Characteristics of airborne bacterial communities and antibiotic resistance genes under different air quality levels. - Related Documents




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704701.0000Characteristics of airborne bacterial communities and antibiotic resistance genes under different air quality levels. Pathogenic bacteria and antibiotic resistance genes (ARGs) in bioaerosols are major threats to human health. In this study, the microbial community structure and ARG distribution characteristics of airborne bacteria in total suspended particulates (TSP) and PM(2.5) were investigated under different air quality levels in Xinxiang, Central China. The results revealed that with the deterioration of air quality, the concentrations of airborne bacteria in both TSP and PM(2.5) decreased; however, the relative amounts of pathogenic bacteria increased. The predominant genera in pathogenic bacteria of Bacillus, Sphingomonas, Corynebacterium, Rhodococcus, and Staphylococcus were identified in both TSP and PM(2.5). Although the airborne bacteria concentrations and absolute abundances of ARGs in TSP were higher than those in PM(2.5) under identical air quality conditions, the bacterial community structure and relative amounts of pathogenic bacteria were similar. In addition, the relationship between environmental factors of ions, metal elements, and meteorological parameters and the community structures of airborne bacteria and pathogenic bacteria were also analyzed. The effects of soluble ions and metal elements on several dominant genera of total bacteria and pathogenic bacteria differed, probably due to the strong tolerance of pathogenic bacteria to harsh atmospheric environments Different subtypes of ARGs showed various distribution characteristics with variations in air quality. The deterioration of air quality can inhibit the dissemination of ARGs, as the minimum values of all ARGs and class 1 integrase intI1 were observed under Severely Polluted conditions. This study provides a comprehensive understanding of the effect of air pollution levels on the airborne bacteria community composition and ARG distribution.202235180669
704810.9999Airborne antibiotics, antimicrobial resistance, and bacterial pathogens in a commercial composting facility: Transmission and exposure risk. Multiple elements associated with antimicrobial resistance in compost may escape into the air during the composting process, including antibiotic resistance genes (ARGs), human pathogenic bacteria (HPBs), and even antibiotics. Although antibiotics play a critical role in the evolution of resistance in HPBs, no information is available on airborne antibiotics in composting facilities. In this study, we systematically quantified airborne antibiotics, ARGs, and HPBs in comparison with those in compost. The burden of antibiotics in the air reached 4.17 ± 2.71 × 10(2) ng/g, significantly higher than that in compost. The concentration of ARGs (10(2) copies/g) in air also increased compared with that in compost. Concentrations of target contaminants in air were affected by temperature, organic matter, and heavy metals. Co-occurrence network analysis revealed the connectivity and complexity of antibiotics, ARGs, and HPBs were greater in air than in compost. The maximum daily antibiotic intake dose was up to 1.18 × 10(-1)ng/d/kg, accompanied by considerable inhalation levels of ARGs and HPBs. Our results reveal the severity of airborne antimicrobial resistance (AMR) elements in composting facilities, highlight the non-negligible amount of antibiotics and their co-existence with ARGs and HPBs, and shed light on the potential role of airborne antibiotics in the evolution of environmental AMR.202439442303
684620.9999Antibiotic 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
683830.9999Seasonal variation characteristics of inhalable bacteria in bioaerosols and antibiotic resistance genes in Harbin. Bioaerosols have received extensive attention due to their impact on climate, ecological environment, and human health. This study aimed to reveal the driving factors that structure bacterial community composition and the transmission route of antibiotic resistance genes (ARGs) in PM(2.5). The results showed that the bacterial concentration in spring (8.76 × 10(5) copies/m(3)) was significantly higher than that in summer (1.03 × 10(5) copies/m(3)) and winter (4.74 × 10(4) copies/m(3)). Low temperatures and air pollution in winter negatively affected bacterial concentrations. Keystone taxa were identified by network analysis. Although about 50 % of the keystone taxa had low relative abundances, the strong impact of complex interactions between keystone taxa and other taxa on bacterial community structure deserved attention. The bacterial community assembly was dominated by stochastic processes (79.3 %). Interactions between bacteria and environmental filtering together affected bacterial community composition. Vertical gene transfer played an important role in the transmission of airborne ARGs. Given the potential integration and expression of ARGs in recipients, the human exposure risk due to high concentrations of ARGs and mobile genetic elements cannot be ignored. This study highlights human exposure to inhalable bacterial pathogens and ARGs in urban areas.202336584645
