysis. Results confirmed that biochar and biogas residue amendments effectively lowered the contents of ARGs and MGEs. The main ARGs detected was sul1. Proteobacteria and Firmicutes were the main host bacteria strongly associated with the dissemination of ARGs. The dynamic characteristics of the bacterial community were strongly correlated with pile temperature and pH (P < 0.05). Redundancy and network analysis revealed that nitrate, intI1, and Firmicutes mainly affected the in ARGs changes. Therefore, regulating these key variables would effectively suppress the ARGs spread and risk of compost use.202336657587
810940.9968The 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.202235063626
811050.9968Removal of chlortetracycline and antibiotic resistance genes in soil by earthworms (epigeic Eisenia fetida and endogeic Metaphire guillelmi). The impacts of two ecological earthworms on the removal of chlortetracycline (CTC, 0.5 and 15 mg kg(-1)) and antibiotic resistance genes (ARGs) in soil were explored through the soil column experiments. The findings showed that earthworm could significantly accelerate the degradation of CTC and its metabolites (ECTC) in soil (P < 0.05), with epigeic Eisenia fetida promoting degradation rapidly and endogeic Metaphire guillelmi exhibiting a slightly better elimination effect. Earthworms alleviated the abundances of tetR, tetD, tetPB, tetG, tetA, sul1, TnpA, ttgB and intI1 in soil, with the total relative abundances of ARGs decreasing by 35.0-44.2% in earthworm treatments at the 28th day of cultivation. High throughput sequencing results displayed that the structure of soil bacteria community was modified apparently with earthworm added, and some possible CTC degraders, Aeromonas, Flavobacterium and Luteolibacter, were promoted by two kinds of earthworms. Redundancy analysis demonstrated that the reduction of CTC residues, Actinobacteria, Acidobacteria and Gemmatimonadetes owing to earthworm stimulation was responsible for the removal of ARGs and intI1 in soil. Additionally, intI1 declined obviously in earthworm treatments, which could weaken the risk of horizontal transmission of ARGs. Therefore, earthworm could restore the CTC-contaminated soil via enhancing the removal of CTC, its metabolites and ARGs.202133798888
790560.9968Long-term responses of antibiotic resistance genes under high concentration of enrofloxacin, sulfadiazine and triclosan in aerobic granular sludge system. It is worth to reveal the long-term responses of antibiotic resistance genes (ARGs) in aerobic granular sludge (AGS) system exposed to high level enrofloxacin (ENR), sulfadiazine (SDZ) and triclosan (TCS). In present study, ppm level ENR, SDZ and TCS were added into three AGS reactors, respectively. ARGs in ENR and SDZ systems showed trends of increasing first and then decreasing, which were contrary to that in TCS system. 80%, 56% and 40% ARGs in ENR, SDZ and TCS systems, respectively, were enriched after loading, but several ARGs still kept high enrichment values after the withdrawn of loadings. The dominant bacteria in ENR (Flavobacterium), SDZ (Candidatus_Competibacter and Defluviicoccus) and TCS (Defluviicoccus) systems might contribute to the reductions of ARGs. IntI1 altered the overall ARGs profiles through horizontal gene transfer. The interactions of bacterial communities and environmental factors might be responsible for the different ARGs patterns in ENR, SDZ and TCS systems.202032470826
794270.9968Insight into effects of polyethylene microplastics in anaerobic digestion systems of waste activated sludge: Interactions of digestion performance, microbial communities and antibiotic resistance genes. The environmental risks of microplastics (MPs) have raised an increasing concern. However, the effects of MPs in anaerobic digestion (AD) systems of waste activated sludge (WAS), especially on the fate of antibiotic resistance genes (ARGs), have not been clearly understood. Herein, the variation and interaction of digestion performance, microbial communities and ARGs during AD process of WAS in the presence of polyethylene (PE) MPs with two sizes, PE MPs-180μm and PE MPs-1mm, were investigated. The results showed that the presence of PE MPs, especially PE MPs-1mm, led to the increased hydrolysis of soluble polysaccharides and proteins and the accumulation of volatile fatty acids. The methane production decreased by 6.1% and 13.8% in the presence of PE MPs-180μm and PE MPs-1mm, respectively. Together with this process, hydrolytic bacteria and acidogens were enriched, and methanogens participating in acetoclastic methanogenesis were reduced. Meanwhile, ARGs were enriched obviously by the presence of PE MPs, the abundances of which in PE MPs-180μm and PE MPs-1mm groups were 1.2-3.0 times and 1.5-4.0 times higher than that in the control by the end of AD. That was associated with different co-occurrence patterns between ARGs and bacterial taxa and the enrichment of ARG-hosting bacteria caused by the presence of PE MPs. Together these results suggested the adverse effects of PE MPs on performance and ARGs removal during AD process of WAS through inducing the changes of microbial populations.202235944782
