Antibiotic and heavy metal resistance genes in sewage sludge survive during aerobic composting. - Related Documents




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704101.0000Antibiotic 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
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
691620.9999Mobile genetic elements in potential host microorganisms are the key hindrance for the removal of antibiotic resistance genes in industrial-scale composting with municipal solid waste. During the municipal solid waste (MSW) composting, antibiotic resistance genes (ARGs) could be one of the concerns to hinder the application of MSW composting. However, the understanding of enrichment and dissemination of ARGs during the industrial-scale composting is still not clear. Hence, this study aimed to investigate the ARG distributions at different stages in an industrial-scale MSW composting plant. Seven target ARGs and four target mobile genetic elements (MGEs) and bacterial communities were investigated. The abundances of ARGs and MGEs increased during two aerobic thermophilic stages, but they decreased in most ARGs and MGEs after composting. Network analysis showed that potential host bacteria of ARGs were mainly Firmicutes and Actinobacteria. The reduction of potential host bacteria was important to remove ARGs. MGEs were an important factor hindering ARG removal. Water-extractable S and pH were two main physicochemical factors in the changes of microbial community and the abundance of ARGs.202031962245
695030.9999Ceftiofur in swine manure contributes to reducing pathogens and antibiotic resistance genes during composting. Aerobic composting is a common way for the disposal of feces produced in animal husbandry, and can reduce the release of antibiotic resistance genes (ARGs) from feces into the environment. In this study, we collected samples from two distinct treatments of swine manure compost with and without ceftiofur (CEF), and identified the ARGs, mobile genetic elements (MGEs), and bacterial community by metagenomic sequencing. The impacts of CEF on the bacterial community composition and fate of ARGs and MGEs were investigated. With increasing composting temperature and pH, the concentration of CEF in the manure decreased rapidly, with a degradation half-life of 1.12 d and a 100% removal rate after 10 d of aerobic composting. Metagenomics demonstrated that CEF in the manure might inhibit the growth of Firmicutes and Proteobacteria, thereby reducing some ARGs and MGEs hosted by these two bacteria, which was further confirmed by the variations of ARGs and MGEs. A further redundancy analysis suggested that pH and temperature are key environmental factors affecting ARG removal during composting, and intI1 and bacterial communities also have significant influence on ARG abundance. These results are of great significance for promoting the removal of some ARGs from animal manure by controlling some key environmental factors and the type of antibiotics used in animals.202438685300
704040.9999The 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
703950.9999Profiles 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
699960.9999Different impacts of manure and chemical fertilizers on bacterial community structure and antibiotic resistance genes in arable soils. Both manure and chemical fertilizers are widely used in modern agriculture. However, the impacts of different fertilizers on bacterial community structure and antibiotic resistance genes (ARGs) in arable soils still remain unclear. In this study, high-throughput sequencing and quantitative PCR were employed to investigate the bacterial community structure, ARGs and mobile genetic elements (MGEs) influenced by the application of different fertilizers, including chemical fertilizers, piggery manure and straw ash. The results showed that the application of fertilizers could significantly change the soil bacterial community and the abundance of Gaiella under phylum Actinobacteria was significantly reduced from 12.9% in unfertilized soil to 4.1%-7.4% in fertilized soil (P < 0.05). It was also found that the application of manure could cause a transient effect on soil resistome composition and the relative abundance of ARGs increased from 7.37 ppm to 32.10 ppm. The abundance of aminoglycoside, sulfonamide and tetracycline resistance genes greatly increased after manure fertilization and then gradually returned to normal levels with the decay of some intestinal bacteria carrying ARGs. In contrast, the application of chemical fertilizers and straw ash significantly changed the bacterial community structure but exerted little effect on soil resistome. Overall, the results of this study illustrated the different effects of different fertilizers on the soil resistome and revealed that the changes of soil resistome induced by manure application mainly resulted from alteration of bacteria community rather than the horizontal gene transfer.201728898777
698170.9999Decline in the Relative Abundance of Antibiotic Resistance Genes in Long-Term Fertilized Soil and Its Driving Factors. The changes in antibiotic resistance genes (ARGs) in long-term fertilized soil remain controversial. We aimed to analyze the variation characteristics of ARGs in long-term fertilized soil using metagenomic sequencing. The relative abundance of ARGs did not increase significantly after 7 years of fertilization. However, a clear decline in the relative abundance of ARGs was observed compared to the data from the 4th year. Microbial adaptation strategies in response to changes in the ARG abundance were associated with shifts in microbiome composition and function. Among these, bacterial abundance was the primary driving factor. Additionally, total heavy metal content might serve as the most significant co-selective pressure influencing ARG number. We believe that increasing the selective pressure from heavy metals and antibiotics might result in the loss of certain microbial species and a decrease in ARG abundance. This study provides novel insights into the variations of soil resistance genes under long-term fertilization.202540785530