690240.9998Antibiotic resistance genes in surface water and groundwater from mining affected environments. Mining activities are known to generate a large amount of mine tailings and acid mine drainage which contain varieties of heavy metals. Heavy metals play an important role in co-selection for bacterial antibiotic resistance. However, the characteristics of antibiotic resistance genes (ARGs) in mining-affected water environments are still unclear. Here we investigated the pollution of metals, profiles of ARGs, mobile genetic elements (MGEs) and microbial community in mining-affected surface water and groundwater. The results showed that in the tested water samples, the concentrations of Zn and Mn were the highest, and Ni was the lowest. Higher abundances of ARGs with great proportion of sulfonamides, chloramphenicols and tetracyclines resistance genes were found in mining-affected water when compared with those without mining activities. Additionally, there were positive correlations between heavy metals (especially Ni, Zn and Mn) and these ARGs. Linear regression analysis suggested that MGEs were positively correlated with ARGs. In addition, total phosphorus was correlated with ARGs (p < 0.05). The microbial community was different between the mining-affected water and the reference (p < 0.05). Proteobacteria, Bacteroidetes and Actinobacteria were dominant phyla in the surface water and groundwater. Network analysis showed that many ARGs were significantly associated with these dominant bacteria, which suggested they might be potential hosts for these ARGs. These findings provide a clear evidence that the mining activities in the study area had a significant impact on surface water and groundwater to different degrees.202133571766
690350.9998Heavy Metal Tolerance Genes Associated With Contaminated Sediments From an E-Waste Recycling River in Southern China. Heavy metal pollution that results from electronic waste (e-waste) recycling activities has severe ecological environmental toxicity impacts on recycling areas. The distribution of heavy metals and the impact on the bacteria in these areas have received much attention. However, the diversity and composition of the microbial communities and the characteristics of heavy metal resistance genes (HMRGs) in the river sediments after long-term e-waste contamination still remain unclear. In this study, eight river sediment samples along a river in a recycling area were studied for the heavy metal concentration and the microbial community composition. The microbial community consisted of 13 phyla including Firmicutes (ranging from 10.45 to 36.63%), Proteobacteria (11.76 to 32.59%), Actinobacteria (14.81 to 27.45%), and unclassified bacteria. The abundance of Firmicutes increased along with the level of contaminants, while Actinobacteria decreased. A canonical correspondence analysis (CCA) showed that the concentration of mercury was significantly correlated with the microbial community and species distribution, which agreed with an analysis of the potential ecological risk index. Moreover, manually curated HMRGs were established, and the HMRG analysis results according to Illumina high-throughput sequencing showed that the abundance of HMRGs was positively related to the level of contamination, demonstrating a variety of resistance mechanisms to adapt, accommodate, and live under heavy metal-contaminated conditions. These findings increase the understanding of the changes in microbial communities in e-waste recycling areas and extend our knowledge of the HMRGs involved in the recovery of the ecological environment.202134054770
684860.9998Swine farming elevated the proliferation of Acinetobacter with the prevalence of antibiotic resistance genes in the groundwater. Swine farming generates a large amount of wastes containing various contaminants, resulting in environmental contamination and human health problems. Here we investigated the contamination profiles of antibiotics and antibiotic resistance genes (ARGs) as well as microbial community in groundwater of the two villages with or without swine farms, and then assessed the human exposure risks of antibiotics, ARGs and indicator bacteria through drinking groundwater. The results showed that swine farming could lead to enhanced concentration levels of various veterinary antibiotics and ARGs in the groundwater in comparison to the reference village without swine farming. The microbial diversity of groundwater was significantly decreased with predominance of conditional pathogens Acinetobacter (up to 90%) in some wells of the swine farming village. Meanwhile, the abundance of Acinetobacter was significantly correlated to bacterial abundance, ARGs and integrons. The local residents could ingest various antibiotic residues and ARGs as well as pathogens, with daily intake of Acinetobacter up to approximately 10 billion CFU/resident through drinking groundwater contaminated by swine farming. The findings from this study suggest potential health risks of changing gut microbial community and resistome by drinking contaminated groundwater.202031999967
