Accumulation Of Antibiotic Resistance Genes Research Articles

Construction and characterization of sodium alginate/polyvinyl alcohol double-network hydrogel beads with surfactant-tailored adsorption capabilities for efficient tetracycline hydrochloride removal

The extensive use of tetracycline (TC) for disease control and the residuals in wastewater has resulted in the spread and accumulation of antibiotic resistance genes, posing a severe threat to the human health and environmental safety. To solve this problem, a series of double-network hydrogel beads based on sodium alginate and polyvinyl alcohol were constructed with the introduction of various surfactants to modulate the morphology. The results showed that the introduction of surfactants can modulate the surface morphology and internal structure, which can also regulate the adsorption ability of the hydrogel beads. The SDS-B beads with SDS as surfactant exhibited highest adsorption efficiency for removal of TC with a maximum adsorption capacity up to 121.6 mg/g, which possessed a resistance to various cations and humic acid. The adsorption mechanism revealed that the superior adsorption performance of the hydrogel beads was primarily attributed to hydrogen bonding, electrostatic attraction, and π-π EDA interactions. Adsorption kinetics demonstrated that the pseudo-second-order model fitted the adsorption process well and adsorption isotherm showed the adsorption of TC occurred through both chemical and physical interactions. Moreover, the adsorption efficiency remained approximately 87.5 % after three adsorption-desorption cycles, which may have potential application and practical value in TC adsorption.

Metabolism of nitrogen and sulfamethoxazole, performance recovery mechanism, and antibiotic resistance genes (ARGs) behaviors in membrane aerated biofilm reactor (MABR)

The limited information on micro-mechanism of sulfamethoxazole (SMX) metabolism and antibiotics resistance genes (ARGs) behaviors within membrane-aerated biofilm reactor (MABR) blocked the application of MABR in treating antibiotics containing wastewater. In this work, SMX metabolism and the changes of ARGs were investigated in MABR during 0.0-0.7 mg/L SMX. The system achieved a 92.3% SMX removal at 0.7 mg/LSMX, leading to the formation of 17 lower toxic metabolites, which indicated the robust SMX biodegradation capability of MABR. The metabolic pathways of SMX in MABR were first elucidated, revealing key processes including isoxazole ring opening (primarily in anaerobic zones), aniline hydroxylation, and cleavage of the S-N bond in the sulfonyl group. Microbial analysis revealed the involvement of multiple microbes in SMX biodegradation, and among these, sulfate-reducing bacteria (SRB; Desulfovibrio, Desulforhopalus, Desulfomicrobium) facilitated the isoxazole ring opening in the anaerobic zone, while Rhizobium and Chryseobacterium contributed to ipso-hydroxylation and cleavage of the -C-S-N bond in SMX, respectively. Furthermore, the slower accumulation of ARGs under SMX conditions was primarily attributed to the enhanced efflux pump activity, antibiotic target replacement mechanisms, and secretion of extracellular polymeric substances (EPS), suggesting the potential of MABR to inhibit ARG proliferation. Our research filled the knowledge gap in the micro-mechanism of SMX metabolism and ARGs fate within MABR processing SMX-containing wastewater, laying a theoretical foundation for the broader application of MABR in practical engineering.

Antibiotic resistomes and ecological risk elimination in field-scale constructed wetland revealed by integrated metagenomics and metatranscriptomics

Constructed wetlands (CWs) are identified as significant ecological systems for the potential control of antibiotic resistance genes (ARGs) in the environment. However, the precise mechanisms governing removal, persistence, expression, and associated risks of ARGs during wetland treatment remain poorly understood. In this study, the distribution, mobility, expression, and hosts of ARGs in water, sediments, and plants of a field-scale CW and its parallel natural river were systematically investigated through metagenomic and metatranscriptomic approaches. Results showed that both the abundance and diversity of ARGs in water gradually decreased along the way of CW, reaching a final abundance removal rate of 72.28 % in the effluent. Source tracking analysis indicted that the reduction of ARGs in water was mainly achieved by the dynamic accumulation of ARGs in sediments and plants of the CW. Proteobacteria were identified as primary hosts for ARGs, particularly in sediments and plants during CW treatment. Moreover, although ESKAPE pathogens carrying multiple ARGs persisted in all media throughout the CW treatment, ARG expression levels and risk of water were also significantly decreased after CW treatment. Collectively, our comprehensive multi-omics study would enhance the understanding of ARG removal by CWs, offering insights for controlling antimicrobial resistance in wastewater treatment system.

