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705500.9911Characterization of antibiotic resistance genes and bacterial community in selected municipal and industrial sewage treatment plants beside Poyang Lake. Sewage treatment plants (STPs) are significant reservoirs of antibiotic resistance genes (ARGs) and antibiotic-resistant bacteria (ARB). Municipal STPs (MSTPs) and industrial STPs (ISTPs) are the two most important STP types in cities. In this study, the ARGs, mobile genetic elements (MGEs), and bacterial communities of selected STPs, including two MSTPs and one ISTP, in the vicinity of Poyang Lake were comprehensively investigated through high-throughput qPCR and high-throughput Illumina sequencing. The results showed that the profiles of ARGs, MGEs and bacteria differed between the ISTP and the two MSTPs, most likely due to differences in influent water quality, such as the Pb that characterized in the ISTP's influent. The longer hydraulic retention times (HRTs) of the two MSTPs than of the ISTP may also have accounted for the different profiles. Thus, a prolonged HRT in the CASS process seems to allow a more extensive removal of ARGs and bacteria in ISTPs with similar treatment process. By providing comprehensive insights into the characteristics of ARGs, MGEs and the bacterial communities of the selected MSTPs and ISTP, our study provides a scientific basis for controlling the propagation and diffusion of ARGs and ARB in different types of STPs.202032092547
735810.9909Global dispersal and potential sources of antibiotic resistance genes in atmospheric remote depositions. Antibiotic resistance has become a major Global Health concern and a better understanding on the global spread mechanisms of antibiotic resistant bacteria (ARB) and intercontinental ARB exchange is needed. We measured atmospheric depositions of antibiotic resistance genes (ARGs) by quantitative (q)PCR in rain/snow collected fortnightly along 4 y. at a remote high mountain LTER (Long-Term Ecological Research) site located above the atmospheric boundary layer (free troposphere). Bacterial composition was characterized by 16S rRNA gene sequencing, and air mass provenances were determined by modelled back trajectories and rain/snow chemical composition. We hypothesize that the free troposphere may act as permanent reservoir and vector for ARB and ARGs global dispersal. We aimed to i) determine whether ARGs are long-range intercontinental and persistently dispersed through aerosols, ii) assess ARGs long-term atmospheric deposition dynamics in a remote high mountain area, and iii) unveil potential diffuse ARGs pollution sources. We showed that the ARGs sul1 (resistance to sulfonamides), tetO (resistance to tetracyclines), and intI1 (a proxy for horizontal gene transfer and anthropogenic pollution) were long-range and persistently dispersed in free troposphere aerosols. Major depositions of tetracyclines resistance matched with intensification of African dust outbreaks. Potential ARB mostly traced their origin back into agricultural soils. Our study unveils that air masses pathways are shaping ARGs intercontinental dispersal and global spread of antibiotic resistances, with potential predictability for interannual variability and remote deposition rates. Because climate regulates aerosolization and long-range air masses movement patterns, we call for a more careful evaluation of the connections between land use, climate change and ARB long-range intercontinental dispersal.202235016024
350020.9909Shifts in bacterial communities and antibiotic resistance genes in surface water and gut microbiota of guppies (Poecilia reticulata) in the upper Rio Uberabinha, Brazil. Anthropogenic activities especially water pollution can affect the diversity and composition of microbial communities and promote the spread of antibiotic resistance genes (ARGs). In this study, water samples and guppies (Poecilia reticulata) were sampled from six sampling sites along the Uberabinha River in southeastern Brazil, both microbial communities and ARGs of surface waters and intestinal microbiota of guppies (Poecilia reticulata) were detected. According to the results of 16S rRNA amplicon sequencing, Proteobacteria, Bacteroidetes, Firmicutes and Actinobacteria were dominant phyla in both water and intestinal microbiota, but the abundance of putative pathogens was higher at heavily polluted sites. Up to 83% of bacteria in intestinal microbiota originated from water microbiota; this proportion was relatively higher in less polluted compared to polluted environments. ARGs providing resistance of tetracyclines and quinolones were dominant in both water and gut microbiota. The relative abundances of class I integrons and ARGs were as high as 1.74 × 10(-1)/16S rRNA copies and 3.61 × 10(-1)/16S rRNA copies, respectively, at heavily polluted sites. Correlation analysis suggests that integrons and bacteria play key roles in explaining the widespread occurrence of ARGs in the surface, but not in intestinal microbiota. We could rule out the class I integrons a potential intermediary bridge for ARGs between both types of microbiomes. Our results highlight the tight link in microbial communities and ARGs between ambient microbiota of stream ecosystems and intestinal microbiota of fish. Our study could have far-reaching consequences for fisheries and consumer safety and calls for investigations of gut microbiota of target species of both commercial fisheries and recreational (hobby) angling.202133497859