681070.9998Heavy metals and microbiome are negligible drivers than mobile genetic elements in determining particle-attached and free-living resistomes in the Yellow River. Suspended particles in water can shelter both microorganisms and contaminants. However, the emerging pollutants antibiotic resistance genes (ARGs) in free-living (FL) or particle-attached (PA) bacteria in aquatic environments are less explored. In this study, we compared the free-living and particle-attached ARGs during four seasons in the Yellow River using high-throughput quantitative PCR techniques and 16S rRNA gene sequencing. Our results demonstrated that both the free-living water and particles were dominated by tetracycline and beta-lactamase resistance genes. The PA-ARGs had a higher absolute abundance than FL-ARGs in the Yellow River, regardless of the season. Both PA-ARGs and FL-ARGs had the highest absolute abundance and diversity during winter. Mobile genetic elements (MGEs) were the dominant driver for both size-fractionated ARGs. However, the microbiome had less influence on PA-ARG profiles than the FL-ARG profiles, while the effects of the heavy metals on ARGs were negligible. The community assembly of both FL-ARG and PA-ARG can be explained by neutral processes. Several opportunistic pathogens (e.g., Escherichia coli) associated with human health exhibited a higher relative abundance in the particles than during a free-living lifestyle. Parts of these pathogens were potential ARG hosts. As such, it is important to monitor the ARGs and opportunistic pathogens from size-fractionated bacteria and develop targeted strategies to manage ARG dissemination and opportunistic pathogens to ensure public health.202234736202
726580.9998Airborne bacterial communities and antibiotic resistance gene dynamics in PM(2.5) during rainfall. The biotoxicity and public health effects of airborne bacteria and antibiotic resistance genes (ARGs) in fine particulate matter (PM(2.5)) are being increasingly recognized. The characteristics of bacterial community composition and ARGs in PM(2.5) under different rainfall conditions were studied based on the on-site synchronous measurements in downtown Beijing. Marked differences were evident in the bacterial community characteristics of PM(2.5) before, during, and after rain events (p < 0.05). The rain intensities affected the bacterial community abundance in PM(2.5) and heavy rain had greater washing effects. The Proteobacteria (phylum level), α-Proteobacteria (class level), Pseudomonadales (order level), Pseudomonadaceae (family level), and Cyanobacteria (genus level) were the dominant bacterial taxa associated with PM(2.5) in Beijing during rain events. However, the bacteria at each level that displayed the biggest percentage variance was not the dominant type under different rain intensities. The ermB, tetW, and mphE genes were the primary ARGs, with abundances of 18 to 30 copies/m(3), which was a relatively smaller value than other observations. Real-time monitoring of the meteorological condition of rain events and physicochemical properties of PM(2.5) were used to identify the main factors during rainfall. The bacterial community was sensitive to the ionic and metal element components of PM(2.5) during rainfall. The abundance of ARGs was closely correlated with some groups of the bacterial community, which were also close to the initial value before the rain. Statistical analysis demonstrated that temperature, relative humidity, and duration of rain were the primary meteorological factors for the biological characteristics. The ionic species, rather than metal elements, in PM(2.5) were the sensitive factors for the bacteria community and ARGs, which varied at the phylum, class, order, family, and genus levels. The observations provide insights for the biological risk assessment in an urban rainfall water and the potential health impact on citizens.202031726367
321890.9998Airborne bacterial communities in the poultry farm and their relevance with environmental factors and antibiotic resistance genes. The accelerating occurrence and environmental dissemination of bacteria, gas pollutants and antibiotic resistance genes (ARGs) in aerosols of poultry farms have become emerging environmental issues due to their potential threat to animals, workers, and the communities located near such farms. Here, aerosol samples were gathered from inside and outside of the chicken house in winter with a transportable high-flow bioaerosol sampler. Then, 16S rRNA gene amplicon sequencing was used to categorize the bacteria in air samples, and the abundance of 12 ARG subtypes was researched via the real-time quantitative polymerase chain reaction (qPCR). Results indicated that the bacterial richness and diversity and total absolute abundance of ARGs were similar in the bioaerosols from indoor and downwind site of the poultry farm. The zoonotic pathogens, Staphylococcus and Corynebacterium, were detected both inside and outside of the chicken house, and the four most abundant target genes were bla(TEM), tetQ, ermB and sul1 in aerosols. Moreover, the correlation between the bacterial communities and environmental factors, such as NH(3) and H(2)S concentrations, wind speed, temperature and relative humidity, was analyzed. The result revealed that the indoor bacteria community was positively associated with temperature and concentrations of air pollutants (NH(3) and H(2)S), and could spread from confinement buildings to the ambient atmosphere through wind. In addition, the network analysis result showed that the airborne bacteria might significantly contribute in shaping the ARGs' profiles in bioaerosol from inside and outside of the poultry house. Overall, our results revealed the airborne bacterial communities and their associated influencing factors in the micro-environment (inside of the chicken house and nearby the boundary of the farm), and brought a new perspective for studying the gas pollutants and bioaerosol from poultry farms in winter.202235850323