Applications of different forms of nitrogen fertilizers affect soil bacterial community but not core ARGs profile.

The objective of this study was to investigate the impact of various chemical nitrogen fertilizers on the profile of antibiotic resistance genes (ARGs) in soil. A microcosm experiment was conducted with four treatments, including CK (control with no nitrogen), AN (ammonium nitrogen), NN (nitrate nitrogen), and ON (urea nitrogen), and the abundance of ARGs was assessed over a 30-day period using a metagenomic sequencing approach. The levels of core ARGs varied between 0.16 and 0.22 copies per cell across different treatments over time. The abundance of core ARGs in the ON treatment closely resembled that of the CK treatment, suggesting that environmentally friendly nitrogen fertilizers, particularly those in controlled release formulations, may be preferable. The core ARG abundance in the AN and NN treatments exhibited noticeable fluctuations over time. Overall, chemical nitrogen fertilizers had minimal effects on the core ARG profile as determined by principal component analysis and clustering analyses. Conversely, distinct and significant changes in bacterial communities were observed with the use of different nitrogen fertilizers. However, the influence of nitrogen fertilizers on the core ARGs is limited due to the unaffected potential bacterial hosts. Nitrogen-cycling-related genes (NCRGs), such as those involved in nitrogen-fixing (nifK, nifD, nifH) and denitrification (narG, napA, nirK, norB, nosZ) processes, exhibit a positive correlation with ARGs (rosA, mexF, bacA, vanS), indicating a potential risk of ARG proliferation during intense denitrification activities. This study indicates that the application of chemical nitrogen has a minimal effect on the abundance of ARGs in soil, thereby alleviating concerns regarding the potential accumulation of ARGs due to the use of chemical nitrogen fertilizers.

Exploring the antibiotic resistance genes removal dynamics in chicken manure by composting

Prolonged antibiotic usage in livestock farming leads to the accumulation of antibiotic resistance genes in animal manure. Composting has been shown as an effective way of removing antibiotic resistance from manures, but the specific mechanisms remain unclear. This study used time-series sampling and metagenomics to analyse the resistome types and their bacterial hosts in chicken manures. Composting significantly altered the physicochemical properties and microbiome composition, reduced antibiotic resistance genes by 65.71 %, mobile genetic elements by 68.15 % and horizontal gene transfer frequency. Source tracking revealed that Firmicutes, Actinobacteria, and Proteobacteria are the major bacterial hosts involved in the resistome and gene transfer events. Composting reduces the resistome risk by targeting pathogens such as Staphylococcus aureus. Structural equation modelling confirmed that composting reduces resistome risk by changing pH and pathogen abundance. This study demonstrates that composting is an effective strategy for mitigating resistome risk in chicken manure, thereby supporting the One Health initiative.

Deciphering the adaptation mechanism of anammox consortia under sulfamethoxazole stress: A model coupling resistance accumulation and interspecies-cooperation