727630.9909Antibiotic resistance in urban and hospital wastewaters and their impact on a receiving freshwater ecosystem. The main objective of this study was to investigate the antibiotic resistance (AR) levels in wastewater (WW) and the impact on the receiving river. Samples were collected once per season over one year in the WW of a hospital, in the raw and treated WW of two wastewater treatment plants (WWTPs), as well as upstream and downstream from the release of WWTPs effluents into the Zenne River (Belgium). Culture-dependent methods were used to quantify Escherichia coli and heterotrophic bacteria resistant to amoxicillin, sulfamethoxazole, nalidixic acid and tetracycline. Six antibiotic resistance genes (ARGs) were quantified in both particle-attached (PAB) and free-living (FLB) bacteria. Our results showed that WWTPs efficiently removed antibiotic resistant bacteria (ARB) regardless of its AR profile. The ARGs levels were the highest in the hospital WW and were significantly reduced in both WWTPs. However, ARB and ARGs abundances significantly increased into the Zenne River downstream from the WWTPs outfalls. The variation in the relative abundance of ARGs through WW treatment differed depending on the WWTP, fraction, and gene considered. The sul1 and sul2 genes in PAB fraction showed significantly higher relative abundances in the effluent compared to the influent of both WWTPs. This study demonstrated that WWTPs could be hotspots for AR spread with significant impacts on receiving freshwater ecosystems. This was the first comprehensive study investigating at the same time antibiotics occurrence, fecal bacteria indicators, heterotrophic bacterial communities, and ARGs (distinguishing PAB and FLB) to assess AR levels in WW and impacts on the receiving river.201829730567
721540.9908High-throughput qPCR profiling of antimicrobial resistance genes and bacterial loads in wastewater and receiving environments. Wastewater treatment plants (WWTPs) are hot spots for the acquisition and spread of antimicrobial resistance (AMR). This regional-based study quantified antibiotic resistance genes (ARGs), mobile genetic elements (MGEs), and bacteria in hospital and community-derived wastewater and receiving environments, using high-throughput qPCR (HT-qPCR). This is the first study to apply Resistomap's Antibiotic Resistance Gene Index (ARGI) as a standardised metric to find the overall AMR level across different WWTPs. ARGI of WWTPs ranged from 2.0 to 2.3, indicating higher relative ARG levels than the mean European ARGI of 2.0, but lower than the global mean of 2.4. The highest diversity and abundance of ARGs were observed in untreated hospital and community wastewater. The reduction of total ARGs during wastewater treatment (0.2-2 logs) and bacteria (0.3-1.5 logs) varied spatio-temporally across the WWTPs. Despite a decrease in ARG and bacterial abundance in treated effluents, substantial loads were still released into receiving environments. Notably, ARG levels in coastal sediments were comparable to those in untreated wastewater, and most ARGs were shared between wastewater and receiving environments, highlighting the impact of wastewater discharge on these ecosystems. Sewage outfall exposure increased ARGs in shellfish, emphasising risks to shellfish hygiene. This study provides evidence to inform policymaking, emphasising advanced wastewater treatment methods and combined sewer overflow (CSO) management to mitigate ARG release, protecting water users and the food chain.202540127809
