Chemical fertilizers promote dissemination of ARGs in maize rhizosphere: An overlooked risk revealed after 37-year traditional agriculture practice. - Related Documents




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698701.0000Chemical fertilizers promote dissemination of ARGs in maize rhizosphere: An overlooked risk revealed after 37-year traditional agriculture practice. Bacterial communities in soil and rhizosphere maintain a large collection of antibiotic resistance genes (ARGs). However, few of these ARGs and antibiotic resistant bacteria (ARB) are well-characterized under traditional farming practices. Here we compared the ARG profiles of maize rhizosphere and their bulk soils using metagenomic analysis to identify the ARG dissemination and explored the potential impact of chemical fertilization on ARB. Results showed a relatively lower abundance but higher diversity of ARGs under fertilization than straw-return. Moreover, the abundance and diversity of MGEs were significantly promoted by chemical fertilizer inputs in the rhizosphere compared to bulk soil. Machine learning and bipartite networks identified three bacterial genera (Pseudomonas, Bacillus and Streptomyces) as biomarkers for ARG accumulation. Thus we cultured 509 isolates belonging to these three genera from the rhizosphere and tested their antimicrobial susceptibility, and found that multi-resistance was frequently observed among Pseudomonas isolates. Assembly-based tracking explained that ARGs and four class I integrons (LR134330, LS998783, CP065848, LT883143) were co-occurred among contigs from Pseudomonas sp. Chemical fertilizers may shape the resistomes of maize rhizosphere, highlighting that rhizosphere carried multidrug-resistant Pseudomonas isolates, which may pose a risk to animal and human health. This study adds knowledge of long-term chemical fertilization on ARG dissemination in farmland systems and provides information for decision-making in agricultural production and monitoring.202438844214
702610.9999Organic fertilizer potentiates the transfer of typical antibiotic resistance gene among special bacterial species. The propagation of antibiotic resistance genes (ARGs) in environments has evoked many attentions, however, how to identify their host pathogenic bacteria in situ remains a great challenge. Here we explored the bacterial host distribution and dissemination of a typical ARG, sul1 gene, in agricultural soils through the simultaneous detection of sul1 and its host 16S rRNA gene by emulsion paired isolation and concatenation PCR (epicPCR). Compared to chemical fertilizer, organic fertilizer (chicken manure) led to a higher prevalence of sul1 gene in the soil, and dominant bacterial hosts of sul1 gene were classified into Proteobacteria and Bacteroidetes phyla. Additionally, significant higher diversity of antibiotic resistance bacteria (ARB), higher rate of horizontal gene transfer (HGT), higher rate of mobile genetic elements (MGE) and higher proportion of pathogens were all observed in the treatment of organic fertilizer. This study alerts potential health risks of manure applications in agricultural soils.202235483268
698920.9999Viral Community and Virus-Associated Antibiotic Resistance Genes in Soils Amended with Organic Fertilizers. Antibiotic resistance is a global health concern. Long-term organic fertilization can influence the antibiotic resistome of agricultural soils, posing potential risks to human health. However, little is known about the contribution of viruses to the dissemination of antibiotic resistance genes (ARGs) in this context. Here, we profiled the viral communities and virus-associated ARGs in a long-term (over 10 years) organic fertilized field by viral metagenomic analysis. A total of 61,520 viral populations (viral operational taxonomic units, vOTUs) were retrieved, of which 21,308 were assigned at the family level. The viral community structures were significantly correlated with the bacterial community structures (P < 0.001) and the dosage of applied sewage sludge (r(2) = 0.782). A total of 16 unique ARGs were detected in soil viromes, and the number of virus-associated ARG subtypes was higher in sewage sludge treatments (except for 1 SS) than others. The network analysis showed that the application of the organic fertilizer increased the bacteria-virus interactions, suggesting that the chances of ARG exchange between viruses and their hosts may increase. Overall, our results provide a novel understanding about virus-associated ARGs and factors affecting the profile of viral community in fertilized soil.202134596377
