Impact of different manure-derived dissolved organic matters on the fate of arsenic-antibiotic in co-contaminated paddy soils. - Related Documents




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857401.0000Impact of different manure-derived dissolved organic matters on the fate of arsenic-antibiotic in co-contaminated paddy soils. Manure application increases the transfer risk of antibiotic resistance to farmland. Especially, its impact remains unclear when it occurs in arsenic (As)-contaminated paddy soils, which is considered as a global environmental problem. In this work, we investigated the fate of antibiotic resistance genes (ARGs) in As-antibiotic co-contaminated paddy soils under the application of manure from different sources (pig manure, cow dung, and chicken manure). Differences in the aliphatic carbon and electron-donating capacities of these dissolved organic matters (DOM) regulated the transformation of iron and As by both biotic and abiotic processes. The regulation by pig manure was stronger than that by cow dung and chicken manure. DOM regulation increased the abundance of As-related functional genes (arsC, arrA, aioA, and arsM) in the soil and accelerated the transformation of As speciation, the highest proportion of As(III) being 45%-61%. Meanwhile, the continuous selection pressure provided by the highly toxic As(III) increased the risk of ARGs and mobile genetic elements (MGEs) via horizontal gene transfer. As-resistant bacteria, including Bacillus, Geobacter, and Desulfitobacterium, were finally considered as potential host bacteria for ARGs and MGEs. In summary, this study clarified the synergistic mechanism of As-antibiotic on the fate of ARGs in co-contaminated paddy soils, and provided practical guidance for the proper application of organic fertilizers.202235491001
704210.9999Response of antibiotic resistance genes abundance by graphene oxide during the anaerobic digestion of swine manure with copper pollution. The pollution of various environments with antibiotic resistance genes (ARGs) is an urgent problem that needs to be addressed, especially in heavy metal-polluted environments. This study investigated the responses of ARGs and mobile genetic elements (MGEs) to the addition of graphene oxide (GO) to swine manure containing a high concentration copper during anaerobic digestion. The total copy numbers of ARGs and MGEs were significantly enhanced by the pressure due to Cu. GO significantly decreased the ARG and MGE copy numbers, where the low GO concentration performed better than the high GO concentration. Network analysis showed that most of the ARGs and MGEs co-occurred and they shared the same major potential host bacteria. The contributions of different factors to ARG abundances were assessed by redundancy analysis and MGEs had the most important effect on the fate of ARGs. Thus, GO may reduce the abundance of ARGs mainly by removing MGEs.201930445329
750720.9998Impact of different organic matters on the occurrence of antibiotic resistance genes in activated sludge. The occurrence of antibiotic resistance genes (ARGs) in various environments has drawn worldwide attention due to their potential risks. Previous studies have reported that a variety of substances can enhance the occurrence and dissemination of ARGs. However, few studies have compared the response of ARGs under the stress of different organic matters in biological wastewater treatment systems. In this study, seven organic pollutants were added into wastewater treatment bioreactors to investigate their impacts on the ARG occurrence in activated sludge. Based on high-throughput sequencing, it was found that the microbial communities and ARG patterns were significantly changed in the activated sludge exposed to these organic pollutants. Compared with the non-antibiotic refractory organic matters, antibiotics not only increased the abundance of ARGs but also significantly changed the ARG compositions. The increase of Gram-negative bacteria (e.g., Archangium, Prosthecobacter and Dokdonella) carrying ARGs could be the main cause of ARG proliferation. In addition, significant co-occurrence relationships between ARGs and mobile genetic elements were also observed in the sludge samples, which may also affect the ARG diversity and abundance during the organic matter treatment in the bioreactors. Overall, these findings provide new information for better understanding the ARG occurrence and dissemination caused by organic pollutants in wastewater treatment systems.202336522059