703880.9999Interactions between fungi and bacteria hosts carrying MGEs is dominant for ARGs fate during manure mesophilic composting. The mycelial networks of fungi promote the interaction between the originally isolated bacteria, thereby potentially enhancing the exchange of nutrients and the horizontal transfer of genetic materials. However, the driving effect of fungi on antibiotic resistance genes (ARGs) during mesophilic facultative composting is still unclear. This study aims to elucidate the changes in ARGs and underlying mechanisms during the mesophilic composting of manure. Results indicated that reduction rates of ARGs in sheep and pig manure over a 90-day composting period were 34.68% and 60.10%, respectively. The sul1, sul2 and tetX were identified as recalcitrant ARGs in both composting treatments, with the additional unique recalcitrant gene addA observed in sheep manure. Fungal communities appeared to have a more significant influence on the cooperation between bacteria and fungi. Massive fungi interacted intensively with bacterial hosts carrying both ARGs and mobile genetic elements (MGEs). In sheep and pig manure, there were 53 and 38 potential bacterial hosts (genus level) carrying both ARGs and MGEs, associated close interactions with fungi. Structural equation modeling revealed that compost properties influence ARGs by affecting the abundance of core fungi and the hosts carrying MGEs, and that core fungi could also impact ARGs by influencing the bacterial hosts carrying MGEs. Core fungi have the potential to facilitate the horizontal transfer of ARGs by enhancing bacterial network interactions.202539764902
698390.9999Deciphering Potential Roles of Earthworms in Mitigation of Antibiotic Resistance in the Soils from Diverse Ecosystems. Earthworms are capable of redistributing bacteria and antibiotic resistance genes (ARGs) through soil profiles. However, our understanding of the earthworm gut microbiome and its interaction with the antibiotic resistome is still lacking. Here, we characterized the earthworm gut and soil microbiome and antibiotic resistome in natural and agricultural ecosystems at a national scale, and microcosm studies and field experiments were also employed to test the potential role of earthworms in dynamics of soil ARGs. The diversity and structure of bacterial communities were different between the earthworm gut and soil. A significant correlation between bacterial community dissimilarity and spatial distance between sites was identified in the earthworm gut. The earthworm gut consistently had lower ARGs than the surrounding soil. A significant reduction in the relative abundance of mobile genetic elements and dominant bacterial phylotypes that are the likely hosts of ARGs was observed in the earthworm gut compared to the surrounding soil, which might contribute to the decrease of ARGs in the earthworm gut. The microcosm studies and field experiments further confirmed that the presence of earthworms significantly reduced the number and abundance of ARGs in soils. Our study implies that earthworm-based bioremediation may be a method to reduce risks associated with the presence of ARGs in soils.202133977709
7507100.9999Impact 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
6927110.9999Manure application: A trigger for vertical accumulation of antibiotic resistance genes in cropland soils. The application of livestock manure increases the dissemination risk of antibiotic resistance genes (ARGs) in farmland soil environment. However, the vertical migration behavior and driving factor of ARGs in manured soil under swine manure application remains undefined. Here, the dynamics of ARGs, mobile genetic elements (MGEs) and bacterial communities in different soil depths (0 - 80 cm) with long-term swine manure application were tracked and conducted using real-time qPCR. Results showed that long-term application of swine manure remarkably facilitated the vertical accumulation of ARGs and MGEs, in particular that the relative abundance of bla(ampC) showed significant enrichment with increasing depth. ARGs abundance was similar in the three fields with long-term application of swine manure. (p＞0.05). Procrustes analysis indicated that microbial communities were the dominant drivers of ARGs variation in topsoil, and the changes of environmental factors played a vital role in vertical migration ARGs in cropland soils. Additionally, the variation patterns of high-risk ARGs (i.e., bla(ampC), bla(TEM-1)) were influenced by the dominant bacteria (Actinomycetes) and pH. This study illustrated that the swine manure application promoted the vertical migration of ARGs, including multidrug resistance determinants, highlighting the ecological risk caused by long-term manure application.202235483148