695130.9998The vertical migration of antibiotic-resistant genes and pathogens in soil and vegetables after the application of different fertilizers. The prevalence of bacterial resistance caused by the application of animal manure has become an important environmental issue. Herein, the vertical migration of antibiotic resistance genes (ARGs) and pathogens in soil and vegetables after the application of different fertilizers was explored. The results showed that the application of composted manure considerably enhanced the abundance of most ARGs and pathogens, especially in surface soil and pakchoi roots. Moreover, the soil ARGs increased partially from log 1.93 to log 4.65 after the application of composted manure, and six pathogens were simultaneously detected. It was observed that the increase in soil depth decreased most ARGs and pathogens by log 1.04-2.24 and 53.98 %~85.54 %, respectively. This indicated that ARGs and pathogens still existed in the deep soil (80-100 cm). Moreover, total organic carbon had a significant influence on the pathogen distribution, whereas bacterial communities primarily drove the vertical migration of ARGs rather than environmental factors. Although most of the ARG-host associations observed in the surface soil were disappeared in deep soil as revealed by network analysis, some co-occurrence pattern still occurred in deep soil, suggesting that some ARGs might be carried to deep soil by their host bacteria. These results were novel in describing the vertical migration of ARGs in the environment after the application of different fertilizers, providing ideas for curbing their migration to crops.202234400159
688440.9998The changes in antibiotic resistance genes during 86 years of the soil ripening process without anthropogenic activities. This study aimed to reveal the baseline of natural variations in antibiotic resistance genes (ARGs) in soil without anthropogenic activities over the decades. Nine soil samples with different time of soil formation were taken from the Yancheng Wetland National Nature Reserve, China. ARGs and mobile genetic elements (MGEs) were characterized using metagenomic analysis. A total of 196 and 192 subtypes of ARGs were detected in bulk soil and rhizosphere, respectively. The diversity and abundance of ARGs were stable during 69 years probably due to the alkaline pH soil environment but not due to antibiotics. Increases in ARGs after 86 years were probably attributed to more migrant birds inhabited compared with other sampling sites. Multidrug was the most abundant type, and largely shared by soil samples. It was further shown that soil samples could not be clearly distinguished, suggesting a slow process of succession of ARGs in the mudflat. The variation partitioning analysis revealed that the ARG profile was driven by the comprehensive effects exhibited by the bacterial community, MGEs, and environmental factors. Besides, pathogenic bacteria containing ARGs mediated by migrant birds in the area with 86 years of soil formation history nearing human settlements needed special attention. This study revealed the slow variations in ARGs in the soil ripening process without anthropogenic activities over decades, and it provided information for assessing the effect of human activities on the occurrence and dissemination of ARGs.202133228990
698250.9998Viral Communities Suppress the Earthworm Gut Antibiotic Resistome by Lysing Bacteria on a National Scale. Earthworms are critical in regulating soil processes and act as filters for antibiotic resistance genes (ARGs). Yet, the geographic patterns and main drivers of earthworm gut ARGs remain largely unknown. We collected 52 earthworm and soil samples from arable and forest ecosystems along a 3000 km transect across China, analyzing the diversity and abundance of ARGs using shotgun metagenomics. Earthworm guts harbored a lower diversity and abundance of ARGs compared to soil, resulting in a stronger distance-decay rate of ARGs in the gut. Greater deterministic assembly processes of ARGs were found in the gut than in soil. The earthworm gut had a lower frequency of co-occurrence patterns between ARGs and mobile genetic elements (MGEs) in forest than in arable systems. Viral diversity was higher in the gut compared to soil and was negatively correlated with bacterial diversity. Bacteria such as Streptomyces and Pseudomonas were potential hosts of both viruses and ARGs. Viruses had negative effects on the diversity and abundance of ARGs, likely due to the lysis on ARG-bearing bacteria. These findings provide new insights into the variations of ARGs in the earthworm gut and highlight the vital role of viruses in the regulation of ARGs in the soil ecosystem.202439037720