Sulfamethoxazole (SMX) is frequently detected in wastewater where anammox applications are promising. While it has been demonstrated that anammox consortia can adapt to SMX stress, the underlying community adaptation strategy has not yet been fully addressed. Therefore, in this study, we initially ascertained anammox consortia’s ability to co-metabolize SMX in batch tests. Then, a 200-day domestication process of anammox consortia under SMX stress was carried out with community variations and transcriptional activities monitored by metagenomic and metatranscriptomic sequencing techniques. Despite the initial drop to 41.88 %, the nitrogen removal efficiency of the anammox consortia rebounded to 84.64 % post-domestication under 5 mg/L SMX. Meanwhile, a 4.85-fold accumulation of antibiotic resistance genes (ARGs) under SMX stress was observed as compared to the control group. Interestingly, the anammox consortia may unlock the SMX-inhibited folate synthesis pathway through a novel interspecies cooperation triangle among Nitrospira (NAA), Desulfobacillus denitrificans (DSS1), and the core anammox population Candidatus Brocadia sinica (AMX1), in which the modified dihydropteroate synthase (encoded by sul1) of NAA reconnected the symbiotic cooperation between AMX1 and DSS1. Overall, this study provides a new model for the adaptation strategies of anammox consortia to SMX stress.

Sewage Sludge Promotes the Accumulation of Antibiotic Resistance Genes in Tomato Xylem.

Xylem serves as a conduit linking soil to the aboveground plant parts and facilitating the upward movement of microbes into leaves and fruits. Despite this potential, the composition of the xylem microbiome and its associated risks, including antibiotic resistance, are understudied. Here, we cultivated tomatoes and analyzed their xylem sap to assess the microbiome and antibiotic resistance profiles following treatment with sewage sludge. Our findings show that xylem microbes primarily originate from soil, albeit with reduced diversity in comparison to those of their soil microbiomes. Using single-cell Raman spectroscopy coupled with D2O labeling, we detected significantly higher metabolic activity in xylem microbes than in rhizosphere soil, with 87% of xylem microbes active compared to just 36% in the soil. Additionally, xylem was pinpointed as a reservoir for antibiotic resistance genes (ARGs), with their abundance being 2.4-6.9 times higher than in rhizosphere soil. Sludge addition dramatically increased the abundance of ARGs in xylem and also increased their mobility and host pathogenicity. Xylem represents a distinct ecological niche for microbes and is a significant reservoir for ARGs. These results could be used to manage the resistome in crops and improve food safety.

Field-based investigation reveals selective enrichment of companion microbes in vegetables leading to specific accumulation of antibiotic resistance genes

Vegetables capture antibiotic resistance genes (ARGs) from the soil and then pass them on to consumers through the delivery chain and food chain, and are therefore the key node that may increase the risk of human exposure to ARGs. This study investigates the patterns and driving forces behind the transmission of ARGs from soil to vegetables by the commonly planted cash crops in the coastal region of southern China, i.e. broccoli, pumpkin, and broad bean, to investigate. The study used metagenomic data to reveal the microbial and ARGs profiles of various vegetables and the soil they are grown. The results indicate significant differences in the accumulation of ARGs among different vegetables harvested in the same area at the same time frame, and the ARGs accumulation ability of the three vegetables was in the order of broccoli, broad bean, and pumpkin. In addition, broccoli collected the highest number of ARGs in types (n = 14), while pumpkin (n = 13) does not obtain trimethoprim resistance genes and broad beans (n = 10) do not obtain chloramphenicol, fosmidomycin, quinolone, rifamycin, or trimethoprim resistance genes. Host tracking analysis shows a strong positive correlation (|rho| > 0.8, p < 0.05) between enriched ARGs and plant companion microbes. Enrichment analysis of metabolic pathways of companion microbes shows that vegetables exhibit a discernible enrichment of companion microbes, with significant differences among vegetables. This phenomenon is primarily due to the screening of carbohydrate metabolism capabilities among companion microbes and leads varied patterns of ARGs that spread from the soil to vegetables. This offers a novel insight into the intervention of foodborne transmission of ARGs.