7043120.9999Antibiotic resistance gene transfer during anaerobic digestion with added copper: Important roles of mobile genetic elements. The abuse of heavy metals as feed additives in livestock is widespread and it might aggravate the spread of antibiotic resistance genes (ARGs) in the environment. However, the mechanisms that allow heavy metals to increase the transmission of ARGs in the environment remain unclear. Cu is the heavy metal present at the highest concentration in livestock manure, and thus Cu was selected to investigate the responses of ARGs to heavy metals. The effects of the microbial communities, mobile genetic elements (MGEs), and heavy metal resistance genes (HMRGs) on ARGs were determined in the presence of 75 and 227 mg L(-1) Cu in a swine manure anaerobic digestion (AD) system. In the AD products, the presence of residual Cu (75 and 227 mg L(-1)) increased the total ARGs, HMRGs, and some MGEs, and the higher Cu selected more ARGs than the lower Cu treatment. The results demonstrated that Cu could promote the co-selection of HMRGs, ARGs, and MGEs. The different levels of Cu did not change the bacterial community composition, but they influenced the abundances of bacteria during AD. Network analysis showed that the presence of Cu increased the co-occurrence of specific bacteria containing ARGs, HMRGs, and MGEs. Furthermore, the co-occurrence of MGEs and ARGs increased greatly compared with that of HMRGs and ARGs. Therefore, compared HMRGs, the increased MGEs had the main effect on increasing of ARGs.202032659562
6923130.9999Soil types influence the fate of antibiotic-resistant bacteria and antibiotic resistance genes following the land application of sludge composts. Sewage sludge was generally considered a significant reservoir of antibiotic resistance genes (ARGs) and could enter agricultural systems as fertilizer after composting. Soil types and the discrepancy of sludge composts could have influenced the fate of antibiotic-resistant bacteria (ARB) following the land application of sludge composts, which deserved to be clarified. Thus, the fate of ARB and ARGs following the land application of three types of sludge composts (A, B, and C) to three different soils (red soil, loess, and black soil) was investigated. The results showed that tetX, which was enriched the most during composting, did not affect the soil resistome, whereas tetG did. Soil types influenced the dynamics of ARB and ARGs significantly, whereas no significant difference was observed among compost types. The advantage of reducing ARGs during the composting process in compost B did not extend to land application. Land application of composts influenced the microbial community significantly at the early stage, but the microbial community returned to the control pattern gradually. Changes in the microbial community contributed more to the dynamics of ARGs in red and black soil compared with other factors, including co-selection from heavy metals, horizontal gene transfer, biomass and environmental factors, whereas horizontal gene transfer, reflected by intI1 levels, contributed the most in loess.201829793114
6954140.9999Temporal 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
6925150.9999Multiple driving factors contribute to the variations of typical antibiotic resistance genes in different parts of soil-lettuce system. The application of manure compost may cause the transmission of antibiotic resistance genes (ARGs) in agroecological environment, which poses a global threat to public health. However, the driving factors for the transmission of ARGs from animal manure to agroecological systems remains poorly understood. Here, we explored the spatiotemporal variation in ARG abundance and bacterial community composition as well as relative driving factors in a soil-lettuce system amended with swine manure compost. The results showed that ARGs abundance had different variation trends in soil, lettuce phylloplane and endophyere after the application of swine manure compost. The temporal variations of total ARGs abundance had no significant different in soil and lettuce phylloplane, while lettuce endosphere enriched half of ARGs to the highest level at harvest. There was a significant linear correlation between ARGs and integrase genes (IGs). In contrast to the ARGs variation trend, the alpha diversity of soil and phylloplane bacteria showed increasing trends over planting time, and endosphere bacteria remained stable. Correlation analysis showed no identical ARG-related genera in the three parts, but the shared Proteobacteria, Pseudomonas, Halomonas and Chelativorans, from manure compost dominated ARG profile in the soil-lettuce system. Moreover, redundancy analysis and structural equation modelling showed the variations of ARGs may have resulted from the combination of multiple driving factors in soil-lettuce system. ARGs in soil were more affected by the IGs, antibiotic and heavy metals, and bacterial community structure and IGs were the major influencing factors of ARG profiles in the lettuce. The study provided insight into the multiple driving factors contribute to the variations of typical ARGs in different parts of soil-lettuce system, which was conducive to the risk assessment of ARGs in agroecosystem and the development of effective prevention and control measures for ARGs spread in the environment.202134562788