738960.9998Temporal changes of antibiotic-resistance genes and bacterial communities in two contrasting soils treated with cattle manure. The emerging environmental spread of antibiotic-resistance genes (ARGs) and their subsequent acquisition by clinically relevant microorganisms is a major threat to public health. Animal manure has been recognized as an important reservoir of ARGs; however, the dissemination of manure-derived ARGs and the impacts of manure application on the soil resistome remain obscure. Here, we conducted a microcosm study to assess the temporal succession of total bacteria and a broad spectrum of ARGs in two contrasting soils following manure application from cattle that had not been treated with antibiotics. High-capacity quantitative PCR detected 52 unique ARGs across all the samples, with β-lactamase as the most dominant ARG type. Several genes of soil indigenous bacteria conferring resistance to β-lactam, which could not be detected in manure, were found to be highly enriched in manure-treated soils, and the level of enrichment was maintained over the entire course of 140 days. The enriched β-lactam resistance genes had significantly positive relationships with the relative abundance of the integrase intI1 gene, suggesting an increasing mobility potential in manure-treated soils. The changes in ARG patterns were accompanied by a significant effect of cattle manure on the total bacterial community compositions. Our study indicates that even in the absence of selective pressure imposed by agricultural use of antibiotics, manure application could still strongly impact the abundance, diversity and mobility potential of a broad spectrum of soil ARGs. Our findings are important for reliable prediction of ARG behaviors in soil environment and development of appropriate strategies to minimize their dissemination.201626712351
698870.9998Plant cultivar determined bacterial community and potential risk of antibiotic resistance gene spread in the phyllosphere. The global increased antibiotic resistance level in pathogenic microbes has posed a significant threat to human health. Fresh vegetables have been recognized to be an important vehicle of antibiotic resistance genes (ARGs) from environments to human beings. Phyllosphere ARGs have been indicated to be changed with plant species, yet the influence of plant cultivar on the phyllospheric resistome is still unclear. Here, we detected the ARGs and bacterial communities in the phyllosphere of two cultivars of cilantros and their corresponding soils using high-throughput quantitative PCR technique and bacterial 16S rRNA gene-based high-throughput sequencing, respectively. We further identified the potential bacterial pathogens and analyzed the effects of plant cultivar on ARGs, mobile genetic elements (MGEs), microbiome and potential bacterial pathogens. The results showed that the cultivars did not affect the ARG abundance and composition, but significantly shaped the abundance of MGEs and the composition structure of bacteria in the phyllosphere. The relative abundance of potential bacterial pathogens was significantly higher in the phyllosphere than that in soils. Mantel test showed that the ARG patterns were significantly correlated to the patterns of potential bacterial pathogens. Our results suggested that the horizontal gene transfer of ARGs in the phyllosphere might be different between the two cultivars of cilantro and highlighted the higher risk of phyllospheric microorganisms compared with those in soils. These findings extend our knowledge on the vegetable microbiomes, ARGs, and potential pathogens, suggesting more agricultural and hygiene protocols are needed to control the risk of foodborne ARGs.202336522081
741580.9998Transfer and accumulation of antibiotic resistance genes and bacterial pathogens in the mice gut due to consumption of organic foods. Over the last few decades, organic food demand has grown largely because of increasing personal health concerns. Organic farming introduces antibiotic resistance genes (ARGs) and antibiotic-resistant bacteria (ARB) into foods. However, potential effects of organic foods on the gut microbiome and ARGs have been overlooked. Using high-throughput quantitative PCR and 16S rRNA high-throughput sequencing technology, we examined 132 ARGs from major classes, eight transposase genes, universal class I integron-integrase gene (intI), clinical class I integron-integrase gene (cintI), and the bacterial community in mouse gut after 8 weeks with an either organic or inorganic lettuce and wheat diet. A total of 8 types of major ARGs and 10 mobile genetic elements (MGEs) were detected in mice gut, including tetracycline, multidrug, sulfonamide, aminoglycoside, beta-lactamase, chloramphenicol, MLSB and vancomycin resistance genes. We found that abundance and diversity of ARGs, mobile gene elements, and potential ARB in the gut increased with time after consumption of organic foods, whereas no significant changes were observed in inorganic treated groups. Moreover, MGEs, including IS613, Tp614 and tnpA_03 were found to play an important role in regulating ARG profiles in the gut microbiome following consumption of organic foods. Importantly, feeding organic food increased the relative abundance of the potentially antibiotic-resistant pathogens, Bacteroides and Streptococcus. Our results confirm that there is an increasing risk of ARGs and ARB in the gut microbiome, which highlights the importance of organic food industries taking into account the potential accumulation and transmission of ARGs as a risk factor.202438215844