Linking bacterial life strategies with the distribution pattern of antibiotic resistance genes in soil aggregates after straw addition

Straw addition markedly affects the soil aggregates and microbial community structure. However, its influence on the profile of antibiotic resistance genes (ARGs), which are likely associated with changes in bacterial life strategies, remains unclear. To clarify this issue, a soil microcosm experiment was incubated under aerobic (WS) or anaerobic (AnWS) conditions after straw addition, and metagenomic sequencing was used to characterise ARGs and bacterial communities in soil aggregates. The results showed that straw addition shifted the bacterial life strategies from K- to r-strategists in all aggregates, and the aerobic and anaerobic conditions stimulated the growth of aerobic and anaerobic r-strategist bacteria, respectively. The WS decreased the relative abundances of dominant ARGs such as QnrS5, whereas the AnWS increased their abundance. After straw addition, the macroaggregates consistently exhibited a higher number of significantly altered bacteria and ARGs than the silt+clay fractions. Network analysis revealed that the WS increased the number of aerobic r-strategist bacterial nodes and fostered more interactions between r-and K-strategist bacteria, thus promoting ARGs prevalence, whereas AnWS exhibited an opposite trend. These findings provide a new perspective for understanding the fate of ARGs and their controlling factors in soil ecosystems after straw addition. Environmental implicationsStraw soil amendment has been recommended to mitigate soil fertility degradation, improve soil structure, and ultimately increase crop yields. However, our findings highlight the importance of the elevated prevalence of ARGs associated with r-strategist bacteria in macroaggregates following the addition of organic matter, particularly fresh substrates. In addition, when assessing the environmental risk posed by ARGs in soil that receives crop straw, it is essential to account for the soil moisture content. This is because the species of r-strategist bacteria that thrive under aerobic and anaerobic conditions play a dominant role in the dissemination and accumulation of ARG.

Typical antibiotic resistance genes and their association with driving factors in the coastal areas of Yangtze River Estuary.

The massive use of antibiotics has led to the escalation of microbial resistance in aquatic environment, resulting in an increasing concern regarding antibiotic resistance genes (ARGs), posing a serious threat to ecological safety and human health. In this study, surface water samples were collected at eight sampling sites along the Yangtze River Estuary. The seasonal and spatial distribution patterns of 10 antibiotics and target genes in two major classes (sulfonamides and tetracyclines) were analyzed. The findings indicated a high prevalence of sulfonamide and tetracycline resistance genes along the Yangtze River Estuary. Kruskal-Wallis analysis revealed significant seasonal variations in the abundance of all target genes. The accumulation of antibiotic resistance genes in the coastal area of the Yangtze River Estuary can be attributed to the influence of urban instream runoff and the discharge of effluents from wastewater treatment plants. ANISOM analysis indicated significant seasonal differences in the microbial community structure. VPA showed that environmental factors contribute the most to ARG variation. PLS-PM demonstrate that environmental factors and microbial communities pose direct effect to ARG variation. Analysis of driving factors influencing ARGs in this study may shed new insights into the mechanism of the maintenance and propagation of ARGs.

Nano-CeO2 activates physical and chemical defenses of garlic (Allium sativum L.) for reducing antibiotic resistance genes in plant endosphere

The transmission of manure- and wastewater-borne antibiotic-resistant bacteria (ARB) to plants contributes to the proliferation of antimicrobial resistance in agriculture, necessitating effective strategies for preventing the spread of antibiotic resistance genes (ARGs) from ARB in the environment to humans. Nanomaterials are potential candidates for efficiently controlling the dissemination of ARGs. The present study investigated the abundance of ARGs in hydroponically grown garlic (Allium sativum L.) following nano-CeO2 (nCeO2) application. Specifically, root exposure to nCeO2 (1, 2.5, 5, 10 mg L−1, 18 days) reduced ARG abundance in the endosphere of bulbs and leaves. The accumulation of ARGs (cat, tet, and aph(3’)-Ia) in garlic bulbs decreased by 24.2–32.5 % after nCeO2 exposure at 10 mg L−1. Notably, the lignification extent of garlic stem-disc was enhanced by 10 mg L−1 nCeO2, thereby accelerating the formation of an apoplastic barrier to impede the upward transfer of ARG-harboring bacteria to garlic bulbs. Besides, nCeO2 upregulated the gene expression related to alliin biosynthesis and increased allicin content by 15.9–16.2 %, promoting a potent antimicrobial defense for reducing ARG-harboring bacteria. The potential exposure risks associated with ARGs and Ce were evaluated according to the estimated daily intake (EDI). The EDI of ARGs exhibited a decrease exceeding 95 %, while the EDI of Ce remained below the estimated oral reference dose. Consequently, through stimulating physical and chemical defenses, nCeO2 contributed to a reduced EDI of ARGs and Ce, highlighting its potential for controlling ARGs in plant endosphere within the framework of nano-enabled agrotechnology.