721650.9908Tracking antibiotic resistance through the environment near a biosolid spreading ground: Resistome changes, distribution, and metal(loid) co-selection. The application of urban wastewater treatment plants (WWTPs) products to agricultural lands has contributed to the rising level of antibiotic resistance and drawn a critical public health concern. It has not been thoroughly investigated at which spatial scales a biosolid applied area as a potentially predominant source affects surrounding soil resistomes. This study investigated distribution and impact of WWTP biosolids treated with anaerobic digestion on an agricultural area. Heterotrophic plate counts (HPCs) and quantitative polymerase chain reaction (qPCR) were performed for detection of selected antibiotic-resistant bacteria (ARB), selected antibiotic resistance genes (ARGs), intI1 genes, and 16S rRNA genes. Biosolid samples contained significantly higher levels of selected ARGs than the raw agricultural soils (p < 0.05). The average relative abundances of intI1, sul1, bla(SHV), and ermB genes were significantly higher in biosolid-amended soils than nearby agricultural soils (p < 0.05). Spatial interpolation analysis of relative gene abundances of intI1, sul1, sul2, and tetW across the studied area further indicated directional trends towards the northwest and southeast directions, highlighting possible airborne spread. Concentrations of Co, Cu, Ni, and Fe were found to be significantly and positively correlated with relative abundances of intI1, sul1, and tetW genes (p < 0.05). The resistance ratios of culturable antibiotic-resistant bacteria in agricultural soils with biosolid amendments were generally identical to those without biosolid amendments. This study will advance the understanding of the antibiotic resistome in agricultural soils impacted by long-term waste reuse and inform the evaluation strategies for future biosolids application and management.202235121038
349860.9907Comparative study on the bacterial diversity and antibiotic resistance genes of urban landscape waters replenished by reclaimed water and surface water in Xi'an, China. Pathogenic bacteria and antibiotic resistance genes (ARGs) in urban landscape waters may pose a potential threat to human health. However, the investigation of their occurrence in the urban landscape waters replenished by reclaimed water (RW) and surface water (SW) is still insufficient. The water samples collected from six urban landscape waters replenished by RW or SW were used to analyze bacterial diversity using high-throughput sequencing of 16S rRNA gene and to detect 18 ARGs and 2 integron-integrase genes by means of quantitative PCR array. Results indicated that Proteobacteria was the dominant phylum in all six urban landscape waters. The bacterial species richness was lower in urban landscape waters replenished by RW than that by SW. Sulfonamide resistance genes (sulI and sulIII) were the major ARGs in these urban landscape waters. No significant difference in the relative abundance of sulfonamide resistance genes, tetracycline resistance genes, and most of beta-lactam resistance genes was observed between RW-replenished and SW-replenished urban landscape waters. By contrast, the relative abundance of bla(ampC) gene and qnrA gene in RW-replenished urban landscape waters was significantly higher than that in SW-replenished urban landscape waters (p < 0.05), which suggested that use of RW may increase the amount of specific ARGs to urban landscape waters. Interestingly, among six urban landscape waters, RW-replenished urban landscape waters had a relatively rich variety of ARGs (12-15 of 18 ARGs) but a low relative abundance of ARGs (458.90-1944.67 copies/16S × 10(6)). The RW replenishment was found to have a certain impact on the bacterial diversity and prevalence of ARGs in urban landscape waters, which provide new insight into the effect of RW replenishment on urban landscape waters.202133786766
679070.9907Overlooked dissemination risks of antimicrobial resistance through green tide proliferation. Green tides, particularly those induced by Enteromorpha, pose significant environmental challenges, exacerbated by climate change, coastal eutrophication, and other anthropogenic impacts. More concerningly, these blooms may influence the spread of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) within ecosystems. However, the manner in which Enteromorpha blooms affect the distribution and spread of antimicrobial resistance (AMR) remains uncertain. This study investigated ARG profiles, dynamic composition, and associated health risks within the Enteromorpha phycosphere and surrounding seawater in typical bays (Jiaozhou, Aoshan, and Lingshan) in the South Yellow Sea. The Enteromorpha phycosphere exhibited significantly higher ARG abundance (p < 0.05) but lower diversity compared to the surrounding seawater. Source-tracking and metagenomic analyses revealed that the phycosphere was the main contributor to the resistome of surrounding seawater. Moreover, resistant pathogens, especially ESKAPE pathogens, with horizontal gene transfer (HGT) potential, were more abundant in the phycosphere than in the surrounding seawater. The phycosphere released high-risk ARGs to the surrounding seawater during Enteromorpha blooms, posing serious health and ecological AMR risks in marine environments. This study highlights the significant role of Enteromorpha blooms in ARG spread and associated risks, urging a reassessment of AMR burden from a public health perspective.202539488061
