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764200.9848Metagenomics insights into the effects of lactic acid bacteria inoculation on the biological reduction of antibiotic resistance genes in alfalfa silage. Antibiotic resistance genes (ARGs) are a new type of pollutant and pose major threats to public health. However, the distribution and transmission risk of ARGs in alfalfa silage as the main forage for ruminants have not been studied. This study first deciphered the effects of Lactobacillus plantarum MTD/1 or Lactobacillus buchneri 40788 inoculations on distribution and transmission mechanism of ARGs in alfalfa silage by metagenomics. Results showed that multidrug and bacitracin resistance genes were the dominant ARGs in ensiled alfalfa. The natural ensiling process increased the abundances of bacitracin, beta_lactam, and aminoglycoside in alfalfa silage with 30% DM, and vancomycin in alfalfa silage with 40% DM. Meanwhile, prolonged wilting increased ARG enrichment in fresh alfalfa. Interestingly, alfalfa silage inoculated with L. plantarum MTD/1 or L. buchneri 40788 reduced the abundances of total ARG, and multidrug, MLS, vancomycin, aminoglycoside, tetracycline, and fosmidomycin resistance genes by reductions of the host bacteria and the enrichment of ARGs located in the plasmid. The hosts of ARG in alfalfa silage were mainly derived from harmful bacteria or pathogens, and some of the clinical ARGs were observed in alfalfa silage. Basically, the combined effect of microbes, MGEs, and fermentation quality was the major driver of ARG transfer and dissemination in microecosystem of ensiling, where the microbes appeared to be the crucial factor. In summary, inoculation with the present lactic acid bacteria could reduce ARG abundance in ensiled alfalfa, and a better effect was observed in L. plantarum-treated silage than in L. buchneri treated silage.202336444055
764310.9841Heterofermentative Lentilactobacillus buchneri and low dry matter reduce high-risk antibiotic resistance genes in corn silage by regulating pathogens and mobile genetic element. The study of antibiotic resistance in the silage microbiome has attracted initial attention. However, the influences of lactic acid bacteria inoculants and dry matter (DM) content on antibiotic resistance genes (ARGs) reduction in whole-plant corn silage remain poorly studied. This study accessed the ARGs' risk and transmission mechanism in whole-plant corn silage with different DM levels and treated with Lactiplantibacillus plantarum or Lentilactobacillus buchneri. The macrolide and tetracycline were the main ARGs in corn silage. The dominant species (Lent. buchneri and Lactobacillus acetotolerans) were the main ARGs carriers in whole-plant corn silage. The application of Lent. buchneri increased total ARGs abundance regardless of corn DM. Whole-plant corn silage with 30 % DM reduced the abundances of integrase and plasmid compared with 40 % DM. The correlation and structural equation model analysis demonstrated that bacterial community succession, resulting from changes in DM content, was the primary driving factor influencing the ARGs distribution in whole-plant corn silage. Interestingly, whole-plant corn silage inoculated with Lent. buchneri reduced abundances of high-risk ARGs (mdtG, mepA, tetM, mecA, vatE and tetW) by regulating pathogens (Escherichia coli), mobile genetic elements (MGEs) genes (IS3 and IS1182), and this effect was more pronounced at 30 % DM level. In summary, although whole-plant corn silage inoculated with Lent. buchneri increased the total ARGs abundance at both DM levels, it decreased the abundance of high-risk ARGs by reducing the abundances of the pathogens and MGEs, and this effect was more noticeable at 30 % DM level.202439241365
679320.9833Interplays between cyanobacterial blooms and antibiotic resistance genes. Cyanobacterial harmful algal blooms (cyanoHABs), which are a form of microbial dysbiosis in freshwater environments, are an emerging environmental and public health concern. Additionally, the freshwater environment serves as a reservoir of antibiotic resistance genes (ARGs), which pose a risk of transmission during microbial dysbiosis, such as cyanoHABs. However, the interactions between potential synergistic pollutants, cyanoHABs, and ARGs remain poorly understood. During cyanoHABs, Microcystis and high microcystin levels were dominant in all the nine regions of the river sampled. The resistome, mobilome, and microbiome were interrelated and linked to the physicochemical properties of freshwater. Planktothrix and Pseudanabaena competed with Actinobacteriota and Proteobacteria during cyanoHABs. Forty two ARG carriers were identified, most of which belonged to Actinobacteriota and Proteobacteria. ARG carriers showed a strong correlation with ARGs density, which decreased with the