810080.9968Composting temperature directly affects the removal of antibiotic resistance genes and mobile genetic elements in livestock manure. The high antibiotic resistance gene (ARGs) contents in livestock manure pose a potential risk to environment and human health. The heap composting with an ambient temperature and thermophilic composting are two methods for converting livestock manure into fertilizer. This study investigated the variations in ARGs and mobile genetic elements (MGEs) and revealed potential mechanisms for ARGs removal using the two composting methods. The ARGs abundance were enriched by 44-fold in heap composting, among them, the macrolide-resistance genes increased significantly. On the contrary, the ARGs were removed by 92% in thermophilic composting, among them, tetracycline-resistance genes decreased by 97%. The bacterial hosts of ARGs were associated with the variations of ARGs and MGEs. The tetO was correlated with the most diverse bacteria in heap composting, and Bacteroidetes was the major host bacteria. While tetT was correlated with the most diverse bacteria in thermophilic composting, and Proteobacteria was the major host bacteria. Structural equation models showed that the enrichment of ARGs in heap composting was mainly correlated with bacterial communities, whereas, the removal of ARGs in thermophilic composting was directly affect by MGEs. Composting temperature directly affected the variations in ARGs. Higher and lower temperatures significantly decreased and increased, respectively, ARGs and MGEs abundance levels.202235306090
794190.9968Microplastics accelerate nitrification, shape the microbial community, and alter antibiotic resistance during the nitrifying process. Microplastics (MPs) and antibiotic resistance genes (ARGs) are both emerging pollutants that are frequently detected in wastewater treatment plants. In this study, the effects of various MPs, including polyethylene (PE), polyvinyl chloride (PVC), and biodegradable polylactic acid (PLA), on nitrification performance, dominant microbial communities, and antibiotic resistance during nitrification were investigated. The results revealed that the addition of MPs increased the specific ammonia oxidation rate and specific nitrate production rate by 15.2 % - 15.5 % and 8.0 % - 11.6 %, respectively, via enrichment of nitrifying microorganisms, Nitrospira and Nitrosomonas. Moreover, ARGs were selectively enriched in nitrifying sludge and microplastic biofilms under stress from different MPs. Compared with PE-MPs (23.9 %) and PVC-MPs (21.4 %), exposure to PLA-MPs significantly increased intI1 abundance by 51.6 %. The results of the variance decomposition analysis implied that MPs and the microbial community play important roles in the behavior of ARGs. Network analysis indicated that Nitrosomonas and potentially pathogenic bacteria emerged as possible hosts, harboring ARGs and intI1 genes in the nitrifying sludge and microplastic biofilms. Critically, PLA-MPs were found to enrich both ARGs and potential pathogenic bacteria during nitrification, which should be considered in their promotion of application processes due to their biodegradability.202539740624
8113100.9968Fate 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 intI1.201728797965
6915110.9967Industrial-scale aerobic composting of livestock manures with the addition of biochar: Variation of bacterial community and antibiotic resistance genes caused by various composting stages. The presence of large amounts of antibiotic resistance genes (ARGs) in livestock manures poses an impending, tough safety risk to ecosystems. To investigate more comprehensively the mechanisms of ARGs removal from industrial-scale composting of livestock manure based on biochar addition, we tracked the dynamics of bacterial community and ARGs at various stages of aerobic composting of livestock manures with 10% biochar. There were no significant effects of biochar on the bacterial community and the profiles of ARGs. During aerobic composting, the relative abundance of ARGs and mobile genetic elements (MGEs) showed overall trends of decreasing and then increasing. The key factor driving the dynamics of ARGs was bacterial community composition, and the potential hosts of ARGs were Caldicoprobacter, Tepidimicrobium, Ignatzschineria, Pseudogracilibacillus, Actinomadura, Flavobacterium and Planifilum. The retention of the thermophilic bacteria and the repopulation of the initial bacteria were the dominant reasons for the increase in ARGs at maturation stage. Additionally, among the MGEs, the relative abundance of transposon gene was substantially removed, while the integron genes remained at high relative abundance. Our results highlighted that the suitability of biochar addition to industrial-scale aerobic composting needs to be further explored and that effective measures are needed to prevent the increase of ARGs content on maturation stage.202236162559