713480.9907Elevated levels of antibiotic resistance in groundwater during treated wastewater irrigation associated with infiltration and accumulation of antibiotic residues. Treated wastewater irrigation (TWW) releases antibiotics and antibiotic resistance genes (ARGs) into the environment and might thus promote the dissemination of antibiotic resistance in groundwater (GW). We hypothesized that TWW irrigation increases ARG abundance in GW through two potential mechanisms: the contamination of GW with resistant bacteria and the accumulation of antibiotics in GW. To test this, the GW below a real-scale TWW-irrigated field was sampled for six months. Sampling took place before, during and after high-intensity TWW irrigation. Samples were analysed with 16S rRNA amplicon sequencing, qPCR of six ARGs and the class 1 integron-integrase gene intI1, while liquid chromatography tandem mass spectrometry was performed to detect antibiotic and pharmaceutical residues. Absolute abundance of 16S rRNA in GW decreased rather than increased during long-term irrigation. Also, the relative abundance of TWW-related bacteria did not increase in GW during long-term irrigation. In contrast, long-term TWW irrigation increased the relative abundance of sul1 and intI1 in the GW microbiome. Furthermore, GW contained elevated concentrations of sulfonamide antibiotics, especially sulfamethoxazole, to which sul1 confers resistance. Total sulfonamide concentrations in GW correlated with sul1 relative abundance. Consequently, TWW irrigation promoted sul1 and intI1 dissemination in the GW microbiome, most likely due to the accumulation of drug residues.202234555761
699190.9906Distribution and drivers of antibiotic resistance genes in brackish water aquaculture sediment. Brackish water aquaculture has brought numerous economic benefits, whereas anthropogenic activities in aquaculture may cause the dissemination of antibiotic resistance genes (ARGs) in brackish water sediments. The intricate relationships between environmental factors and microbial communities as well as their role in ARGs dissemination in brackish water aquaculture remain unclear. This study applied PCR and 16S sequencing to identify the variations in ARGs, class 1 integron gene (intI1) and microbial communities in brackish water aquaculture sediment. The distribution of ARGs in brackish water aquaculture sediment was similar to that in freshwater aquaculture, and the sulfonamide resistance gene sul1 was the indicator of ARGs. Proteobacteria and Firmicutes were the dominant phyla, and Paenisporosarcina (p_ Firmicutes) was the dominant genus. The results of correlation, network and redundancy analysis indicated that the microbial community in the brackish water aquaculture sediment was function-driven. The neutral model and variation partitioning analysis were used to verify the ecological processes of the bacterial community. The normalized stochasticity ratio showed that pond bacteria community was dominated by determinacy, which was affected by aquaculture activities. The total nitrogen and organic matter influenced the abundance of ARGs, while Proteobacteria and Thiobacillus (p_Proteobacteria) were the key antibiotic-resistant hosts. Our study provides insight into the prevalence of ARGs in brackish water aquaculture sediments, and indicates that brackish water aquaculture is a reservoir of ARGs.202336436623
6957100.9906Untreated swine wastes changed antibiotic resistance and microbial community in the soils and impacted abundances of antibiotic resistance genes in the vegetables. Animal waste fertilization is a traditional agricultural practice, which may have adverse effects to soil ecosystem. However, the side-effects of animal waste fertilization on vegetables are less studied. Here we selected a swine farming village for investigation with a nearby village without swine farming as comparison. In the swine farming village, the farmers use untreated swine manure and wastewater as fertilizers for vegetable cultivation. In the reference village, the farmers mainly use commercial organic fertilizers. The objective of this study is to assess the impacts of untreated swine waste fertilization on both soils and vegetables in terms of antibiotics, antibiotic resistance genes (ARGs) and bacterial microbial communities. The results indicate that untreated swine waste fertilization caused both antibiotic and ARG contaminations and changed the microbial community compositions in the soils. Varieties of tetracyclines and related resistance genes were detected especially in swine wastewater treated soils. The soil quality was impacted with the relations to bacterial abundances and microbial geochemical