severity of cyanoHAB. Although ARGs decreased due to a reduction of ARG carriers during cyanoHABs, mobile gene elements (MGEs) and virulence factors (VFs) genes increased. We explored the relationship between cyanoHABs and ARGs for potential synergistic interaction. Our findings demonstrated that cyanobacteria compete with freshwater commensal bacteria such as Actinobacteriota and Proteobacteria, which carry ARGs in freshwater, resulting in a reduction of ARGs levels. Moreover, cyanoHABs generate biotic and abiotic stress in the freshwater microbiome, which may lead to an increase in MGEs and VFs. Exploration of the intricate interplays between microbiome, resistome, mobilome, and pathobiome during cyanoHABs not only revealed that the mechanisms underlying the dynamics of microbial dysbiosis but also emphasizes the need to prioritize the prevention of microbial dysbiosis in the risk management of ARGs.202337897871
690530.9829The hot air circulation ventilation composting system removes antibiotic resistance genes through competitive inhibition by core bacteria. Livestock manure is a significant reservoir of antibiotic resistance genes (ARGs). Aerobic composting technology can produce mature compost while effectively removing ARGs. In this study, we developed an energy-saving and emission-reducing hot air circulating ventilated composting technology (HACV), which had no adverse effects on the composting process or compost maturity. The HACV composting altered bacterial communities, primarily driven by heterogeneous selection among deterministic factors (65 %). Specifically, it increased the complexity of bacterial networks and promoted the colonization of high-temperature-tolerant bacteria, such as Erysipelothrix, Oceanobacillus and unclassified_f_Bacillaceae. Topological analysis revealed that core bacteria primarily functioned as connectors in composting, serving as important ARGs hosts and facilitating their spread in conventional composting. Among these, a core pathogenic bacterium (Corynebacterium) carried and transmitted ARGs with higher risks. In contrast, although the number of core bacteria (Bacillus, Oceanobacillus, Caldicoprobacter, Saccharomonospora, and Lactobacillus) increased during HACV composting, these bacteria were not potential hosts of the target ARGs. This contributed to the removal of aadE by 80.49 %. Consequently, compared to conventional composting, HACV composting was more effective at controlling risky ARGs, particularly aac(6')-Ib-cr and sul1. Furthermore, the ARGs removal mechanism primarily involved inhibiting horizontal gene transfer (HGT) in HACV composting, attributed to competition between core bacteria and ARGs hosts. In summary, HACV composting effectively promotes ARGs removal and reduces the risk of bacterial resistance. ENVIRONMENTAL IMPLICATION: In this study, we developed an energy-saving and emission-reducing hot air circulation ventilation composting technology (HACV), which effectively removes antibiotic resistance genes (ARGs). The HACV system maintained composting efficiency and maturity while driving bacterial community succession through deterministic processes (heterogeneous selection). HACV composting increased the colonization of core bacteria in the microbial network. Acting as connectors, the core bacteria are not hosts of ARGs in the HACV system, inhibiting horizontal gene transfer (HGT) and remove ARGs through competition with host bacteria.202540682888
696640.9828Effects of Lactic Acid Bacteria Inoculants on Fermentation Quality, Bacteria Communities and Antibiotic Resistance Genes in Whole-Crop Corn Silage. Feed is an important source of antibiotic resistance genes (ARGs) in animals and products, posing significant potential risks to human health and the environment. Ensiling may present a feasible method for reducing ARGs in animal feed. This study involved the addition of four types of lactic acid bacteria (LAB) inoculants, Lactiplantibacillus plantarum (LP), Pediococcus acidilactici (P), Enterococcus faecium (E), and Ligilactobacillus salivarius (LS), to whole-crop corn silage to investigate changes in ARGs, mobile genetic elements (MGEs), and their transmission risks during ensiling. The results indicated that the addition of LAB significantly reduced the ammonia nitrogen content and pH value of whole-crop corn silage, inhibited the growth of harmful microorganisms, and increased the lactic acid content (p < 0.05). The improvement effect was particularly pronounced in the P treatment group. Natural fermentation plays a significant role in reducing ARG abundance, and the addition of different types of lactic acid bacteria helps reduce the abundance of both ARGs and MGEs. Specifically, the LS treatment group exhibited a significant decrease in MGE abundance, potentially reducing the horizontal transmission risk of ARGs. Furthermore, variations in ARG abundance within different LAB strains were detected, showing a consistent trend with that in silage. ARGs and MGEs were correlated with the fermentation parameters and microbial communities (p < 0.05). This suggests that adding LAB with low levels of ARGs to silage can effectively reduce ARG contamination. Bacterial community structure, MGEs, and fermentation quality may act as driving forces for the transfer and dissemination of ARGs in the silage ecosystem.202541011310