688190.9998Spatiotemporal profiles and underlying mechanisms of the antibiotic resistome in two water-diversion lakes. Human-induced interventions have altered the local characteristics of the lake ecosystems through changes in hydraulic exchange, which in turn impacts the ecological processes of antibiotic resistance genes (ARGs) in the lakes. However, the current understanding of the spatiotemporal patterns and driving factors of ARGs in water-diversion lakes is still seriously insufficient. In the present study, we investigated antibiotic resistome in the main regulation and storage hubs, namely Nansi Lake and Dongping Lake, of the eastern part of the South-to-North Water Diversion project in Shandong Province (China) using a metagenomic-based approach. A total of 653 ARG subtypes belonging to 25 ARG types were detected with a total abundance of 0.125-0.390 copies/cell, with the dominance of bacitracin, multidrug, and macrolide-lincosamide streptogramin resistance genes. The ARG compositions were sensitive to seasonal variation and also interfered by artificial regulation structures along the way. Human pathogenic bacteria such as Acinetobacter calcoaceticus, Acinetobacter lwoffii, Klebsiella pneumoniae, along with the multidrug resistance genes they carried, were the focus of risk control in the two studied lakes, especially in summer. Plasmids were the key mobile genetic elements (MGEs) driving the horizontal gene transfer of ARGs, especially multidrug and sulfonamide resistance genes. The null model revealed that stochastic process was the main driver of ecological drift for ARGs in the lakes. The partial least squares structural equation model further determined that seasonal changes of pH and temperature drove a shift in the bacterial community, which in turn shaped the profile of ARGs by altering the composition of MGEs, antibacterial biocide- and metal-resistance genes (BMGs), and virulence factor genes (VFGs). Our results highlighted the importance of seasonal factors in determining the water transfer period. These findings can aid in a deeper understanding of the spatiotemporal variations of ARGs in lakes and their driving factors, offering a scientific basis for antibiotic resistance management.202439322056
6827100.9998Metagenomic profiles of planktonic bacteria and resistome along a salinity gradient in the Pearl River Estuary, South China. Estuarine ecosystems undergo pronounced and intricate changes due to the mixing of freshwater and saltwater. Additionally, urbanization and population growth in estuarine regions result in shifts in the planktonic bacterial community and the accumulation of antibiotic resistance genes (ARGs). The dynamic changes in bacterial communities, environmental factors, and carriage of ARGs from freshwater to seawater, as well as the complex interrelationships among these factors, have yet to be fully elucidated. Here, we conducted a comprehensive study based on metagenomic sequencing and full-length 16S rRNA sequencing, covering the entire Pearl River Estuary (PRE) in Guangdong, China. The abundance and distribution of the bacterial community, ARGs, mobile genetic elements (MGEs), and bacterial virulence factors (VFs) were analyzed on a site-by-site basis through sampling along the salinity gradient in PRE, from upstream to downstream. The structure of the planktonic bacterial community undergoes continuous changes in response to variations in estuarine salinity, with the phyla Proteobacteria and Cyanobacteria being dominant bacterial throughout the entire region. The diversity and abundance of ARGs and MGEs gradually decreased with the direction of water flow. A large number of ARGs were carried by potentially pathogenic bacteria, especially in Alpha-proteobacteria and Beta-proteobacteria. Multi-drug resistance genes have the highest abundance and subtypes in PRE. In addition, ARGs are more linked to some MGEs than to specific bacterial taxa and disseminate mainly by HGT and not by vertical transfer in the bacterial communities. Various environmental factors, such as salinity and nutrient concentrations, have a significantly impact on the community structure and distribution of bacteria. In conclusion, our results represent a valuable resource for further investigating the intricate interplay between environmental factors and anthropogenic disturbances on bacterial community dynamics. Moreover, they contribute to a better understanding of the relative impact of these factors on the dissemination of ARGs.202337211102