6871100.9998Distinct profile of bacterial community and antibiotic resistance genes on microplastics in Ganjiang River at the watershed level. Microplastics are of great public concern due to their wide distribution and the potential risk to humans and animals. In this study, the microplastic pollution associated with bacterial communities, human pathogenic bacteria, and antibiotic resistance genes (ARGs) were investigated compared to water, sediment, and natural wood particles. Microplastics were widely distributed in surface water of the Ganjiang River at a watershed level with an average value of 407 particles m(-3). The fragment was the main microplastic shape found in the basin. Microplastics had significantly higher observed species and Chao1 index of bacterial communities than those in water, but comparable to wood particles. However, there was no difference in the microplastics pollution and alpha diversity indices of bacterial between different reaches along the Ganjiang River. Flavobacterium, Rhodoferax, Pseudomonas, and Janthinobacterium on the microplastics were all found to be enriched compared with water and sediment. Principal component analysis of the composition and function profile of bacterial communities showed that microplastics provide a new microbial niche in the Ganjiang River, which was distinct from water, sediment, and natural wood. Pseudomonas genus dominated the composition of human pathogenic bacteria on the microplastics, which was significantly different from water and sediment. No difference was observed in the relative abundance of total ARGs among the four media. However, microplastic and wood particles showed similar composition patterns of ARGs compared with water and sediment.202134048747
7046110.9998Contributions of meat waste decomposition to the abundance and diversity of pathogens and antibiotic-resistance genes in the atmosphere. Airborne transmission of antibiotic-resistance genes (ARGs) in landfill and acquisition of antibiotic resistance by pathogenic bacteria are posing potential threat to human and environmental health. However, little is known about contribution of waste decomposition to airborne ARGs and pathogens during landfilling of household waste. Herein, the dynamic changes of microbial communities and ARGs were comparatively investigated in leachate and bioaerosol during the decomposition of chicken, fish, and pork wastes. Results found that chicken and pork decomposition could result in emitting high abundance of bioaerosol and pathogen, while fish fermentation will lead to high airborne microbial activity. The main pathogens were Bacilli, Burkholderia-Paraburkholderia and Mycobacterium in bioaerosols, but were Wohlfahrtiimonas, Peptoniphilus and Fusobacterium in leachate, suggesting that the ability of aerosolization of bacteria in leachate was independent of their abundance and diversity. Whereas, diversity and relative abundance of ARGs in leachate were significantly higher than bioaerosol. Moreover, the relative abundance of ARGs in leachate and bioaerosols was not completely relevant. The changes of pathogenic community contributed significantly to the prevalence of ARGs in bioaerosol and leachate. The results will define the contribution of household waste decomposition to airborne pathogen and ARG distribution and provide foundation for airborne bacterial exposure risk and control in landfill.202134088047
6950120.9998Ceftiofur 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
7255130.9998Distribution of quinolone and macrolide resistance genes and their co-occurrence with heavy metal resistance genes in vegetable soils with long-term application of manure. The spread of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) has become an increasingly serious global public health issue. This study investigated the distribution characteristics and influencing factors of ARB and ARGs in greenhouse vegetable soils with long-term application of manure. Five typical ARGs, four heavy metal resistance genes (MRGs), and two mobile genetic elements (MGEs) were quantified by real-time quantitative polymerase chain reaction (qPCR). The amount of ARB in manure-improved soil greatly exceeded that in control soil, and the bacterial resistance rate decreased significantly with increases in antibiotic concentrations. In addition, the resistance rate of ARB to enrofloxacin (ENR) was lower than that of tylosin (TYL). Real-time qPCR results showed that long-term application of manure enhanced the relative abundance of ARGs in vegetable soils, and the content and proportion of quinolone resistance genes were higher than those of macrolide resistance genes. Redundancy analysis (RDA) showed that qepA and qnrS significantly correlated with total and available amounts of Cu and Zn, highlighting that certain heavy metals can influence persistence of ARGs. Integrase gene intI1 correlated significantly with the relative abundance of qepA, qnrS, and ermF, suggesting that intI1 played an important role in the horizontal transfer of ARGs. Furthermore, there was a weakly but not significantly positive correlation between specific detected MRGs and ARGs and MGEs. The results of this study enhance understanding the potential for increasing ARGs in manure-applied soil, assessing ecological risk and reducing the spread of ARGs.202234559332
