Shift in antibiotic resistance gene profiles associated with nanosilver during wastewater treatment. - Related Documents




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705601.0000Shift in antibiotic resistance gene profiles associated with nanosilver during wastewater treatment. This study investigated the response of antibiotic resistance genes (ARGs) to nanosilver (Ag) in lab-scale nitrifying sequencing batch reactors (SBRs), compared to Ag(+)-dosed and undosed controls. Quantitative polymerase chain reaction (q-PCR) targeting sul1, tet(O), ermB and the class I integron gene intI1 and corresponding RNA expression did not indicate measureable effects of nanoAg or Ag(+) on abundance or expression of these genes. However, high-throughput sequencing based metagenomic analysis provided a much broader profile of gene responses and revealed a greater abundance of aminoglycoside resistance genes (mainly strA) in reactors dosed with nanoAg. In contrast, bacitracin and macrolide-lincosamide-streptogramin (MLS) resistance genes were more abundant in the SBRs dosed with Ag(+). The distinct ARG profiles associated with nanoAg and Ag(+) were correlated with the taxonomic composition of the microbial communities. This study indicates that nanoAg may interact with bacteria differently from Ag(+) during biological wastewater treatment. Therefore, it cannot necessarily be assumed that nanosilver behaves identically as Ag(+) when conducting a risk assessment for release into the environment.201626850160
725610.9994Impact of direct application of biogas slurry and residue in fields: In situ analysis of antibiotic resistance genes from pig manure to fields. Biogas slurry and residue contaminated with antibiotics are widely used as fertilizers in vegetable crop planting. However, their impact on the spreading of antibiotic resistance genes (ARGs) in vegetable fields is still largely unknown. In the present study, antibiotic resistant bacteria (ARB), ARGs and bacterial communities from pig manure to fields were monitored by using viable plate counts, high-throughput fluorescent quantitative PCR (HT-qPCR) and Illumina MiSeq sequencing. Eighty-three ARGs and 3 transposons genes were detected. Anaerobic digestion reduced relative abundance of tetracycline and Macrolide-Lincosamide-Streptogramin (MLSB) resistance genes. However, the number of ARB and the relative abundance of sulfa, aminoglycoside and florfenicol, chloramphenicol, and amphenicol (FCA) resistance genes, respectively, enriched up to 270 times and 52 times in biogas residue. Long-term application of biogas slurry and residue contaminated with antibiotics in fields increased the rate of ARB as well as relative abundance of ARGs and transposons genes. Additionally, bacterial communities significantly differed between the soil treated with biogas slurry and residue and the control sample, especially the phyla Bacteroidetes and Actinobacteria. Based on network analysis, 19 genera were identified as possible hosts of the detected ARGs. Our results provide an important significance for reasonable application of biogas slurry and residue.201829096257
755220.9994Effect of temperature on removal of antibiotic resistance genes by anaerobic digestion of activated sludge revealed by metagenomic approach. As antibiotic resistance continues to spread globally, there is growing interest in the potential to limit the spread of antibiotic resistance genes (ARGs) from wastewater sources. In particular, operational conditions during sludge digestion may serve to discourage selection of resistant bacteria, reduce horizontal transfer of ARGs, and aid in hydrolysis of DNA. This study applied metagenomic analysis to examine the removal efficiency of ARGs through thermophilic and mesophilic anaerobic digestion using bench-scale reactors. Although the relative abundance of various ARGs shifted from influent to effluent sludge, there was no measureable change in the abundance of total ARGs or their diversity in either the thermophilic or mesophilic treatment. Among the 35 major ARG subtypes detected in feed sludge, substantial reductions (removal efficiency >90%) of 8 and 13 ARGs were achieved by thermophilic and mesophilic digestion, respectively. However, resistance genes of aadA, macB, and sul1 were enriched during the thermophilic anaerobic digestion, while resistance genes of erythromycin esterase type I, sul1, and tetM were enriched during the mesophilic anaerobic digestion. Efflux pump remained to be the major antibiotic resistance mechanism in sludge samples, but the portion of ARGs encoding resistance via target modification increased in the anaerobically digested sludge relative to the feed. Metagenomic analysis provided insight into the potential for anaerobic digestion to mitigate a broad array of ARGs.201525994259