6826110.9998Impact of land use on antibiotic resistance genes and bacterial communities in rivers. River ecosystems support essential ecosystem functions and services, including supplying water for domestic, agricultural, and industrial activities, provisioning of hydropower and fisheries, supporting navigation and recreational activities, and regulating water quality. In recent decades, the presence and spread of antibiotic resistance genes (ARGs) have emerged as a key threat to ecosystem health and human well-being. Rivers that are surrounded by human-modified landscapes serve as primary repositories and sources of ARGs. However, our understanding of the relationship between the diversity of ARGs and land use remain limited. We collected 30 sediment samples from five rivers in Ningbo, China, and then classified the sampling sites into two groups (i.e., group A with low levels of human impacts and group B with intense human impact) based on land use in their upstream areas. In total, we found 31 types of ARGs and 148 phyla of bacteria in the samples. ARGs abundance had a positive relationship with the levels of anthropogenic activities, and exhibited significant difference between the two groups. Co-occurrence networks showed that the interrelationship between bacteria and ARGs was more complex in group B than in group A. Moreover, Structural Equation Modeling (SEM) revealed that anthropogenic activity not only posed direct effect on ARGs but also indirectly affected ARGs through bacteria. Our results underscore the profound impacts of land-use changes on the diversity of ARGs, bacteria communities, and their relationships, which highlight the need for integrating ARGs in river assessments in regions with human-dominated land use.202540154785
6965120.9998Metaphire guillelmi gut as hospitable micro-environment for the potential transmission of antibiotic resistance genes. Earthworm gut played an important role in the transformation of various contaminants in the soil environments. With the increasing application of organic fertilizer recently, the ingestion of antibiotics, antibiotic resistance bacteria (ARB), and antibiotic resistance genes (ARGs) made the earthworm gut a potential favorable micro-environment for the transmission of ARGs in the soil. In this work, the conventional plate incubation and high-throughput sequencing methods were both employed to investigate the composition of the cultivable and overall ARB/ARGs in the Metaphire guillelmi earthworm gut. A total of 87 cultivable isolates that resisted tetracycline (TC) and/or sulfadiazine (SD) were obtained, most of which belonged to phylum Firmicutes, genus Bacillus. Meanwhile, the counts of isolates with TC-SD dual resistance were higher than those with sole SD or TC resistance. Moreover, higher ARB counts and diversity were detected in the earthworm gut by high-throughput sequencing technique than those by the classical plate cultivation. Overall, the combination of conventional cultivable bacteria isolation and high-throughput sequencing methods provided a comprehensive understanding of the ARB composition in the earthworm gut. The results demonstrate that the earthworm gut is a hospitable micro-environment for ARB colonization. The potential role of earthworm intestinal ARB and ARGs proliferation in soil environments warrants further research.201930884260
6877130.9998Exploring urban coastal areas: Investigating the urban coastal areas as a reservoirs of antibiotic resistance Genes★. Antibiotic resistance genes (ARGs) have long served as adaptive defensive mechanisms among bacteria, enabling their survival and propagation in challenging environments. The consequences of inefficient wastewater treatment have culminated the emergence of untreatable and lethal extensively drug-resistant. To understand the relationship between wastewater effluent and marine ecosystems, we conducted a study to monitor the diversity and prevalence of common ARGs in Hong Kong's urban coastal areas at different seasons. Our findings revealed that sul 1 was the most abundant resistance gene, with an average relative abundance of 4.45 × 10(-2) per 16s rRNA gene copy. Moreover, temperature, dissolved oxygen, and salinity were key factors influencing seasonal variations in total ARGs abundance. The influence of environmental factors varied based on ARGs' association with Intl1, with Intl1-associated ARGs strongly correlating with temperature and dissolved oxygen. Notably, despite their abundance, sul1 and mphA exhibited similar correlations with both Intl1 and key environmental factors, suggesting these ARGs share a common dissemination mechanism. Moreover, the robust association between resistance genes and mobile genetic elements (MGE) could potentially act as a valuable indicator for assessing the efficacy of removing ARGs in wastewater treatment methods when operating under carefully optimized environmental parameters.202539642594