7025160.9999Aerobic composting as an effective cow manure management strategy for reducing the dissemination of antibiotic resistance genes: An integrated meta-omics study. Livestock manure is considered as an important source for spreading antibiotic resistance genes (ARGs) into the environment, and therefore poses a direct threat to public health. Whereas the effects of reused manure on soil microbial communities and ARGs have been studied extensively, comprehensive characterizations of microbial communities and ARGs of manure produced by different management methods are not well understood. Here, we analyzed the fate of microbial communities and ARGs of cow manure treated by three conventional management strategies: aerobic composting, mechanical drying and precipitation, applying an integrated-omics approach combining metagenomics and metaproteomics. Integrated-omics demonstrated that composted manure contained the lowest diversity of microbial community and ARGs compared with manure treated by other two strategies. Quantitative PCR methods revealed that the abundances of ARGs were reduced by over 83 % after composting for 14 days, regardless of the season. Besides, the potential ARG hosts Acinetobacter and Pseudomonas dominating mechanical drying process were sharply decreased in abundances after composting. The significant co-occurrence networks among bacteria, ARGs and transposase gene tnpA-01 in composting samples indicated the important role of these bacteria in the dissemination of ARGs. These findings offer insight into potential strategies to control the spread of ARGs during livestock manure reuse.202031884359
6924170.9999Diversity of antibiotic resistance genes in soils with four different fertilization treatments. Although the enrichment of resistance genes in soil has been explored in recent years, there are still some key questions to be addressed regarding the variation of ARG composition in soil with different fertilization treatments, such as the core ARGs in soil after different fertilization treatments, the correlation between ARGs and bacterial taxa, etc. For soils after different fertilization treatments, the distribution and combination of ARG in three typical fertilization methods (organic fertilizer alone, chemical fertilizer alone, and conventional fertilizer) and non-fertilized soils were investigated in this study using high-throughput fluorescence quantitative PCR (HT-qPCR) technique. The application of organic fertilizers significantly increased the abundance and quantity of ARGs and their subtypes in the soil compared to the non-fertilized soil, where sul1 was the ARGs specific to organic fertilizers alone and in higher abundance. The conventional fertilizer application also showed significant enrichment of ARGs, which indicated that manure addition often had a more decisive effect on ARGs in soil than chemical fertilizers, and three bacteria, Pseudonocardia, Irregularibacter, and Castllaniella, were the key bacteria affecting ARG changes in soil after fertilization. In addition, nutrient factors and heavy metals also affect the distribution of ARGs in soil and are positively correlated. This paper reveals the possible reasons for the increase in the number of total soil ARGs and their relative abundance under different fertilization treatments, which has positive implications for controlling the transmission of ARGs through the soil-human pathway.202337928655
7551180.9999Microbial community evolution and fate of antibiotic resistance genes during sludge treatment in two full-scale anaerobic digestion plants with thermal hydrolysis pretreatment. Anaerobic digestion (AD) with thermal hydrolysis pretreatment is widely used as an efficient sludge treatment nowadays. However, the evolution of microbial community (especially for the archaea community), the fate of antibiotic resistance genes (ARGs), and their associations during such process in full-scale sludge treatment plants are rarely reported. Therefore, these scientific questions were explored at two full-scale sludge treatment plants through high-throughput sequencing and quantitative PCR. Results showed that Methanobacterium and Methanosphaera were the dominant archaea in thermal hydrolyzed sludge. The predominant bacteria in the sludge first shifted from nutrients removal functional bacteria to spore-forming bacteria after thermal hydrolysis, and then shifted to fermentative bacteria after AD. The full-scale plants could select ermB, ermF, mefA/E, qnrS and tetM. Though the bacteria and archaea biomass and community largely influenced the fate of ARGs, multiple linear regression analysis showed that the total ARGs were mainly affected by mobile genetic elements (MGEs).201931158777
6920190.9999Dynamics and key drivers of antibiotic resistance genes during aerobic composting amended with plant-derived and animal manure-derived biochars. Plant-derived and animal manure-derived biochars have been used to improve the quality of compost but the differences in their effects on antibiotic resistance genes (ARGs) during composting are unclear. This study selected two types of biochar (RB and PB) produced from abundant agricultural waste to be added to the compost. Adding plant-derived RB performed better in ARGs, mobile genetic elements, and human pathogenic bacteria removal during aerobic composting, whereas adding manure-derived PB even increased ARGs abundance. Vertical gene transfer was possibly the key mechanism for persistent ARGs, and easily removed ARGs were regulated by horizontal and vertical gene transfer. Adding plant-derived RB reduced the abundances of persistent ARG hosts (e.g., Pseudomonas and Longispora) and ARG-related metabolic pathways and genes. The higher nitrogen content of manure-derived PB may have promoted the proliferation of ARG hosts. Overall, adding manure-derived biochar during composting may not be the optimal option for eliminating ARGs.202235487450