750530.9998A Review on the Degradation of Antibiotic Resistance Genes During Composting of Livestock Manure. As emerging pollutants, antibiotic resistance genes (ARGs) have been recognized as originating from diverse sources. Among these, the use of livestock feed and veterinary drugs was identified as the primary source of ARGs in livestock manure. ARGs were found to be widely distributed in global environments, particularly in agriculture-related soils, water bodies, and the atmosphere, posing potential threats to ecological environments and human health. This paper reviewed the degradation mechanisms of ARGs during aerobic composting of livestock manure and the safety evaluation of compost products. Aerobic composting was demonstrated to be an effective method for degrading ARGs, primarily through mechanisms such as high-temperature elimination of ARG-carrying microorganisms, reduction in host bacterial abundance, and inhibition of horizontal gene transfer. Factors including the physicochemical properties of the composting substrate, the use of additives, and the presence of antibiotic and heavy metal residues were shown to influence the degradation efficiency of ARGs, with compost temperature being the core factor. The safety of organic fertilizers encompassed multiple aspects, including heavy metal content, seed germination index, and risk assessments based on ARG residues. The analysis indicated that deficiencies existed in areas such as the persistence of thermotolerant bacteria carrying ARGs, the dissemination of extracellular antibiotic resistance genes (eARGs), and virus-mediated gene transfer. Future research should focus on (1) the removal of thermotolerant bacteria harboring ARGs; (2) the decomposition of eARGs or the blocking of their transmission pathways; (3) the optimization of ultra-high temperature composting parameters; and (4) the analysis of interactions between viruses and resistant hosts. This study reviews the mechanisms, influencing factors, and safety assessment of aerobic composting for degrading ARGs in livestock manure. It not only deepens the understanding of this important environmental biotechnology process but also provides a crucial knowledge base and practical guidance for effectively controlling ARG pollution, ensuring agricultural environmental safety, and protecting public health. Additionally, it clearly outlines the key paths for future technological optimization, thus holding significant implications for the environment, agriculture, and public health.202540863943
756140.9998Deciphering antibiotic resistome variations during nitrogen removal process transition under mixed antibiotics stress: Assembly process and driving factors. Antibiotic resistome, which encompasses all types of antibiotic resistance genes (ARGs) in a given environment, has received increasing attention in research on different wastewater treatment processes. However, the variation in antibiotic resistome during the transition from the full nitrification-denitrification to the shortcut nitrification-denitrification process remains unclear. In this study, a total of 269 targeted gene subtypes were identified, along with 108 genes were consistently present in all samples. The introduction of mixed antibioticsrapidly increased the abundance of corresponding and non-corresponding ARGs, as well as that of mobile genetic elements.The variations in of the antibiotic resistome were primarily driven by dissolved oxygen and nitrite accumulation rate. Moreover, 34 bacterial genera were identified as potential ARG hosts, with most denitrifiers considered as potential antibiotic-resistant bacteria, including Branchymonas, Rhodobacter, and Thauera. This study provides a method for controlling antibiotic resistance by regulating the changes in environmental variables and bacterial communities.202339492537
704150.9998Antibiotic and heavy metal resistance genes in sewage sludge survive during aerobic composting. Municipal sewage sludge has been generated in increasing amounts with the acceleration of urbanization and economic development. The nutrient rich sewage sludge can be recycled by composting that has a great potential to produce stabilized organic fertilizer and substrate for plant cultivation. However, little is known about the metals, pathogens and antibiotic resistance transfer risks involved in applying the composted sludge in agriculture. We studied changes in and relationships between heavy metal contents, microbial communities, and antibiotic resistance genes (ARGs), heavy metal resistance genes (HMRGs) and mobile genetic elements (MGEs) in aerobic composting of sewage sludge. The contents of most of the analyzed heavy metals were not lower after composting. The bacterial α-diversity was lower, and