8054120.9967Effects 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.201931505392
6919130.9967Enhanced removal of antibiotic resistance genes during chicken manure composting after combined inoculation of Bacillus subtilis with biochar. This study explored the combined effects of Bacillus subtilis inoculation with biochar on the evolution of bacterial communities, antibiotic resistance genes (ARGs), and mobile genetic elements (MGEs) during the composting of chicken manure. The results showed that B. subtilis inoculation combined with biochar increased bacterial abundance and diversity as well as prolonged the compost thermophilic period. Promoted organic matter biodegradation and facilitated the organic waste compost humification process, reduced the proliferation of ARGs by altering the bacterial composition. Firmicutes and Actinobacteriota were the main resistant bacteria related to ARGs and MGEs. The decrease in ARGs and MGEs was associated with the reduction in the abundance of related host bacteria. Compost inoculation with B. subtilis and the addition of biochar could promote nutrient transformation, reduce the increase in ARGs and MGEs, and increase the abundance of beneficial soil taxa.202437778803
8124140.9967Effect of graphene and graphene oxide on antibiotic resistance genes during copper-contained swine manure anaerobic digestion. Copper is an important selectors for antibiotic resistance genes (ARGs) transfer because of metal-antibiotic cross-resistance and/or coresistance. Due to carbon-based materials' good adsorption capacity for heavy metals, graphene and graphene oxide have great potential to reduce ARGs abundance in the environment with copper pollution. To figure out the mechanics, this study investigated the effects of graphene and graphene oxide on the succession of ARGs, mobile genetic elements (MGEs), heavy metal resistance genes (HMRGs), and bacterial communities during copper-contained swine manure anaerobic digestion. Results showed that graphene and graphene oxide could reduce ARGs abundance in varying degrees with the anaerobic reactors that contained a higher concentration of copper. Nevertheless, graphene decreased the abundance of ARGs more effectively than graphene oxide. Phylum-level bacteria such as Firmicutes, Bacteroidetes, Spirochaetes, and Verrucomicrobiaat were significantly positively correlated with most ARGs. Network and redundancy analyses demonstrated that alterations in the bacterial community are one of the main factors leading to the changes in ARGs. Firmicutes, Bacteroidetes, and Spirochaetes were enriched lower in graphene reactor than graphene oxide in anaerobic digestion products, which may be the main reason that graphene is superior to graphene oxide in reduced ARGs abundance. Additionally, ARGs were close to HMRGs than MGEs in the treatments with graphene, the opposite in graphene oxide reactors. Therefore, we speculate that the reduction of HMRGs in graphene may contribute to the result that graphene is superior to graphene oxide in reduced ARGs abundance in anaerobic digestion.202336394812
8017150.9967Dose-Dependent Effect of Tilmicosin Residues on ermA Rebound Mediated by IntI1 in Pig Manure Compost. The impact of varying antibiotic residue levels on antibiotic resistance gene (ARG) removal during composting is still unclear. This study investigated the impact of different residue levels of tilmicosin (TIM), a common veterinary macrolide antibiotic, on ARG removal during pig manure composting. Three groups were used: the CK group (no TIM), the L group (246.49 ± 22.83 mg/kg TIM), and the H group (529.99 ± 16.15 mg/kg TIM). Composting removed most targeted macrolide resistance genes (MRGs) like ereA, ermC, and ermF (>90% removal), and reduced ermB, ermX, ermQ, acrA, acrB, and mefA (30-70% removal). However, ermA increased in abundance. TIM altered compost community structure, driving succession through a deterministic process. At low doses, TIM reduced MRG-bacteria co-occurrence, with horizontal gene transfer via intI1 being the main cause of ermA rebound. In conclusion, composting reduces many MRG levels in pig manure, but the persistence and rebound of genes like ermA reveal the complex interactions between composting conditions and microbial gene transfer.202541011454