726330.9994A comprehensive insight into tetracycline resistant bacteria and antibiotic resistance genes in activated sludge using next-generation sequencing. In order to comprehensively investigate tetracycline resistance in activated sludge of sewage treatment plants, 454 pyrosequencing and Illumina high-throughput sequencing were used to detect potential tetracycline resistant bacteria (TRB) and antibiotic resistance genes (ARGs) in sludge cultured with different concentrations of tetracycline. Pyrosequencing of 16S rRNA gene revealed that tetracycline treatment greatly affected the bacterial community structure of the sludge. Nine genera consisting of Sulfuritalea, Armatimonas, Prosthecobacter, Hyphomicrobium, Azonexus, Longilinea, Paracoccus, Novosphingobium and Rhodobacter were identified as potential TRB in the sludge. Results of qPCR, molecular cloning and metagenomic analysis consistently indicated that tetracycline treatment could increase both the abundance and diversity of the tet genes, but decreased the occurrence and diversity of non-tetracycline ARG, especially sulfonamide resistance gene sul2. Cluster analysis showed that tetracycline treatment at subinhibitory concentrations (5 mg/L) was found to pose greater effects on the bacterial community composition, which may be responsible for the variations of the ARGs abundance. This study indicated that joint use of 454 pyrosequencing and Illumina high-throughput sequencing can be effectively used to explore ARB and ARGs in the environment, and future studies should include an in-depth investigation of the relationship between microbial community, ARGs and antibiotics in sewage treatment plant (STP) sludge.201424905407
758640.9994Integrated metagenomic and metatranscriptomic analyses of ultraviolet disinfection effects on antibiotic resistance genes and bacterial communities during wastewater treatment. Ultraviolet (UV) disinfection is now widely implemented in wastewater treatment plants (WWTPs) worldwide, but its effect on antibiotic resistome of the surviving bacteria remains unclear. In this study, we employed high-throughput sequencing-based metagenomic and metatranscriptomic approaches to comprehensively elucidate the effects of UV disinfection on the shifts of bacterial community and antibiotic resistance genes (ARGs) on both DNA and mRNA levels in one WWTP. Metagenomic analyses revealed an insignificant change in the bacterial community after UV disinfection, while metatranscriptomic analyses showed that UV disinfection significantly changed the abundance of 13.79% of phyla and 10.32% of genera. In total, 38 ARG-like open reading frames (ORFs) and 327 ARG-like transcripts were identified in the DNA and RNA samples, respectively. The relative abundances of the total ARGs, each ARG type, and each ARG subtype also varied after UV disinfection. Additionally, UV disinfection significantly reduced the expression of total ARGs from 49.40 transcripts per kilobase of exon model per million mapped reads (TPM) to 47.62 TPM, and significantly changed the expression of 10.75% of ARG subtypes in wastewater (p < 0.05). Notably, the significant increase in the expression and obvious increase in the relative abundance of macrolide-lincosamide-streptogramin B (MLSB) resistance genes revealed that UV disinfection increases the potential health risk of MLSB resistance genes in wastewater. Moreover, potential host analyses of ARGs revealed the different preferences of antibiotic resistant bacteria (ARB) to ARGs. This study may shed new light on the underlying mechanism of the UV disinfection effect on antibiotic resistance.202133278015
725750.9994Housefly Larva Vermicomposting Efficiently Attenuates Antibiotic Resistance Genes in Swine Manure, with Concomitant Bacterial Population Changes. Manure from swine treated with antimicrobials as feed additives is a major source for the expansion of the antibiotic resistance gene (ARG) reservoir in the environment. Vermicomposting via housefly larvae (Musca domestica) can be efficiently used to treat manure and regenerate biofertilizer, but few studies have investigated its effect on ARG attenuation. Here, we tracked the abundances of 9 ARGs and the composition and structure of the bacterial communities in manure samples across 6 days of full-scale manure vermicomposting. On day 6, the abundances of genes encoding tetracycline resistance [tet(M), tet(O), tet(Q), and tet(W)] were reduced (P < 0.05), while those of genes encoding sulfonamide resistance (sul1 and sul2) were increased (P < 0.05) when normalized to 16S rRNA. The abundances of tetracycline resistance genes were correlated (P < 0.05) with the changing concentrations of tetracyclines in the manure. The overall diversity and richness of the bacteria significantly decreased during vermicomposting, accompanied by a 100 times increase in the relative abundance of Flavobacteriaceae spp. Variations in the abundances of ARGs were correlated with the changing microbial community structure and the relative abundances of the family Ruminococcaceae, class Bacilli, or phylum Proteobacteria. Vermicomposting, as a waste management practice, can reduce the overall abundance of ARGs. More research is warranted to assess the use of this waste management practice as a measure to attenuate the dissemination of antimicrobial residues and ARGs from livestock production before vermicompost can be safely used as biofertilizer in agroecosystems.201526296728