the community composition was different after composting. Firmicutes were enriched, and Proteobacteria and potential pathogens in the genera Arcobacter and Acinetobacter were depleted in the composted sludge. The differences in bacteria were possibly due to the high temperature phase during the composting which was likely to affect temperature-sensitive bacteria. The number of detected ARGs, HMRGs and MGEs was lower, and the relative abundances of several resistance genes were lower after composting. However, the abundance of seven ARGs and six HMRGs remained on the same level after composting. Co-occurrence analysis of bacterial taxa and the genes suggested that the ARGs may spread via horizontal gene transfer during composting. In summary, even though aerobic composting is effective for managing sewage sludge and to decrease the relative abundance of potential pathogens, ARGs and HMRGs, it might include a potential risk for the dissemination of ARGs in the environment.202336608829
703460.9998Meta-analysis reveals the processes and conditions of using biochar to control antibiotic resistance genes in soil. Soil is a significant reservoir of antibiotic resistance genes (ARGs) and an important habitat for pathogens associated with many clinical infections and plant disease outbreaks. Although scientists have found that biochar can reduce ARGs in soil, the understanding of how biochar removes soil ARGs and the influencing factors remains limited. Here, a meta-analysis of 65 published studies was conducted to illuminate the mechanisms through which biochar remediates ARG-contaminated soils. In biochar-amended soil, the antibiotic content significantly decreased by 24.1 %, while the abundances of mobile genetic elements and ARG host bacteria declined by 23.5 % and 12.1 %, respectively. The reduced antibiotic content, suppressed mobile genetic elements, and altered bacterial community structure collectively led to a 41.8 % reduction in soil ARG abundance. In addition, wood-derived biochar pyrolyzed at 300-500 °C exhibited a substantial advantage in the remediation of ARGs. Furthermore, biochar application decreased the abundance of ARGs in alkaline and neutral soil more markedly than that in acidic soil. The results of this research confirmed the positive mitigating effect of biochar on ARGs in soil, providing valuable insights for the prevention and control of ARG pollution.202540359860
703970.9998Profiles and key drivers of bacteria/phage co-mediated antibiotic resistance genes during swine manure composting amended with humic acid. Phages can promote the spread of antibiotic resistance genes (ARGs) in agricultural environments through transduction. However, studies on phage-mediated ARG profiles during composting have not been performed. This study investigated the effects of adding humic acid (HA) on the abundances of bacteria/phage co-mediated ARGs (b/pARGs) during swine manure composting and the key factors that affected the transmission of b/pARGs. The results showed that the addition of 5 % HA during composting could effectively reduce the absolute abundances of b/pARGs, inhibit the proliferation of pathogenic microorganisms (e.g., Corynebacterium and Streptococcus) that carried ARGs, and ultimately affect the fate of b/pARGs in the composting process by regulating key environmental factors to change the abundance of co-host bacteria. Overall, the findings of this study provided new information for understanding the main driving factors affecting the b/pARGs profile and provided a reference for the prevention and control of ARGs pollution during composting.202336774987
703080.9998Metagenomic profiling of antibiotic resistance genes/bacteria removal in urban water: Algal-bacterial consortium treatment system. Antibiotic resistance genes (ARGs) have exhibited significant ecological concerns, especially in the urban water that are closely associated with human health. In this study, with presence of exogenous Chlorella vulgaris-Bacillus licheniformis consortium, most of the typical ARGs and MGEs were removed. Furthermore, the relative abundance of potential ARGs hosts has generally decreased by 1-4 orders of magnitude, revealing the role of algal-bacterial consortium in cutting the spread of ARGs in urban water. While some of ARGs such as macB increased, which may be due to the negative impact of algicidal bacteria and algal viruses in urban water on exogenous C. vulgaris and the suppression of exogenous B. licheniformis by indigenous microorganisms. A new algal-bacterial interaction might form between C. vulgaris and indigenous microorganisms. The interplay between C. vulgaris and bacteria has a significant impact on the fate of ARGs removal in urban water.202438801952