6846140.9998Antibiotic resistance genes in an urban river as impacted by bacterial community and physicochemical parameters. Antibiotic resistance genes (ARGs) in urban rivers are a serious public health concern in regions with poorly planned, rapid development. To gain insights into the predominant factors affecting the fate of ARGs in a highly polluted urban river in eastern China, a total of 285 ARGs, microbial communities, and 20 physicochemical parameters were analyzed for 17 sites. A total of 258 unique ARGs were detected using high-throughput qPCR, and the absolute abundance of total ARGs was positively correlated with total organic carbon and total dissolved nitrogen concentrations (P < 0.01). ARG abundance and diversity were greatly altered by microbial community structure. Variation partitioning analysis showed that the combined effects of multiple factors contributed to the profile and dissemination of ARGs, and variation of microbial communities was the major factor affecting the distribution of ARGs. The disparate distribution of some bacteria, including Bacteroides from mammalian gastrointestinal flora, Burkholderia from zoonotic infectious diseases, and Zoogloea from wastewater treatment, indicates that the urban river was strongly influenced by point-source pollution. Results imply that microbial community shifts caused by changes in water quality may lead to the spread of ARGs, and point-source pollution in urban rivers requires greater attention to control the transfer of ARGs between environmental bacteria and pathogens.201728864929
6885150.9998Abundant bacteria shaped by deterministic processes have a high abundance of potential antibiotic resistance genes in a plateau river sediment. Recent research on abundant and rare bacteria has expanded our understanding of bacterial community assembly. However, the relationships of abundant and rare bacteria with antibiotic resistance genes (ARGs) remain largely unclear. Here, we investigated the biogeographical patterns and assembly processes of the abundant and rare bacteria from river sediment at high altitudes (Lhasa River, China) and their potential association with the ARGs. The results showed that the abundant bacteria were dominated by Proteobacteria (55.4%) and Cyanobacteria (13.9%), while the Proteobacteria (33.6%) and Bacteroidetes (18.8%) were the main components of rare bacteria. Rare bacteria with a large taxonomic pool can provide function insurance in bacterial communities. Spatial distribution of persistent abundant and rare bacteria also exhibited striking differences. Strong selection of environmental heterogeneity may lead to deterministic processes, which were the main assembly processes of abundant bacteria. In contrast, the assembly processes of rare bacteria affected by latitude were dominated by stochastic processes. Abundant bacteria had the highest abundance of metabolic pathways of potential drug resistance in all predicted functional genes and a high abundance of potential ARGs. There was a strong potential connection between these ARGs and mobile genetic elements, which could increase the ecological risk of abundant taxa and human disease. These results provide insights into sedimental bacterial communities and ARGs in river ecosystems.202236406442
6984160.9998Seeds Act as Vectors for Antibiotic Resistance Gene Dissemination in a Soil-Plant Continuum. Though the evidence for antibiotic resistance spread via plant microbiome is mounting, studies regarding antibiotic resistome in the plant seed, a reproductive organ and important food resource, are still in their infancy. This study investigated the effects of long-term organic fertilization on seed bacterial endophytes, resistome, and their intergenerational transfer in the microcosm. A total of 99 antibiotic resistance genes (ARGs) and 26 mobile genetic elements (MGEs) were detected by high-throughput quantitative PCR. The amount of organic fertilizer applied was positively correlated to the number and relative abundance of seed-associated ARGs and MGEs. Moreover, the transmission of ARGs from the rhizosphere to the seed was mainly mediated by the shared bacteria and MGEs. Notably, the rhizosphere of progeny seedlings derived from seeds harboring abundant ARGs was found to have a higher relative abundance of ARGs. Using structural equation models, we further revealed that seed resistome and MGEs were key factors affecting the ARGs in the progeny rhizosphere, implying the seed was a potential resistome reservoir for rhizosphere soil. This study highlights the overlooked role of seed endophytes in the dissemination of resistome in the soil-plant continuum, and more attention should be paid to plant seeds as vectors of ARGs within the "One-Health" framework.202338078407