functions. Proteobacteria and Bacteroidetes were prevalent and positively correlated to ARGs in soils, indicating they were potential antibiotic resistant bacteria. Antibiotics and ARGs were detected in vegetables of both villages. The abundances of ARGs were relatively higher in some vegetable samples of the swine farming village than the reference village. In addition, intracellular parasites Rickettsiales with positive correlation to ARGs were prevalent in some vegetables of swine farming village, indicating potential health risks through eating contaminated vegetables. The results of this study suggest that untreated swine wastes may cause adverse effects to not only agricultural soils but also associated vegetables.202032615438
7327110.9906Exploring the microbiome, antibiotic resistance genes, mobile genetic element, and potential resistant pathogens in municipal wastewater treatment plants in Brazil. Wastewater treatment plants (WWTPs) have been widely investigated in Europe, Asia and North America regarding the occurrence and fate of antibiotic resistance (AR) elements, such as antibiotic resistance genes (ARGs), mobile genetic elements (MGEs) and antibiotic resistant bacteria and pathogens. However, monitoring data about AR elements in municipal WWTPs in Brazil are scarce. This study investigated the abundance of intI1, five ARGs (sul1, tetA, blaTEM, ermB and qnrB) and 16S rRNA in raw and treated wastewater of three WWTPs, using different sewage treatments named CAS (Conventional activated sludge), UASB/BTF (UASB followed by biological trickling filter) and MAS/UV (modified activated sludge with UV disinfection stage). Bacterial diversity and the presence of potentially pathogenic groups were also evaluated, and associations between genetic markers and the bacterial populations were presented. All WWTPs decreased the loads of genetic markers finally discharged to receiving water bodies and showed no evidence of being hotspots for antimicrobial resistance amplification in wastewater, since the abundances of intI1 and ARGs within the bacterial population were not increased in the treated effluents. UASB/BTF showed a similar performance to that of the CAS and MAS/UV, reinforcing the sanitary and environmental advantages of this biological treatment, widely applied for wastewater treatment in warm climate regions. Bacterial diversity and richness increased after treatments, and bacterial communities in wastewater samples differed due to catchment areas and treatment typologies. Potential pathogenic population underwent considerable decrease after the treatments; however, strong significant correlations with intI1 and ARGs revealed potential multidrug-resistant pathogenic bacteria (Aeromonas, Arcobacter, Enterobacter, Escherichia-Shigella, Stenotrophomonas and Streptococcus) in the treated effluents, although in reduced relative abundances. These are contributive results for understanding the fate of ARGs, MGEs and potential pathogenic bacteria after wastewater treatments, which might support actions to mitigate their release into Brazilian aquatic environments in the near future.202235724791
3502120.9906Microbial dynamics in a swine wastewater treatment plant and prediction of potential hosts of antibiotic resistance genes. Using a culture-independent approach, this study aimed to evaluate microbial community changes in a swine wastewater treatment plant (SWWTP) and investigate the presence of bacteria for public health concerns, particularly those harboring antibiotic resistance genes (ARG) with pathogenic potential. Through sequencing of fifteen samples collected across five sampling campaigns - at the influent, biodigester outlet, and final effluent - higher microbial diversity was observed in the untreated waste, reflected by a greater relative abundance of operational taxonomic units (OTUs) linked to the families Streptococcaceae (up to 27 %), unidentified members of the order Clostridiales (up to 33 %), and Moraxellaceae (up to 19 %). A microbial succession was observed across subsequent treatment stages, characterized by an increased relative abundance of OTUs associated with Clostridiaceae (0-68 %) and Peptostreptococcaceae (8-25 %), likely driven by environmental conditions. Sequences related to the order Clostridiales and the family Moraxellaceae showed correlations with the resistance genes blaTEM, ermB, qnrB, sul1, and tetA, suggesting that members of these groups could serve as potential gene hosts. The detection of residual ARGs and OTUs related to potentially pathogenic genera such as Clostridium butyricum and Terrisporobacter glycolicus species in the treated effluent raises concerns about the final disposal of this waste, given the possibility of horizontal gene transfer in the environment.202541145054