745690.9998Anaerobic digestion of nitrogen rich poultry manure: Impact of thermophilic biogas process on metal release and microbial resistances. Poultry manure is a nitrogen rich fertilizer, which is usually recycled and spread on agricultural fields. Due to its high nutrient content, chicken manure is considered to be one of the most valuable animal wastes as organic fertilizer. However, when chicken litter is applied in its native form, concerns are raised as such fertilizers also include high amounts of antibiotic resistant pathogenic Bacteria and heavy metals. We studied the impact of an anaerobic thermophilic digestion process on poultry manure. Particularly, microbial antibiotic resistance profiles, mobile genetic elements promoting the resistance dissemination in the environment as well as the presence of heavy metals were focused in this study. The initiated heat treatment fostered a community shift from pathogenic to less pathogenic bacterial groups. Phenotypic and molecular studies demonstrated a clear reduction of multiple resistant pathogens and self-transmissible plasmids in the heat treated manure. That treatment also induced a higher release of metals and macroelements. Especially, Zn and Cu exceeded toxic thresholds. Although the concentrations of a few metals reached toxic levels after the anaerobic thermophilic treatment, the quality of poultry manure as organic fertilizer may raise significantly due to the elimination of antibiotic resistance genes (ARG) and self-transmissible plasmids.201727932039
7931100.9998The stress response of tetracycline resistance genes and bacterial communities under the existence of microplastics in typical leachate biological treatment system. Landfill leachate is an important source of microplastics (MPs) and antibiotic-resistance genes (ARGs). Here, in the presence of polystyrene MPs (PS-MPs) and polyethylene MPs (PE-MPs), the nitrogen and phosphorus removal effect and sludge structure performance were affected in an anaerobic-anoxic-aerobic system, a typical biological leachate treatment process. The abundance of tetracycline-resistance genes (tet genes) in biofilms on the two types of MP was significantly higher than that in the leachate and sludge, and the load on PE-MPs was higher than that on PS-MPs because of the porous structure of PE-MPs. Aging of the MPs increased their surface roughness and abundance of oxygen-containing functional groups and shaped the profile of ARGs in the MP biofilms. The biofilm biomass and growth rate on the two types of MP increased with the incubation time in the first 30 days, and was affected by environmental factors. Structural equation models and co-occurrence network analysis demonstrated that the MPs indirectly affected the spectrum of ARGs by affecting biofilm formation, and, to a lesser extent, had a direct impact on the selective enrichment of ARGs. We discuss the mechanisms of the relationships between MPs and ARGs in the leachate treatment system, which will have guiding significance for future research. Our data on the colonization of microorganisms and tet genes in MPs biofilms provide new evidence concerning the accumulation and transmission of these ARGs, and are important for understanding the mechanisms of MPs in spreading pollution.202439018858
8576110.9998Biochar can mitigate co-selection and control antibiotic resistant genes (ARGs) in compost and soil. Heavy metals (HMs) contamination raises the expression of antibiotic resistance (AR) in bacteria through co-selection. Biochar application in composting improves the effectiveness of composting and the quality of compost. This improvement includes the elimination and reduction of antibiotic resistant genes (ARGs). The use of biochar in contaminated soils reduces the bioaccessibility and bioavailability of the contaminants hence reducing the biological and environmental toxicity. This decrease in contaminant bioavailability reduces contaminants induced co-selection pressure. Conditions which favour reduction in HMs bioavailable fraction (BF) appear to favour reduction in ARGs in compost and soil. Biochar can prevent horizontal gene transfer (HGT) and can eliminate ARGs carried by mobile genetic elements (MGEs). This effect reduces maintenance and propagation of ARGs. Firmicutes, Proteobacteria, and Actinobacteria are the major bacteria phyla identified to be responsible for dissipation, maintenance, and propagation of ARGs. Biochar application rate at 2-10% is the best for the elimination of ARGs. This review provides insight into the usefulness of biochar in the prevention of co-selection and reduction of AR, including challenges of biochar application and future research prospects.202235663734