8112160.9967Fate of antibiotic resistance bacteria and genes during enhanced anaerobic digestion of sewage sludge by microwave pretreatment. The fate of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) were investigated during the sludge anaerobic digestion (AD) with microwave-acid (MW-H), microwave (MW) and microwave-H2O2-alkaline (MW-H2O2) pretreatments. Results showed that combined MW pretreatment especially for the MW-H pretreatment could efficiently reduce the ARB concentration, and most ARG concentrations tended to attenuate during the pretreatment. The subsequent AD showed evident removal of the ARB, but most ARGs were enriched after AD. Only the concentration of tetX kept continuous declination during the whole sludge treatment. The total ARGs concentration showed significant correlation with 16S rRNA during the pretreatment and AD. Compared with unpretreated sludge, the AD of MW and MW-H2O2 pretreated sludge presented slightly better ARB and ARGs reduction efficiency.201626970692
8056170.9967Antibiotic resistance gene profiles and evolutions in composting regulated by reactive oxygen species generated via nano ZVI loaded on biochar. In this study, nano zero-valent iron loaded on biochar (BC-nZVI) was analyzed for its effects on antibiotic resistance genes (ARGs) in composting. The results showed that BC-nZVI increased reactive oxygen species (ROS) production, and the peak values of H(2)O(2) and OH were 22.95 % and 55.30 % higher than those of the control group, respectively. After 65 days, the relative abundances of representative ARGs decreased by 56.12 % in the nZVI group (with BC-nZVI added). An analysis of bacterial communities and networks revealed that Actinobacteria, Proteobacteria, and Firmicutes were the main hosts for ARGs, and BC-nZVI weakened the link between ARGs and host bacteria. Distance-based redundancy analysis showed that BC-nZVI altered the microbial community structure through environmental factors and that most ARGs were negatively correlated with ROS, suggesting that ROS significantly affected the relative abundance of ARGs. According to these results, BC-nZVI showed potential for decreasing the relative abundance of ARGs in composting.202337611721
8094180.9967Additive quality influences the reservoir of antibiotic resistance genes during chicken manure composting. Aerobic composting is commonly used to dispose livestock manure and is an efficient way to reduce antibiotic resistance genes (ARGs). Here, the effects of different quality substrates on the fate of ARGs were assessed during manure composting. Results showed that the total relative abundances of ARGs and intI1 in additive treatments were lower than that in control, and high quality treatment with low C/N ratio and lignin significantly decreased the relative abundance of tetW, ermB, ermC, sul1 and sul2 at the end of composting. Additionally, higher quality treatment reduced the relative abundances of some pathogens such as Actinomadura and Pusillimonas, and some thermotolerant degrading-related bacteria comprising Pseudogracilibacillus and Sinibacillus on day 42, probably owing to the change of composting properties in piles. Structural equation models (SEMs) further verified that the physiochemical properties of composting were the dominant contributor to the variations in ARGs and they could also indirectly impact ARGs by influencing bacterial community and the abundance of intI1. Overall, these findings indicated that additives with high quality reduced the reservoir of antibiotic resistance genes of livestock manure compost.202134139628
8021190.9967The profile of antibiotic resistance genes in pig manure composting shaped by composting stage: Mesophilic-thermophilic and cooling-maturation stages. The variation of antibiotic resistance genes (ARGs) and influential factors in pig manure composting were investigated by conducting simulated composting tests using four different supplement materials (wheat straw, corn straw, poplar sawdust and spent mushroom). The results show that the relative abundance of total ARGs increased by 0.19-1.61 logs after composting, and tetX, sulI, sulII, dfrA1 and aadA were the major contributors. The variations of ARG profiles and bacterial communities throughout the composting were clearly divided into mesophilic-thermophilic and cooling-maturation stages in all tests, while different supplement materials did not exert a noticeable influence. Network analysis demonstrated the diversity of bacterial hosts for ARGs, the existence of multiple antibiotic resistant bacteria, and the weak correlations between ARGs and physicochemical factors in the composting piles. Of note, integron intI1 and Mycobacterium (a potential pathogen) were positively correlated with eight and four ARGs, respectively, that displayed increased abundance after composting.202032109697