6847140.9998Nutrients, heavy metals and microbial communities co-driven distribution of antibiotic resistance genes in adjacent environment of mariculture. With the rapid development of aquaculture, the large amounts of pollutants were discharged into the aquatic environment, where the detected antibiotic resistance genes (ARGs) have drawn increasing attention due to their potential threats to ecological environment and human health. Thus, the impact of mariculture on ARGs was assessed and the underlying mechanism of their propagation was explained. Sediments from eight sampling sites were collected along a mariculture drainage ditch, and the sediment in Yellow River Delta National Park was used as a non-mariculture control. Microbial ARGs qPCR array and illumina sequencing of 16S rRNA gene were applied to examine the changing patterns of ARGs and bacterial communities. Results showed that 18 ARGs (3 fluoroquinolone, 1 aminoglycoside, 3 macrolide-lincosamide-streptogramin B, 2 tetracycline, and 9 beta-lactam resistance genes) were influenced by mariculture, and ARGs abundance and diversity were significantly increased in mariculture sediments (p < 0.05). A remarkable shift in bacterial community structure and composition was also observed. The abundance of most of ARGs were significantly decreased in the estuary samples, implying that seawater had a significant dilution effect on the ARGs emission from the mariculture sites. Partial redundancy analysis showed that nutrients, heavy metals, and bacteria communities might directly and indirectly contribute to ARGs propagation, suggesting that the profile and dissemination of ARGs were driven by the combined effects of multiple factors in mariculture-impacted sites.201727814984
6886150.9998Bacterial community and antibiotic resistance genes assembly processes were shaped by different mechanisms in the deep-sea basins of the Western Pacific Ocean. As the intrinsic property of microorganisms, antibiotic resistance genes (ARGs) are fundamentally coupled to microbially-linked biogeochemical processes within ecosystems. However, human activities often obscure the natural distribution of ARGs through deterministic selective pressures. The deep-sea basin of the western Pacific Ocean is one of the least disturbed areas globally by human activities, providing a natural laboratory to investigate the intrinsic mechanisms governing ARGs in natural environments. In this study, we analyzed bacterial community and ARG diversity in 15 surface sediment samples from three deep-sea basins in the western Pacific Ocean. The relative abundance of ARGs in the surface sediments ranged from 3.10 × 10(-3) to 5.37 × 10(-2) copies/16S rRNA copies, with multidrug and β-lactam resistance genes dominated in all samples (49.06%-100%). The bacteria were mainly dominated by the Proteobacteria. The principal coordinate analysis (PCoA) showed significant spatial heterogeneity of ARGs and bacteria among the three basins. Null model, neutral community models (NCM), and normalized stochasticity ratio (NST) indicated that bacterial community was dominated by stochastic assembly, driven by geographic barriers leading to independent evolution. Conversely, the NST revealed that the ARGs profile was mainly shaped by deterministic processes. Environmental factors are more crucial than geographical factors and bacterial community for ARG occurrence among the selected factors. Meanwhile, we found that the spread of ARGs was mainly through vertical gene transfer in the pre-antibiotic era. The disparity between the assembly processes of bacterial community and ARGs may be attributed to the fact that ARG hosts were not the dominant bacteria in the community. This study first reported the distribution and assembly processes of ARGs and bacterial community in surface sediments of the western Pacific.202439481517
6850160.9998Fate of high-risk antibiotic resistance genes in large-scale aquaculture sediments: Geographical differentiation and corresponding drivers. Antibiotic resistance genes (ARGs), emerging environmental contaminants, have become challenges of public health security. However, the distribution and drivers of ARGs, especially high-risk ARGs, in large-scale aquaculture sediments remain unknown. Here, we collected sediment samples from 40 crayfish ponds in seven main crayfish culture provinces in China and then investigated the distribution and risk of ARGs based on high-throughput sequencing and quantitative PCR techniques. Our results suggested that aquaculture sediment was potential reservoir of ARGs and the abundance of aadA-02 was the highest. High-risk ARG (floR) was also prevalent in the sediment and was the most abundant in Jiangsu Province, where opportunistic pathogens were also enriched. The abundance of floR was positively correlated with different environmental factors, such as total phosphorus in water and total carbon in sediment. In addition, Mycobacterium sp., opportunistic pathogenic bacteria, might be potential host for floR. Furthermore, the potential propagation pathway of ARGs was from sediment to crayfish gut, and Bacteroidetes and Proteobacteria might be the main bacterial groups responsible for the proliferation of ARGs. Generally, our results illustrate that pond sediment may be an ARG reservoir of aquatic animals. Meanwhile, our study helps develop valuable strategies for accessing risks and managing ARGs.202337714353