6985120.9998Elevated CO(2) Increased Antibiotic Resistomes in Seed Endophytes: Evidence from a Free-Air CO(2) Enrichment (FACE) Experiment. Climate warming affects antibiotic resistance genes (ARGs) in soil and the plant microbiome, including seed endophytes. Seeds act as vectors for ARG dissemination in the soil-plant system, but the impact of elevated CO(2) on seed resistomes remains poorly understood. Here, a free-air CO(2) enrichment system was used to examine the impact of elevated CO(2) on seed-associated ARGs and seed endophytic bacteria and fungi. Results indicated that elevated CO(2) levels significantly increased the relative abundance of seed ARGs and mobile genetic elements (MGEs), especially those related to beta-lactam resistance and MGEs. Increased CO(2) levels also influenced the composition of seed bacterial and fungal communities and the complexity of bacteria-fungi interactions. Fungi were more sensitive to changes in the CO(2) level than bacteria, with deterministic processes playing a greater role in fungal community assembly. Co-occurrence network analysis revealed a stronger correlation between fungi and ARGs compared to bacteria. The structure equation model (SEM) showed that elevated CO(2) directly influenced seed resistomes by altering bacterial composition and indirectly through bacteria-fungi interactions. Together, our work offers new insights into the effects of elevated CO(2) on antibiotic resistomes in the seed endosphere, highlighting their increased dissemination potential within soil-plant systems and the associated health risks in a changing environment.202439680930
7040130.9998The maturity period is the main stage of antibiotic resistance genes reduction in aerobic composting process of swine manure in sub-scale farms. This study was focused on the changes of antibiotic resistance genes (ARGs) and their potential host bacteria during the swine manure composting on sub-scale farms. Eight target ARGs increased 427% on average, with a trend of increase at early stage and decrease at later stage, and the main reduction stage appeared in maturity stage. The abundance of ARGs was mainly affected by the community succession of potential host bacteria. Composting could reduce the abundance of potential host bacteria of ARGs as well as pathogens such as Pseudomonas, and reduce the environmental risks of swine manure. N/C and S levels had a positive effect on the potential host of most ARGs. Prolonging the maturity period would inhibit the growth of potential host bacteria of ARGs during composting, therefore inhibiting the transmission of ARGs.202132971337
6931140.9998What role does organic fertilizer actually play in the fate of antibiotic resistome and pathogenic bacteria in planting soil? Organic fertilizer increase antibiotic resistance genes (ARGs) and bacterial pathogens have widely documented. However, how organic fertilizer is involved in changing soil ARGs and pathogenic bacteria after long-term (≥5 years) application remains unclear. Herein, the ARGs and pathogenic bacteria were compared in organic fertilized soils (AF) and non-fertilized soils (NF), and the contribution of input sources (organic fertilizer, irrigation water, air and background soil) on soil ARGs also was determined in this study. Results showed that the abundances of some ARGs, such as vanR and aac(6')-I in AF, were significantly higher than these of NF (p < 0.05). And a relatively higher abundance of potential pathogens, especially, Salmonella enterica and Stenotrophomonas maltophilia, in AF was observed. This indicated that organic fertilizer application can maintain a high level of some soil ARGs and pathogenic bacteria for at least 5 years. Traceability analysis unearthed that organic fertilizer application mainly increased its own contribution to soil ARGs from 1.16% to 9.05%, as well reduced the contribution of background soil, suggesting that the increase in soil ARGs may be partly attributable to organic fertilizer inputs. Notably, organic fertilizer application did not significantly alter the contribution ratio of input sources to microorganisms, but there was a clear change in the composition of soil microorganisms, which meant that the effect of the input source on the microorganism may emanate from other factors, rather than direct inputs. Subsequent structural equation demonstrated that organic fertilizer application significantly enhanced the effect of environmental factors on ARGs, and also indirectly increased the influence of communities on ARGs. Collectively, under the long-term fertilization, the role of organic fertilizers on soil ARGs not just stems from its own input, and also dominates the influence of environmental factors on ARGs. This study elucidates main causes for the difference in ARGs in AF vs. NF and enlightens actual role of organic fertilizer in them.202235623127