Removal of antibiotics, bacterial toxicity, and occurrence of antibiotic resistance genes in secondary hospital effluents treated with granular activated carbon and the impact of preceding chlorination

This comprehensive investigation highlighted the complex adsorption behaviors of antibiotics onto granular activated carbon (GAC), the effectiveness of this adsorption in reducing bacterial toxicity, and the reduction of antibiotic resistance genes (ARGs) and antibiotic resistant bacteria (ARB) in hospital wastewater (HWW) effluents. Six GACs were characterized for their physicochemical properties, and their ability to adsorb six antibiotics in the background matrix of actual HWW was evaluated. Coconut shell-derived GAC (Co-U), which had the highest hydrophobicity and lowest content of oxygen-containing acidic functional groups, demonstrated the highest adsorption capacities for the tested antibiotics. Bacterial toxicity tests revealed that GACs could eliminate the bacterial toxicity from antibiotic intermediates present in chlorinated HWW. By contrast, the bacterial toxicity could not be removed by GACs in non-chlorinated HWW due to the greater presence of intermediate components identified by LC-MS/MS. The intraparticle diffusion coefficient of antibiotics adsorbed onto Co-U could be calculated by adsorption kinetics derived from the linear driving force model and the homogenous intraparticle diffusion model associated with the linear adsorption isotherms (0–150 μg/L). Meropenem and sulfamethoxazole exhibited the highest adsorption capacities in a single-solute solution compared to penicillin G, ampicillin, cetazidime, and ciprofloxacin. However, the greater adsorption capacities of meropenem and sulfamethoxazole disappeared in mixed-solute solutions, indicating the lowest adsorption competition. GAC can eliminate most ARGs while also promoting the growth of some ARB. Chlorination (free chlorine residues at 0.5 mg Cl2/L) did not significantly affect the overall composition of ARGs and ARB in HWW. However, the accumulation of ARGs and ARB on GAC in fixed bed columns was lower in chlorinated HWW than in non-chlorinated HWW due to an increase in the adsorption of intermediates.

Urbanization influences the indoor transfer of airborne antibiotic resistance genes, which has a seasonally dependent pattern

Over the last few years, the cumulative use of antibiotics in healthcare institutions, as well as the rearing of livestock and poultry, has resulted in the accumulation of antibiotic resistance genes (ARGs). This presents a substantial danger to human health worldwide. The characteristics of airborne ARGs, especially those transferred from outdoors to indoors, remains largely unexplored in neighborhoods, even though a majority of human population spends most of their time there. We investigated airborne ARGs and mobile genetic element (MGE, IntI1), plant communities, and airborne microbiota transferred indoors, as well as respiratory disease (RD) prevalence using a combination of metabarcode sequencing, real-time quantitative PCR and questionnaires in 72 neighborhoods in Shanghai. We hypothesized that (i) urbanization regulates ARGs abundance, (ii) the urbanization effect on ARGs varies seasonally, and (iii) land use types are associated with ARGs abundance. Supporting these hypotheses, during the warm season, the abundance of ARGs in peri-urban areas was higher than in urban areas. The abundance of ARGs was also affected by the surrounding land use and plant communities: an increase in the proportion of gray infrastructure (e.g., residential area) around neighborhoods can lead to an increase in some ARGs (mecA, qnrA, ermB and mexD). Additionally, there were variations observed in the relationship between ARGs and bacterial genera in different seasons. Specifically, Stenotrophomonas and Campylobacter were positively correlated with vanA during warm seasons, whereas Pseudomonas, Bacteroides, Treponema and Stenotrophomonas positively correlated with tetX in the cold season. Interstingly, a noteworthy positive correlation was observed between the abundance of vanA and the occurrence of both rhinitis and rhinoconjunctivitis. Taken together, our study underlines the importance of urbanization and season in controlling the indoor transfer of airborne ARGs. Furthermore, we also highlight the augmentation of green–blue infrastructure in urban environments has the potential to mitigate an excess of ARGs.