7058130.9906Does organically produced lettuce harbor higher abundance of antibiotic resistance genes than conventionally produced? The demand for organic food products, especially for organic vegetables has been growing rapidly in the last few decades. However, the risk of introducing more antibiotic resistant genes (ARGs) and antibiotic resistant bacteria (ARB) to the vegetables by organic production procedures has long been overlooked. In our study, by using high-throughput quantitative PCR and 16sRNA Illumina sequencing technology, we investigated the abundance and diversity of ARGs and the microbial communities in conventionally (CPL) and organically produced lettuce (OPL). A total of 134 ARGs were detected in the phyllosphere and leaf endophyte of the samples. Absolute copy numbers of ARGs in phyllosphere were 8-fold higher in the OPL than in CPL. We also observed a significant difference in the microbial communities between OPL and CPL, and a lower diversity of both phyllosphere and leaf endophytic bacteria in OPL than in CPL. The Mantel test and variation partitioning analysis (VPA) suggested that the profile of ARGs is strongly affected by bacterial community compositions. Network analysis between ARGs and bacterial taxa indicated that eight bacterial families were implicated to be the potential hosts of ARGs. These results provide insights into the impacts of organic farming on the profiles of bacterial and ARG compositions in vegetables.201727823798
7057140.9905Enrichment of antibiotic resistance genes in soil receiving composts derived from swine manure, yard wastes, or food wastes, and evidence for multiyear persistence of swine Clostridium spp. The impact of amendment with swine manure compost (SMC), yard waste compost (YWC), or food waste compost (FWC) on the abundance of antibiotic resistance genes in soil was evaluated. Following a commercial-scale application of the composts in a field experiment, soils were sampled periodically for a decade, and archived air-dried. Soil DNA was extracted and gene targets quantified by qPCR. Compared with untreated control soil, all 3 amendment types increased the abundance of gene targets for up to 4 years postapplication. The abundance of several gene targets was much higher in soil amended with SMC than in soil receiving either YWC or FWC. The gene target ermB remained higher in the SMC treatment for a decade postapplication. Clostridia were significantly more abundant in the SMC-amended soil throughout the decade following application. Eight percent of Clostridium spp. isolates from the SMC treatment carried ermB. Overall, addition of organic amendments to soils has the potential to increase the abundance of antibiotic resistance genes. Amendments of fecal origin, such as SMC, will in addition entrain bacteria carrying antibiotic resistance genes. Environmentally recalcitrant clostridia, and the antibiotic resistance genes that they carry, will persist for many years under field conditions following the application of SMC.201829342372
3542150.9905Fecal indicators, pathogens, antibiotic resistance genes, and ecotoxicity in Galveston Bay after Hurricane Harvey. Unprecedented rainfall after Hurricane Harvey caused a catastrophic flood in the southern coast of Texas, and flushed significant floodwater and sediments into Galveston Bay, the largest estuary along the Texas Gulf Coast. This study investigated the immediate and long-term (6 months post-Harvey) fecal indicators, pathogenic bacteria, antibiotic resistance genes (ARGs), and ecotoxicity in the Galveston Bay. Dramatic decrease of salinity profile to zero, increased levels of fecal indicator bacteria and pathogenic bacteria, and detection of various ARGs were observed in the water and sediment samples collected 2 weeks post-Harvey. High levels of Bla(TEM) and cytotoxicity measured by yeast bioluminescent assay (BLYR) were also observed especially near the river mouths. While Vibrio spp. was dominant in water, much higher abundance of fecal indicator bacteria and pathogen were detected in the sediments. A decreasing trend of Bla(TEM) and cytotoxicity was observed in March 2018 samples, suggesting the Bay has returned to its pre-hurricane conditions 6 months post-Harvey. Interestingly, the abundance of fecal indicator bacteria and pathogens were shifted dramatically according to high-streamflow and low-streamflow seasons in the Bay. The data are useful to construct the model of risk assessment in coastal estuaries system and predict the effects of extreme flooding events in the future.202133445049
6871160.9905Distinct 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