3177170.9998Metagenomic investigation of antibiotic resistance genes and resistant bacteria contamination in pharmaceutical plant sites in China. Pharmaceutical plant sites play a significant role in the dissemination of antibiotic resistance genes (ARGs) into the environment. It is imperative to comprehensively monitor of ARGs across various environmental media at these sites. This study focused on three pharmaceutical plants, two located in North China and one in South China. Through metagenomic approaches, we examined the composition, mobility potential, and bacterial hosts of ARGs in diverse media such as process water, groundwater, topsoil, soil cores, and pharmaceutical fermentation residues across diverse environmental matrices, including topsoil, soil cores, process water, groundwater, and pharmaceutical fermentation residues. We identified a wide array of ARGs, comprising 21 types and 740 subtypes, with process water exhibiting the highest abundance and diversity. Treatment processes varied in their efficacy in eliminating ARGs, and the clinically relevant ARGs should also be considered when evaluating wastewater treatment plant efficiency. Geographical distinctions in groundwater ARG distribution between northern and southern regions were observed. Soil samples from the three sites showed minimal impact from pharmaceutical activity, with vancomycin-resistance genes being the most prevalent. High levels of ARGs in pharmaceutical fermentation residues underscore the necessity for improved waste management practices. Metagenomic assembly revealed that plasmid-mediated ARGs were more abundant than chromosome-mediated ARGs. Metagenome-assembled genomes (MAGs) analysis identified 166 MAGs, with 62 harboring multiple ARGs. Certain bacteria tended to carry specific types of ARGs, revealing distinct host-resistance associations. This study enhances our understanding of ARG dissemination across different environmental media within pharmaceutical plants and underscores the importance of implementing strict regulations for effluent and residue discharge to control ARG spread.202438960118
6878180.9998Reduction in antimicrobial resistance in a watershed after closure of livestock farms. Natural environments play a crucial role in transmission of antimicrobial resistance (AMR). Development of methods to manage antibiotic resistance genes (ARGs) in natural environments are usually limited to the laboratory or field scale, partially due to the complex dynamics of transmission between different environmental compartments. Here, we conducted a nine-year longitudinal profiling of ARGs at a watershed scale, and provide evidence that restrictions on livestock farms near water bodies significantly reduced riverine ARG abundance. Substantial reductions were revealed in the relative abundance of genes conferring resistance to aminoglycosides (42%), MLSB (36%), multidrug (55%), tetracyclines (53%), and other gene categories (59%). Additionally, improvements in water quality were observed, with distinct changes in concentrations of dissolved reactive phosphorus, ammonium, nitrite, pH, and dissolved oxygen. Antibiotic residues and other pharmaceuticals and personal care products (PPCPs) maintain at a similarly low level. Microbial source tracking demonstrates a significant decrease in swine fecal indicators, while human fecal pollution remains unchanged. These results suggest that the reduction in ARGs was due to a substantial reduction in input of antibiotic resistant bacteria and genes from animal excreta. Our findings highlight the watershed as a living laboratory for understanding the dynamics of AMR, and for evaluating the efficacy of environmental regulations, with implications for reducing environmental risks associated with AMR on a global scale.202438925006
7671190.9998Predicting the abundance of metal resistance genes in subtropical estuaries using amplicon sequencing and machine learning. Heavy metals are a group of anthropogenic contaminants in estuary ecosystems. Bacteria in estuaries counteract the highly concentrated metal toxicity through metal resistance genes (MRGs). Presently, metagenomic technology is popularly used to study MRGs. However, an easier and less expensive method of acquiring MRG information is needed to deepen our understanding of the fate of MRGs. Thus, this study explores the feasibility of using a machine learning approach-namely, random forests (RF)-to predict MRG abundance based on the 16S rRNA amplicon sequenced datasets from subtropical estuaries in China. Our results showed that the total MRG abundance could be predicted by RF models using bacterial composition at different taxonomic levels. Among them, the relative abundance of bacterial phyla had the highest predicted accuracy (71.7 %). In addition, the RF models constructed by bacterial phyla predicted the abundance of six MRG types and nine MRG subtypes with substantial accuracy (R(2) > 0.600). Five bacterial phyla (Firmicutes, Bacteroidetes, Patescibacteria, Armatimonadetes, and Nitrospirae) substantially determined the variations in MRG abundance. Our findings prove that RF models can predict MRG abundance in South China estuaries during the wet season by using the bacterial composition obtained by 16S rRNA amplicon sequencing.202236068766