696750.9828Effects of Pyroligneous Acid on Diversity and Dynamics of Antibiotic Resistance Genes in Alfalfa Silage. Antibiotic resistance genes (ARGs) are recognized as contaminants due to their potential risk for human and environment. The aim of the present study is to investigate the effects of pyroligneous acid (PA), a waste of biochar production, on fermentation characteristics, diversity, and dynamics of ARGs during ensiling of alfalfa using metagenomic analysis. The results indicated that PA decreased (P < 0.05) dry matter loss, pH value, gas production, coliform bacteria count, protease activity, and nonprotein-N, ammonia-N, and butyric acid contents and increased (P < 0.05) lactic acid content during ensiling. During fermentation, Bacteria, Firmicutes, and Lactobacillus were the most abundant at kingdom, phylum, and genus levels, respectively. Pyroligneous acid reduced the relative abundance of Bacteria and Firmicutes and increased that of Lactobacillus. The detected ARGs belonged to 36 drug classes, including mainly macrolides, tetracycline, lincosamides, and phenicol. These types of ARGs decreased during fermentation and were further reduced by PA. These types of ARGs were positively correlated (P < 0.05) with fermentation parameters like pH value and ammonia-N content and with bacterial communities. At the genus level, the top several drug classes, including macrolide, tetracycline, lincosamide, phenicol, oxazolidinone, streptogramin, pleuromutilin, and glycopeptide, were positively correlated with Staphylococcus, Streptococcus, Listeria, Bacillus, Klebsiella, Clostridium, and Enterobacter, the potential hosts of ARGs. Overall, ARGs in alfalfa silage were abundant and were influenced by the fermentation parameters and microbial community composition. Ensiling could be a feasible way to mitigate ARGs in forages. The addition of PA could not only improve fermentation quality but also reduce ARG pollution of alfalfa silage. IMPORTANCE Antibiotic resistance genes (ARGs) are considered environmental pollutants posing a potential human health risk. Silage is an important and traditional feed, mainly for ruminants. ARGs in silages might influence the diversity and distribution of ARGs in animal intestinal and feces and then the manure and the manured soil. However, the diversity and dynamics of ARGs in silage during fermentation are still unknown. We ensiled alfalfa, one of the most widely used forages, with or without pyroligneous acid (PA), which was proved to have the ability to reduce ARGs in soils. The results showed that ARGs in alfalfa silage were abundant and were influenced by the fermentation parameters and microbial community. The majority of ARGs in alfalfa silage reduced during fermentation. The addition of PA could improve silage quality and reduce ARG pollution in alfalfa silage. This study can provide useful information for understanding and controlling ARG pollution in animal production.202235862964
812660.9826Antiallergic drugs drive the alteration of microbial community and antibiotic resistome in surface waters: A metagenomic perspective. Antiallergic drugs (AADs) are emerging contaminants of global concern due to their environmental persistence and potential ecological impacts. This study investigated the effects of seven AADs (chlorpheniramine, diphenhydramine, cetirizine, loratadine, desloratadine, sodium cromoglicate and calcium gluconate) at environmentally relevant concentrations on antibiotic resistome and bacterial community structures in water using microcosm experiments and metagenomic sequencing. The results showed that AADs increased the abundance of antibiotic-resistant bacteria (ARB) by 1.24- to 7.78-fold. Community structure shifts indicated that chlorpheniramine, diphenhydramine, and cetirizine promoted Actinobacteria (e.g., Aurantimicrobium), while the other four AADs favored Proteobacteria (e.g., Limnohabitans). AADs also significantly altered the relative abundance of antibiotic resistance genes (ARGs), with Actinobacteria and Proteobacteria identified as key ARB components and potential hosts of ARGs (e.g., evgS, mtrA, RanA). Host analysis showed ARGs were primarily carried by Actinobacteria (e.g., Aurantimicrobium) under chlorpheniramine, diphenhydramine, and cetirizine exposure, but by Proteobacteria (e.g., Limnohabitans) under the other four AADs. Furthermore, AADs facilitated the horizontal transfer of ARGs (e.g., evgS) within microbial communities, contributing to antibiotic resistance dissemination. This study highlights the ecological risks of AADs in promoting antibiotic resistance spread and provides new insights into their impact on microbial communities and resistome dynamics in aquatic environments.202540570627