724360.9994Responses and successions of sulfonamides, tetracyclines and fluoroquinolones resistance genes and bacterial community during the short-term storage of biogas residue and organic manure under the incubator and natural conditions. Biogas residue and organic manure are frequently used for crop planting. However, the evaluation of antibiotic resistant bacteria (ARB), antibiotic resistance genes (ARGs) and bacterial community before their applications to fields is still lacking. This study monitored the variations of bacteria resistant to sulfadiazine, tetracycline and norfloxacin, 57 resistance genes for sulfonamides, tetracyclines and fluoroquinolones as well as the bacterial community during the 28-day aerobic storage of biogas residue and organic manure by using viable plate counts, high-throughput qPCR and Illumina MiSeq sequencing methods. Then two storage conditions, incubator (25 °C) and natural environment, were used to assess the responses of ARB and ARGs to the environmental factors. Results showed that a total of 35 and 21 ARGs were detected in biogas residue and organic manure, respectively. ARB and ARGs were enriched up to 8.01-fold in biogas residue after the 28-day storage, but varied in a narrow range during the storage of organic manure. Compared with the incubator condition, the proliferation of ARB and ARGs in biogas residue under the natural condition was relatively inhibited by the varied and complicated environmental factors. However, we found that there was no significant difference of ARB and ARGs in organic manure between the incubator and natural conditions. Bacterial community was also shifted during the storage of biogas residue, especially Bacteroidetes_VC2.1_Bac22, Aequorivita, Luteimonas and Arenimonas. Network analysis revealed that the relationship in biogas residue was much more complicated than that in organic manure, which ultimately resulted in large successions of ARB and ARGs during the short-term storage of biogas residue. Therefore, we suggest that further measures should be taken before the application of biogas residue to fields.201830031308
694870.9994Fate of antibiotic resistance genes and metal resistance genes during the thermophilic fermentation of solid and liquid swine manures in an ectopic fermentation system. Environmental pollution due to resistance genes from livestock manure has become a serious issue that needs to be resolved. However, little studies focused on the removal of resistance genes in simultaneous processing of livestock feces and urine. This study investigated the fate of antibiotic resistance genes (ARGs), metal resistance genes (MRGs), and class 1 integron-integrase gene (intI1) during thermophilic fermentation of swine manure in an ectopic fermentation system (EFS), which has been regarded as a novel system for efficiently treating both feces and urine. The abundances of MRGs and tetracycline resistance genes were 34.44-97.71% lower in the EFS. The supplementation of heavy metals significantly increased the abundance of intI1, with the enhancement effect of copper being more prominent than that of zinc. The highest abundances of resistance genes and intI1 were observed at high Cu levels (A2), indicating that Cu can increase the spreading of resistance genes through integrons. Network analysis revealed the co-occurrence of ARGs, MRGs, and intI1, and these genes potentially shared the same host bacteria. Redundancy analysis showed that the bacterial community explained most of the variations in ARGs, and environmental factors had influences on ARGs abundances by modulating the bacterial community composition. The decreased Sphingomonas, Comamonas, Acinetobacter, Lactobacillus, Bartonella, Rhizobium, and Bacteroides were mainly responsible for the reduced resistance genes. These results demonstrate that EFS can reduce resistance genes in simultaneous processing of livestock feces and urine.202133592372
701080.9994Dynamics 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
701490.9994Correlations among Antibiotic Resistance Genes, Mobile Genetic Elements and Microbial Communities in Municipal Sewage Treatment Plants Revealed by High-Throughput Sequencing. Municipal sewage treatment plants (MSTPs) are environmental pools for antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs), which is cause for growing environmental-health concerns. In this study, the effects of different wastewater treatment processes on microbial antibiotic resistance in four MSTPs were investigated. PCR, q-PCR, and molecular cloning integrally indicated that the tetracycline resistance (tet) genes significantly reduced after activated-sludge treatment. Illumina high-throughput sequencing revealed that the broad-spectrum profile of ARGs and mobile element genes (MGEs) were also greatly decreased by one order of magnitude via activated sludge treatment and were closely associated with each other. Correlations between ARGs and bacterial communities showed that potential ARB, such as Acinetobacter, Bacteroides, and Cloaibacterium, were removed by the activated-sludge process. Sedimentation processes cannot significantly affect the bacterial structure, resulting in the relative abundance of ARGs, MGEs, and ARB in second-clarifier effluent water being similar to activated sludge. A comprehensive study of ARGs associated with MGEs and bacterial structure might be technologically guided for activated sludge design and operation in the MSTPs, to purposefully control ARGs carried by pathogenic hosts and mobility.202336834289