7010170.9998Dynamics of metal(loid) resistance genes driven by succession of bacterial community during manure composting. Metal(loid) resistance genes (MRGs) play important roles in conferring resistance to metal(loid)s in bacterial communities. How MRGs respond to bacterial succession during manure composting remains largely unknown. Metagenomics was used in the present study to investigate the compositional changes of MRGs, their candidate hosts and association with integrons during thermophilic composting of chicken manures. MRGs conferring resistance to 20 metal(loid)s were detected, and their diversity and abundance (normalized to the abundance of 16S rRNA genes) were significantly reduced during composting. MRGs associated with integron were exclusively observed in proteobacterial species. Class 1 integron likely played an important role in maintaining mercury-resistance mer operon genes in composts. Escherichia coli harbored the most abundant MRGs in the original composting material, whereas species of Actinobacteria and Bacilli became more important in carrying MRGs during the late phases. There were significant linear relationships between the relative abundance of some specific bacterial species (E. coli, Actinobacteria species and Enterococcus faecium) and the abundance of MRGs they potentially harbored. The succession of these bacteria contributed to an overall linear regression between the relative abundance of all predicted candidate hosts and the abundance of total MRGs. Our results suggest that the succession of bacterial community was the main driver of MRG dynamics during thermophilic composting.201931563779
7155180.9998Profiles of antibiotic resistance genes in an inland salt-lake Ebinur Lake, Xinjiang, China: The relationship with antibiotics, environmental factors, and microbial communities. Lakes in arid northwestern China, as the main pollutant-holding water bodies in the typical ecologically fragile areas, are facing the unknown risk of exposure to antibiotics and antibiotic resistance genes (ARGs). In this study, five ARGs and one mobile genetic element (intI1) and their relation with antibiotics, microbial communities and water quality were investigated in Ebinur Lake Basin, a typical salt-lake of China. Quantitative PCR analysis indicated that ARGs decreasing order in both surface water and sediment was sul1 >sul2 >tetW>ermB>qnrS, which means sulfonamide resistance genes were the main pollution ARGs. Macrolide antibiotics were the predominant antibiotics in the surface water and sediment in winter, while sulfonamides and quinolones accounted for a high proportion in summer. There was a non-corresponding relationship between ARGs and antibiotics. Moreover, the relationship between ARGs and microbial communities were defined. Sulfonamide resistance genes were carried by a greater diversity of potential host bacteria (76 genera) than other ARGs (9 genera). And their positive correlation with intI1 (p < 0.05) which promotes their migration and provides possibility of their co-occurrence in bacterial populations (e.g., Nitrospira). Bacterial genera were the main driver of ARGs distribution pattern in highly saline lake sediment. Environmental factors like salinity, total nitrogen and organic matter could have a certain influence on the occurrence of ARGs by affecting microorganisms. The results systematically show the distribution and propagation characteristics of ARGs in typical inland salt-lakes in China, and preliminarily explored the relationship between ARGs and antibiotics, resistance genes and microorganisms in lakes in ecologically fragile areas.202134171688
8079190.9998Response of antibiotic resistance to the co-exposure of sulfamethoxazole and copper during swine manure composting. Heavy metals driven co-selection of antibiotic resistance in soil and water bodies has been widely concerned, but the response of antibiotic resistance to co-existence of antibiotics and heavy metals in composting system is still unknown. Commonly used sulfamethoxazole and copper were individually and jointly added into four reactors to explore their effects on antibiotic resistance genes (ARGs), mobile genetic elements (MGEs), heavy metal resistance genes (MRGs) and bacterial community structure. The abundance of total ARGs and MGEs were notably decreased by 68.64%-84.95% and 91.27-97.38%, respectively, after the composting. Individual addition of sulfamethoxazole, individual addition of copper, simultaneously addition of sulfamethoxazole and copper increased the abundance of ARGs and MGEs throughout the composting period. Co-exposure of sulfamethoxazole and copper elevated the total abundance of ARGs by 1.17-1.51 times by the end of the composting compared to individual addition of sulfamethoxazole or copper. Network analysis indicated that the shifts in potential host bacteria determined the ARGs variation. Additionally, MGEs and MRGs had significant effects on ARGs, revealing that horizontal gene transfer and heavy metals induced co-resistance could promote ARGs dissemination.202234537705