7560150.9998The effect of bacterial functional characteristics on the spread of antibiotic resistance genes in Expanded Granular Sludge Bed reactor treating the antibiotic wastewater. To explore the fate and spreading mechanism of antibiotics resistance genes (ARGs) in antibiotics wastewater system, a laboratory-scale (1.47 L) Expanded Granular Sludge Bed (EGSB) bioreactor was implemented. The operating parameters temperature (T) and hydraulic retention time (HRT) were mainly considered. This result showed the removal of ARGs and COD was asynchronous, and the recovery speed of ARGs removal was slower than that COD removal. The decreasing T was attributed to the high growth rate of ARGs host bacteria, while the shortened HRT could promote the horizontal and vertical gene transfer of ARGs in the sludge. The analysis result of potential bacterial host showed more than half of the potential host bacteria carried 2 or more ARGs and suggested an indirect mechanism of co-selection of multiple ARGs. Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) was used to investigate the functional characteristics of bacterial community. This result showed the bacterial functional genes contributed 40.41% to the abundance change of ARGs in the sludge, which was higher that of bacterial community. And the function genes of "aromatic hydrocarbon degradation", "Replication, recombination and repair proteins" and "Flagellar assembly" were mainly correlated with the transfer of ARGs in the sludge. This study further revealed the mechanism of ARGs spread in the EGSB system, which would provide new ideas for the development of ARGs reduction technology.202134488144
7562160.9998Nanoparticles and antibiotics stress proliferated antibiotic resistance genes in microalgae-bacteria symbiotic systems. The comprehensive effect of exogenous pollutants on the dispersal and abundance of antibiotic-resistance genes (ARGs) in the phycosphere, bacterial community and algae-bacteria interaction remains poorly understood. We investigated community structure and abundance of ARGs in free-living (FL) and particle-attached (PA) bacteria in the phycosphere under nanoparticles (silver nanoparticles (AgNPs) and hematite nanoparticles (HemNPs)) and antibiotics (tetracycline and sulfadiazine) stress using high-throughput sequencing and real-time quantitative PCR. Meanwhile, the intrinsic connection of algae-bacteria interaction was explored by transcriptome and metabolome. The results showed that the relative abundance of sulfonamide and tetracycline ARGs in PA and FL bacteria increased 103-129 % and 112-134 %, respectively, under combined stress of nanoparticles and antibiotics. Antibiotics have a greater effect on ARGs than nanoparticles at environmentally relevant concentrations. Proteobacteria, Firmicutes, and Bacteroidetes, as the primary potential hosts of ARGs, were the dominant phyla. Lifestyle, i.e., PA and FL, significantly determined the abundance of ARGs and bacterial communities. Moreover, algae can provide bacteria with nutrients (carbohydrates and amino acids), and can also produce antibacterial substances (fatty acids). This algal-bacterial interaction may indirectly affect the distribution and abundance of ARGs. These findings provide new insights into the distribution and dispersal of ARGs in microalgae-bacteria symbiotic systems.202336283215
6962170.9998The risk of viable but non-culturable (VBNC) enterococci and antibiotic resistance transmission during simulated municipal sludge composting. Sludge composting is a sludge resource utilization method that can reduce pollutants, such as pathogens. Enterococci are regarded as more reliable and conservative indicators of pathogen inactivation than fecal coliforms, which are typically used as indicators of fecal pollution. Non-spore pathogenic bacteria may enter a viable but non-culturable (VBNC) state during composting, leading to residual risk. The VBNC status of bacteria is related to their survival during composting. However, the survival mechanisms of enterococci during sludge composting remain unclear. Therefore, this study aimed to investigate the VBNC state of enterococci in different phases of simulated sludge composting and the fate of antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) during the composting