The effects of cadmium-copper stress on the accumulation of antibiotic-resistance genes in soil and pakchoi leaves

Antibiotic resistance and heavy metal contamination are two worldwide environmental concerns. Especially in soil, the interaction between these two pollutants may exacerbate the problem of antibiotic resistance genes (ARGs) entering the food chain, which can have severe consequences on the environment and the wellness of humankind. This study investigated the influences of cadmium (Cd) and copper (Cu) pollution on ARG profiles in the soil rhizosphere and endogenous microbiome of roots and leaves in pakchoi. We further determined the impact of these heavy metals and various environmental factors on the accumulation of ARGs in leaves and discussed the possible transfer pathways of ARGs in the soil-plant system. Our results showed that Cd–Cu stress increased the relative abundance of most target genes in the samples, especially the sulfonamide resistance genes sul1 and sul3, the quinolone resistance gene qepA, and the Class 1 integron integrase gene intI1. Variance partitioning analysis indicated that the Cd–Cu contents primarily contributed (45.7%) to ARG variations in leaves. Cadmium and Cu led to a pollution-induced community tolerance phenomenon in microbial communities, enriching Cd- and Cu-tolerant bacteria. ARGs were highly correlated with mobile genetic elements (e.g., intI1) and metal resistance genes, increasing the co-selection of metals on ARGs. Structural equation modeling showed that metal resistance genes and intI1 in leaves had significant direct positive effects on the relative abundances of ARGs (p < 0.05). Higher Cu concentrations facilitated the migration of most target ARGs from soil to leaves.

Environmental factors dominate microbial community puppet-like driving the distribution of antibiotic resistance genes in different utilization lands

Excessive use of antibiotics has caused the accumulation of antibiotic resistance genes (ARGs) in the soil environment, posing a great challenge to environmental safety and public health. However, there is a lack of comprehensive investigations of soil ARGs profiles under different land utilization patterns, and the drivers that affect the distribution of ARGs remain poorly defined. Herein, we investigated the ARGs profiles of eight different land uses and explored the critical factors influencing the distribution of ARGs. The results showed that ARGs abundance in soil of parks, residential areas, farmland, and vegetable cultivation was significantly higher than that in other lands, with an average of 2.08 × 103 copies/g dry soil. The structural equation model demonstrated that the environmental variables were the pivotal drivers that dominated the differences in ARG distribution across land utilization types (path coefficient=0.934), in which the physicochemical factors exhibited the greatest contribution with an explanatory rate of 20.27%, which was markedly higher than that of antibiotics and heavy metal residues. Importantly, these physicochemical factors manipulate the succession of microbial communities by altering the connections between microorganisms, which in turn indirectly affects the distribution of ARGs. Moreover, ARG exposure was strongly correlated with fertilizer application, precipitation, and per capita water resources (p < 0.01). Overall, this study provides a well-rounded understanding of ARG exposure under different land-use patterns, which helps to develop management strategies for curbing ARGs dissemination in the environment.