690770.9825Deciphering the impact of organic loading rate and digestate recirculation on the occurrence patterns of antibiotics and antibiotic resistance genes in dry anaerobic digestion of kitchen waste. Organic loading rate (OLR) is crucial for determining the stability of dry anaerobic digestion (AD). Digestate recirculation contributes to reactor stability and enhances methane production. Nevertheless, the understanding of how OLR and digestate recirculation affect the abundance and diversity of antibiotics and antibiotic resistance genes (ARGs), as well as the mechanisms involved in the dissemination of ARGs, remains limited. This study thoroughly investigated this critical issue through a long-term pilot-scale experiment. The metabolome analyses revealed the enrichment of various antibiotics, such as aminoglycoside, tetracycline, and macrolide, under low OLR conditions (OLR ≤ 4.0 g·VS/L·d) and the reactor instability. Antibiotics abundance decreased by approximately 19.66-31.69 % during high OLR operation (OLR ≥ 6.0 g·VS/L·d) with digestate recirculation. The metagenome analyses demonstrated that although low OLR promoted reactor stability, it facilitated the proliferation of antibiotic-resistant bacteria, such as Pseudomonas, and triggered functional profiles related to ATP generation, oxidative stress response, EPS secretion, and cell membrane permeability, thereby facilitating horizontal gene transfer (HGT) of ARGs. However, under stable operation at an OLR of 6.0 g·VS/L·d, there was a decrease in ARGs abundance but a notable increase in human pathogenic bacteria (HPB) and mobile genetic elements (MGEs). Subsequently, during reactor instability, the abundance of ARGs and HPB increased. Notably, during digestate recirculation at OLR levels of 6.0 and 7.0 g·VS/L·d, the process attenuated the risk of ARGs spread by reducing the diversity of ARGs hosts, minimizing interactions among ARGs hosts, ARGs, and MGEs, and weakening functional profiles associated with HGT of ARGs. Overall, digestate recirculation aids in reducing the abundance of antibiotics and ARGs under high OLR conditions. These findings provide advanced insights into how OLR and digestate recirculation affect the occurrence patterns of antibiotics and ARGs in dry AD.202438968733
693480.9824Impact of protist predation on bacterial community traits in river sediments. Sediment-associated microbial communities are pivotal in driving biogeochemical processes and serve as key indicators of ecosystem health and function. However, the ecological impact of protist predation on these microbial communities remains poorly understood. Here, sediment microcosms were established with varying concentrations of indigenous protists. Results revealed that protist predation exerted strong and differential effects on the bacterial community composition, functional capabilities, and antibiotic resistance profiles. Higher levels of protist predation pressure increased bacterial alpha diversity and relative abundance of genera associated with carbon and nitrogen cycling, such as Fusibacter, Methyloversatilis, Azospirillum, and Holophaga. KEGG analysis indicated that protist predation stimulated microbial processes related to the carbon, nitrogen, and sulfur cycles. Notably, the relative abundance and associated health risks of antibiotic resistance genes (ARGs), virulence factor genes (VFGs), and mobile genetic elements (MGEs) were affected by predation pressure. Medium protist predation pressure increased the relative abundance and potential risks associated with ARGs, whereas high protist concentrations led to a reduction in both, likely due to a decrease in the relative abundance of ARG-hosting pathogenic bacteria such as Pseudomonas, Acinetobacter, and Aeromonas. These findings provide comprehensive insights into the dynamics of bacterial communities under protist predation in river sediment ecosystems.202540885182