6950100.9994Ceftiofur 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
7066110.9994Seasonality of antibiotic prescriptions for outpatients and resistance genes in sewers and wastewater treatment plant outflow. To test the hypothesis of a seasonal relationship of antibiotic prescriptions for outpatients and the abundance of antibiotic resistance genes (ARGs) in the wastewater, we investigated the distribution of prescriptions and different ARGs in the Dresden sewer system and wastewater treatment plant during a two-year sampling campaign. Based on quantitative PCR (qPCR), our results show a clear seasonal pattern for relative ARGs abundances. The higher ARGs levels in autumn and winter coincide with the higher rates of overall antibiotic prescriptions. While no significant differences of relative abundances were observed before and after the wastewater treatment for most of the relative ARGs, the treatment clearly influenced the microbial community composition and abundance. This indicates that the ARGs are probably not part of the dominant bacterial taxa, which are mainly influenced by the wastewater treatment processes, or that plasmid carrying bacteria remain constant, while plasmid free bacteria decrease. An exception was vancomycin (vanA), showing higher relative abundance in treated wastewater. It is likely that a positive selection or community changes during wastewater treatment lead to an enrichment of vanA. Our results demonstrate that in a medium-term study the combination of qPCR and next generation sequencing corroborated by drug-related health data is a suitable approach to characterize seasonal changes of ARGs in wastewater and treated wastewater.201627073234
6999120.9994Different 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
7069130.9994Native soil microorganisms hinder the soil enrichment with antibiotic resistance genes following manure applications. Bacterial genes responsible for resistance to antibiotic agents (ARG) are spread from livestock to soil through application of manure, threatening environmental and human health. We investigated the mechanisms of ARG dissemination and persistence to disentangle i) the influence of nutrients and microorganisms on the soil tetracycline (TET) resistome, and ii) the role of indigenous soil microbiota in preventing ARG spread. We analysed short-term (7 days) and persistent (84 days) effects of manure on the resistome of three antibiotic-free pasture soils. Four microcosm treatments were evaluated: control, mineral nutrient fertilization, and deposition of a layer of fresh manure onto soil or γ-irradiated soil. We quantified five TET-resistance genes, isolated 135 TET-resistant bacteria and sequenced both culturable TET-resistant and whole bacterial communities. Manure amendments, but not nutrient addition, increased the abundance of TET-r genes such as tet(Y). Such changes persisted with time, in contrast with the TET-resistant bacterial composition, which partially recovered after manure amendments. Manured γ-irradiated soils showed significantly lower nutrient content and higher TET-r gene abundance than non-irradiated soils, suggesting that native soil bacteria are essential for the fertilization effect of manure on soil as well as control the dissemination of potentially risky TET-r genes.201931043618
6954140.9994Temporal 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
7015150.9994Comparison of bacterial communities and antibiotic resistance genes in oxidation ditches and membrane bioreactors. Oxidation ditches (ODs) and membrane bioreactors (MBRs) are widely used in wastewater treatment plants (WWTPs) with bacteria and antibiotic resistance genes (ARGs) running through the whole system. In this study, metagenomic sequencing was used to compare the bacterial communities and ARGs in the OD and MBR systems, which received the same influent in a WWTP located in Xinjiang, China. The results showed that the removal efficiency of pollutants by the MBR process was better than that by the OD process. The composition and the relative abundance of bacteria in activated sludge were similar at the phylum and genus levels and were not affected by process type. Multidrug, fluoroquinolones and peptides were the main ARG types for the two processes, with macB being the main ARG subtype, and the relative abundance of ARG subtypes in MBR effluent was much higher than that in the OD effluent. The mobile genetic elements (MGEs) in the activated sludge were mainly transposons (tnpA) and insertion sequences (ISs; IS91). These results provide a theoretical basis for process selection and controlling the spread of ARGs.202133903636