Transfer and accumulation of antibiotic resistance genes and bacterial pathogens in the mice gut due to consumption of organic foods

Over the last few decades, organic food demand has grown largely because of increasing personal health concerns. Organic farming introduces antibiotic resistance genes (ARGs) and antibiotic-resistant bacteria (ARB) into foods. However, potential effects of organic foods on the gut microbiome and ARGs have been overlooked. Using high-throughput quantitative PCR and 16S rRNA high-throughput sequencing technology, we examined 132 ARGs from major classes, eight transposase genes, universal class I integron-integrase gene (intI), clinical class I integron-integrase gene (cintI), and the bacterial community in mouse gut after 8 weeks with an either organic or inorganic lettuce and wheat diet. A total of 8 types of major ARGs and 10 mobile genetic elements (MGEs) were detected in mice gut, including tetracycline, multidrug, sulfonamide, aminoglycoside, beta-lactamase, chloramphenicol, MLSB and vancomycin resistance genes. We found that abundance and diversity of ARGs, mobile gene elements, and potential ARB in the gut increased with time after consumption of organic foods, whereas no significant changes were observed in inorganic treated groups. Moreover, MGEs, including IS613, Tp614 and tnpA_03 were found to play an important role in regulating ARG profiles in the gut microbiome following consumption of organic foods. Importantly, feeding organic food increased the relative abundance of the potentially antibiotic-resistant pathogens, Bacteroides and Streptococcus. Our results confirm that there is an increasing risk of ARGs and ARB in the gut microbiome, which highlights the importance of organic food industries taking into account the potential accumulation and transmission of ARGs as a risk factor.

Long-term application of organic fertilizer prompting the dispersal of antibiotic resistance genes and their health risks in the soil plastisphere

Microplastic (MP) pollution is a rapidly growing global environmental concern that has led to the emergence of a new environmental compartment, the plastisphere, which is a hotspot for the accumulation of antibiotic resistance genes (ARGs) and human bacterial pathogens (HBPs). However, studies on the effects of long-term organic fertilizer application on the dispersal of ARGs and virulence factor genes (VFGs) in the plastisphere of farmland soil have been limited. Here, we performed a field culture experiment by burying nylon bags filled with MPs in paddy soil that had been treated with different fertilizers for over 30 years to explore the changes of ARGs and VFGs in soil plastisphere. Our results show that the soil plastisphere amplified the ARG and VFG pollution caused by organic fertilization by 1.5 and 1.4 times, respectively. And it also led to a 2.7-fold increase in the risk of horizontal gene transfer. Meanwhile, the plastisphere tended to promote deterministic process in the community assembly of HBPs, with an increase of 1.4 times. Network analysis found a significant correlation between ARGs, VFGs, and bacteria in plastisphere. Correlation analysis highlight the important role of mobile genetic elements (MGEs) and bacterial communities in shaping the abundance of ARGs and VFGs, respectively. Our findings provide new insights into the health risk associated with the soil plastisphere due ARGs and VFGs derived from organic fertilizers.

Transfer, elimination and accumulation of antibiotic resistance genes in decentralized household wastewater treatment facility treating total wastewater from residential complex

The fate and behavior of antibiotic resistance genes (ARGs) in decentralized household wastewater treatment facilities (DHWWTFs) are unclear. In this study, targeting on a representative DHWWTF that receive all wastewater from a residential complex having 150 households, the transfer, elimination and accumulation of tetG, tetM, sul1, sul2 and intl1 were quantitively studied through real-time PCR-based quantification, mass balance evaluation and the existing state analysis based on size fractionation. Significant abundance changes of the genes were observed in involved biological reactions and the sedimentation process due to microbial growth and decomposition as well as the accumulation of the genes to sludge. tetG and sul1 increased in their fluxes against respective input in the influent. Although substantial portions of the increased genes were found in excess sludge compared to the flux of genes in the influent, those remaining in the discharge were still high, with an average about 3.4 × 1014 copies/d. The abundance of all four genes (tetG, tetM, sul1and sul2) in both water and sludge phases showed a general trend of reduction as sludge accumulated gradually in its storage tank within two months after desludging. Classification of ARGs based on particle sizes (>250 μm, 125–250 μm, 75–125 μm, 25–75 μm, 3–25 μm, <3 μm) indicated that while the major part of ARGs were distributed in particles with larger sizes (125–250 μm), ARGs in smaller particles (3–25 μm) and free ARGs (<3 μm) still existed, which may pose a greater threat to water environment due to their poor settleability. The results of this study can benefit the optimization of on-site maintenance and operation of decentralized wastewater treatment facility for elimination of the transfer of ARGs.