process. This study is expected to provide a basis for subsequent exploration of possible methods to completely inactivate enterococci and reduce ARGs during sludge composting. Culturable enterococci were reduced in the thermophilic phase of sludge composting, but the proportion of VBNC subpopulation increased. It was reported for the first time that most VBNC enterococci were killed by extending the cooling phase of sludge compost, and by prolonging the cooling phase the types of ARG were reduced. However, there was a certain quantity (approximately 10(4)/g dry weight) of culturable and VBNC enterococci in the compost products. In addition, MGEs and ARGs exist in both bacteria and compost products, leading to the risk of spreading antibiotic-resistant bacteria and antibiotic resistance when sludge compost products are used.202438703551
6954180.9998Temporal effects of repeated application of biogas slurry on soil antibiotic resistance genes and their potential bacterial hosts. Biogas slurry, a liquid end product of animal manure fermentation, is widely used as fertilizer in crop fields. Land application may introduce antibiotics and related resistance genes from livestock production into agricultural soil. Nevertheless, changes in antimicrobial resistance in soil where biogas slurry has been repeatedly applied are not fully understood. In the present study, 13 veterinary antibiotics were analyzed in soils that were repeatedly sprayed with biogas slurry, and simultaneously, temporal changes in antibiotic resistance genes (ARGs) and bacterial community composition were investigated using a real-time quantitative PCR assay and MiSeq sequencing. Long-term repeated application of biogas slurry did not result in excessive accumulation of antibiotic residuals in the soil but increased the abundance of ARGs and facilitated ARG transfer among potential hosts. Although the quantitative PCR assay showed a decreasing trend for the relative abundance of ARGs over time, a relevance network analysis revealed highly complex bacteria-ARG co-occurrence after long-term application, which implied that repeated application might intensify horizontal gene transfer (HGT) of ARGs among different bacterial hosts in soil. The increased relative abundance of the intl1 gene supported the shift in ARG-bacteria co-occurrence. Furthermore, ordination analysis showed that the distributions of antibiotic resistance bacteria (ARB) and ARGs were closely related to application duration than to the influence of antibiotic residuals in the biogas slurry-treated soil environment. Additionally, natural level of ARG abundance in untreated soils indirectly suggested the presence/absence of antibiotics was not a key determinant causing the spread of antimicrobial resistance. This study provides improved insight into the effects of long-term repeated application of biogas slurry on the shift in ARG abundances and bacteria-ARG co-occurrence in soils, highlighting the need to focus on the influence of changed soil environment on the ARG transfer.202031818620
7523190.9998Transfer of antibiotic resistance genes from soil to wheat: Role of host bacteria, impact on seed-derived bacteria, and affecting factors. The transfer of antibiotic resistance genes (ARGs) from soils to plants is poorly understood, especially the role of host bacteria in soils and its impact on seed-derived bacteria. Wheat (Triticum aestivum L.) was thus used to fill the gap by conducting pot experiments, with target ARGs and bacterial community analyzed. Results showed that the relative abundances of target ARGs gradually decreased during transfer of ARGs from the rhizosphere soil to root and shoot. Host bacteria in the rhizosphere soil were the primary source of ARGs in wheat. The 38, 21, and 19 potential host bacterial genera of target ARGs and intI1 in the rhizosphere soil, root, and shoot were identified, respectively, and they mainly belonged to phylum Proteobacteria. The abundance of ARGs carried by pathogenic Corynebacterium was reduced in sequence. During transfer of ARGs from the rhizosphere soil to root and shoot, some seed-derived bacteria and pathogenic Acinetobacter obtained ARGs through horizontal gene transfer and became potential host bacteria. Furthermore, total organic carbon, available nitrogen of the rhizosphere soil, water use efficiency, vapor pressure deficit, and superoxide dismutase of plants were identified as the key factors affecting potential host bacteria transfer in soils to wheat. This work provides important insights into transfer of ARGs and deepens our understanding of potential health risks of ARGs from soils to plants.202337741386