8091160.9994Changes in antibiotic resistance genes and mobile genetic elements during cattle manure composting after inoculation with Bacillus subtilis. This study explored the effects of Bacillus subtilis at four levels (0, 0.5%, 1%, and 2% w/w compost) on the variations in ARGs, mobile genetic elements (MGEs), and the bacterial community during composting. The composting process had a greater impact on ARGs than Bacillus subtilis. The main ARG detected was sul1. The addition of Bacillus subtilis at 0.5% reduced the relative abundances of ARGs, MGEs, and human pathogenic bacteria (by 2-3 logs) in the mature products. Network and redundancy analyses suggested that intI1, Firmicutes, and pH were mainly responsible for the changes in ARGs, thus controlling these factors might help to inhibit the spread of ARGs.201931442833
6947170.9994Co-occurrence of genes for antibiotic resistance and arsenic biotransformation in paddy soils. Paddy soils are potential hotspots of combined contamination with arsenic (As) and antibiotics, which may induce co-selection of antibiotic resistance genes (ARGs) and As biotransformation genes (ABGs), resulting in dissemination of antimicrobial resistance and modification in As biogeochemical cycling. So far, little information is available for these co-selection processes and specific patterns between ABGs and ARGs in paddy soils. Here, the 16S rRNA amplicon sequencing and high-throughput quantitative PCR and network analysis were employed to investigate the dynamic response of ABGs and ARGs to As stress and manure application. The results showed that As stress increased the abundance of ARGs and mobile genetic elements (MGEs), resulting in dissemination risk of antimicrobial resistance. Manure amendment increased the abundance of ABGs, enhanced As mobilization and methylation in paddy soil, posing risk to food safety. The frequency of the co-occurrence between ABGs and ARGs, the host bacteria carrying both ARGs and ABGs were increased by As or manure treatment, and remarkably boosted in soils amended with both As and manure. Multidrug resistance genes were found to have the preference to be co-selected with ABGs, which was one of the dominant co-occurring ARGs in all treatments, and manure amendment increased the frequency of Macrolide-Lincosamide-Streptogramin B resistance (MLSB) to co-occur with ABGs. Bacillus and Clostridium of Firmicutes are the dominant host bacteria carrying both ABGs and ARGs in paddy soils. This study would extend our understanding on the co-selection between genes for antibiotics and metals, also unveil the hidden environmental effects of combined pollution.202336375951
7255180.9994Distribution 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
7067190.9994Impact of the antibiotic doxycycline on the D. magna reproduction, associated microbiome and antibiotic resistance genes in treated wastewater conditions. Wastewater Treatment Plant (WWTP) effluents are important sources of antibiotics, antibiotic resistance genes (ARGs) and resistant bacteria that threaten aquatic biota and human heath. Antibiotic effects on host-associated microbiomes, spread of ARGs and the consequences for host health are still poorly described. This study investigated changes of the Daphnia magna associated microbiome exposed to the recalcitrant antibiotic doxycycline under artificial reconstituted lab water media (lab water) and treated wastewater media. D. magna individual juveniles were exposed for 10 days to treated wastewater with and without doxycycline, and similarly in lab water. We analysed 16 S rRNA gene sequences to assess changes in community structure, monitored Daphnia offspring production and quantified ARGs abundances by qPCR from both Daphnia and water (before and after the exposure). Results showed that doxycycline and media (lab water or wastewater) had a significant effect modulating Daphnia-associated microbiome composition and one of the most discriminant taxa was Enterococcus spp. Moreover, in lab water, doxycycline reduced the presence of Limnohabitans sp., which are dominant bacteria of the D. magna-associated microbiome and impaired Daphnia reproduction. Contrarily, treated wastewater increased diversity and richness of Daphnia-associated microbiome and promoted fecundity. In addition, the detected ARG genes in both lab water and treated wastewater medium included the qnrS1, sul1, and bla(TEM,) and the integron-related intI1 gene. The treated wastewater contained about 10 times more ARGs than lab water alone. Furthermore, there was an increase of sul1 in Daphnia cultured in treated wastewater compared to lab water. In addition, there were signs of a higher biodegradation of doxycycline by microbiomes of treated wastewater in comparison to lab water. Thus, results suggest that Daphnia-associated microbiomes are influenced by their environment, and that bacterial communities present in treated wastewater are better suited to cope with the effects of antibiotics.202337442322