Microplastics shape microbial interactions and affect the dissemination of antibiotic resistance genes in different full-scale wastewater treatment plants

Wastewater treatment plants (WWTPs) pose a potential threat to the environment because of the accumulation of antibiotic resistance genes (ARGs) and microplastics (MPs). However, the interactions between ARGs and MPs, which have both indirect and direct effects on ARG dissemination in WWTPs, remain unclear. In this study, spatiotemporal variations in different types of MPs, ten ARGs (sul1, sul2, tetA, tetO, tetM, tetX, tetW, qnrS, ermB, and ermC), class 1 integron integrase (intI1) and transposon Tn916/1545 in three typical WWTPs were characterized. Sul1, tetO, and sul2 were the predominant ARGs in the targeted WWTPs, whereas the intI1 and transposon Tn916/1545 were positively correlated with most of the targeted ARGs. Saccharimonadales (4.15 %), Trichococcus (2.60 %), Nitrospira (1.96 %), Candidatus amarolinea (1.79 %), and SC-I-84 (belonging to phylum Proteobacteria) (1.78 %) were the dominant genera. Network and redundancy analyses showed that Trichococcus, Faecalibacterium, Arcobacter, and Prevotella copri were potential hosts of ARGs, whereas Candidatus campbellbacteria and Candidatus kaiserbacteria were negatively correlated with ARGs. The potential hosts of ARGs had a strong positive correlation with polyethylene terephthalate, silicone resin, and fluor rubber and a negative correlation with polyurethane. Candidatus campbellbacteria and Candidatus kaiserbacteria were positively correlated with polyurethane, whereas potential hosts of ARGs were positively correlated with polypropylene and fluor rubber. Structural equation modeling highlighted that intI1, transposon Tn916/1545 and microbial communities, particularly microbial diversity, dominated the dissemination of ARGs, whereas MPs had a significant positive correlation with microbial abundance. Our study deepens the understanding of the relationships between ARGs and MPs in WWTPs, which will be helpful in designing strategies for inhibiting ARG hosts in WWTPs.

Ozone micron bubble pretreatment for antibiotic resistance genes reduction in hospital wastewater treatment

Ozone micron bubble (OMB) treatment offers a promising approach to effectively eliminate Antibiotic Resistance Genes (ARGs) from infectious medical wastewater and mitigate the threat of drug resistance transmission. This study evaluated the effectiveness of OMB treatment for reducing ARGs from infectious medical wastewater in laboratory and on-site pilot treatment setups. In part, the presence of antibiotic residues in a hospital wastewater treatment plant (WWTP) and the impact of hospital wastewater on the distribution of ARGs in a wastewater collection system were also investigated. The results of wastewater collection system survey revealed a high prevalence of ARGs in the system, particularly mcr-1, largely originating from medical wastewater discharges. Furthermore, analysis of antibiotic residues in the hospital wastewater treatment system showed significant accumulation, particularly of quinolone antibiotics, in the biomass of the biological oxidation tank, suggesting a potential risk of ARG proliferation within the system. Comparison of wastewater samples from domestic and hospital WWTPs revealed a relatively higher abundance of ARGs in the latter, with differences ranging from 2.2 to sixfold between corresponding locations in the treatment plants. Notably, the biological oxidation unit of both WWTPs exhibited a greater proportion of ARGs among all sampled points, indicating the potential proliferation of ARGs within the biomass of the treatment units. ARG degradation experiments showed that OMB treatment resulted in a significantly lower CT value (9.3 mg O3 L−1 min) compared to ozone coarse bubble treatment (102 mg O3 L−1 min) under identical test conditions. Moreover, the use of OMB on site significantly reduced the accumulation of ARGs in hospital wastewater, underscoring its potential as an effective solution for mitigating ARG spread.