7217170.9905Emission and dispersal of antibiotic resistance genes through bioaerosols generated during the treatment of municipal sewage. Wastewater treatment plants act as socio-ecological couplers through the concentration, treatment, and subsequent environmental release of sewage collected from surrounding communities and are often considered hotspots for antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs). While studies have identified the release of ARB/ARGs in treated liquid sewage, little is known about potential dispersal through wastewater bioaerosol emissions. The aim of this study was to better define the contribution of WWTP bioaerosols to potential environmental distribution of ARB/ARGs. Bioaerosols were collected immediately upwind and downwind from the aeration tanks of a municipal wastewater treatment plant and liquid sludge samples were obtained from the aeration tanks. From the bioaerosol and liquid samples, qPCR assays identified 44 ARGs that confer resistance to a wide range of antibiotics. Comparison of the ARG profiles across samples showed that the downwind bioaerosol profile was 68% similar to the profile found in liquid sludge samples. Community 16S rRNA gene sequencing also showed that downwind bioaerosols had similar taxonomic profiles as those generated from liquid sludge while the upwind profiles showed a distinct difference. Preliminary ARG dispersion modeling estimated an ARG emission rate of ~10,620 genes per hour from the liquid sludge and indicated that the bioaerosols have the potential to be carried kilometers away from the WWTP source based on wind speed. The overall results from this study suggest that bioaerosols generated during WWTP processes can aid in the emission and dispersal of bacteria and ARGs, resulting in a possible route of human exposure and deposition into surrounding environments.201931181526
7351180.9904Dynamics of integron structures across a wastewater network - Implications to resistance gene transfer. Class 1 and other integrons are common in wastewater networks, often being associated with antibiotic resistance genes (ARGs). However, the importance of different integron structures in ARG transfer within wastewater systems has only been implied, especially between community and hospital sources, among wastewater treatment plant compartments, and in receiving waters. This uncertainty is partly because current clinical class 1 integron qPCR assays (i.e., that target human-impacted structures, i.e., clintI1) poorly delineate clintI1 from non-impacted class 1 integron structures. They also say nothing about their ARG content. To fill these technical gaps, new real-time qPCR assays were developed for "impacted" class 1 structures (called aint1; i.e., anthropogenic class 1 integrons) and empty aint1 structures (i.e., carry no ARGs; called eaint1). The new assays and other integron assays then were used to examine integron dynamics across a wastewater network. 16S metagenomic sequencing also was performed to characterise associated microbiomes. aint1 abundances per bacterial cell were about 10 times greater in hospital wastewaters compared with other compartments, suggesting aint1 enrichment with ARGs in hospital sources. Conversely, the relative abundance of eaint1 structures were over double in recycled activated sludge compared with other compartments, except receiving waters (RAS; ∼30% of RAS class 1 structures did not carry ARGs). Microbiome analysis showed that human-associated bacterial taxa with mobile integrons also differed in RAS and river sediments. Further, class 1 integrons in RAS bacteria appear to have released ARGs, whereas hospital bacteria have accumulated ARGs. Results show that quantifying integron dynamics can help explain where ARG transfer occurs in wastewater networks, and should be considered in future studies on antibiotic resistance in the environment.202134673462
7357190.9904Metagenomic surveys show a widespread diffusion of antibiotic resistance genes in a transect from urbanized to marine protected area. Ports are hot spots of pollution; they receive pollution from land-based sources, marine traffic and port infrastructures. Marine ecosystems of nearby areas can be strongly affected by pollution from port-related activities. Here, we investigated the microbiomes present in sea floor sediments along a transect from the harbour of Livorno (Central Italy) to a nearby marine protected area. Results of 16S rRNA amplicon sequencing and metagenome assembled genomes (MAGs) analyses indicated the presence of different trends of specific bacterial groups (e.g. phyla NB1-j, Acidobacteriota and Desulfobulbales) along the transect, correlating with the measured pollution levels. Human pathogenic bacteria and antibiotic resistance genes (ARGs) were also found. These results demonstrate a pervasive impact of human port activities and highlight the importance of microbiological surveillance of marine sediments, which may constitute a reservoir of ARGs and pathogenic bacteria.202539908950