811990.9824Biochar-amended composting of lincomycin fermentation dregs promoted microbial metabolism and reduced antibiotic resistance genes. Improper disposal of antibiotic fermentation dregs poses a risk of releasing antibiotics and antibiotic resistant bacteria to the environment. Therefore, this study evaluated the effects of biochar addition to lincomycin fermentation dregs (LFDs) composting. Biochar increased compost temperature and enhanced organic matter decomposition and residual antibiotics removal. Moreover, a 1.5- to 17.0-fold reduction in antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) was observed. Adding biochar also reduced the abundances of persistent ARGs hosts (e.g., Streptomyces, Pseudomonas) and ARG-related metabolic pathways and genes (e.g., ATP-binding cassette type-2 transport, signal transduction and multidrug efflux pump genes). By contrast, compost decomposition improved due to enhanced metabolism of carbohydrates and amino acids. Overall, adding biochar into LFDs compost reduced the proliferation of ARGs and enhanced microbial community metabolism. These results demonstrate that adding biochar to LFDs compost is a simple and efficient way to decrease risks associated with LFDs composting.202336334868
8120100.9823Insight into the fate of antibiotic resistance genes and bacterial community in co-composting green tea residues with swine manure. Green tea residues (GTRs) are byproducts of tea production and processing, and this type of agricultural waste retains nutritious components. This study investigated the co-composting of GTRs with swine manure, as well as the effects of GTRs on antibiotic resistance genes (ARGs) and the bacterial community during co-composting. The temperature and C/N ratio indicate compost was mature after processing. The addition of GTRs effectively promoted the reduction in the abundances of most targeted ARGs (tet and sul genes), mobile genetic element (MGE; intI1), and metal resistance genes (MRGs; pcoA and tcrB). Redundancy analysis (RDA) showed that GTRs can reduce the abundance of MRGs and ARGs by reducing the bioavailability of heavy metals. Network analysis shows that Firmicutes and Actinobacteria were the main hosts of ARGs and ARGs, MGEs, and MRGs shared the same potential host bacteria. Adding GTRs during composting may reduce ARGs transmission through horizontal gene transfer (HGT). GTRs affected the bacterial community, thereby influencing the variations in the ARG profiles and reducing the potential risk associated with the compost product.202032310121
7004110.9823Sheep and rapeseed cake manure promote antibiotic resistome in agricultural soil. The application of manure in agriculture caused the emergence and spread of antibiotic resistance genes (ARGs) and antibiotic-resistant bacteria (ARB) in soil environments. However, the co-occurrence pattern and host diversity of ARGs and MGEs in soils amended with animal and green manures remains unclear. In this study, metagenomic assembly and binning techniques were employed to comprehensively explore the effects of sheep manure and green manure on soil microbiome, antibiotic resistomes, and ARG hosts. Both rapeseed cake manure and sheep manure increased the abundance and diversity of ARGs, with sheep manure particularly enhancing the abundance of ARGs conferring resistant to multidrug, quinolone, rifampicin, and macrolide-lincosamide-streptogramin (MLSB). Mobile genetic elements (MGEs), such as plasmids, transposases, and integrases, preferentially enhanced the potential mobility of some ARGs subtypes (i.e. sul2, aadA, qacH, and folp), facilitating the spread of ARGs. Additionally, sheep manure reshaped the bacterial community structure and composition as well as ARG hosts, some opportunistic pathogens (i.e. Staphylococcus, Streptococcus, and Pantoea) acquired antibiotic resistance and remained recalcitrant. It is concluded that rapeseed cake manure and sheep manure increased the co-occurrence of ARGs and MGEs, enriched the potential ARG hosts, and promoted the dissemination of ARGs in agricultural soils.202540633350
8118120.9822Effects of biocontrol Bacillus and fermentation bacteria additions on the microbial community, functions and antibiotic resistance genes of prickly ash seed oil meal-biochar compost. This study evaluated the effects of biocontrol Bacillus and fermenting bacteria addition on the microbial community, metabolic functions and antibiotic resistance genes (ARGs) of new prickly ash seed oil meal (PSOM)-biochar composting. The results showed that the addition of Bacillus subtilis and fermentation bacteria significantly increased the NH(4)(+)-N, bacterial abundance and fungal diversity of compost while decreasing the relative abundances (RAs) of carbon metabolism genes in mature compost. NH(4)(+)-N was significantly correlated with microbial abundance and diversity, and its increase was closely related to microbial amino acid metabolism. The addition of biocontrol and fermenting bacteria changed the RAs of ARGs, which was caused by changes in the potential hosts Proteobacteria, Bacteroidota and Firmicutes in the compost. Consequently, adding Bacillus and fermenting bacteria into PSOM to make composting was suggested as an effective method to promote nutrient transformation, regulate microbial activity and decrease RAs of tetracycline and vancomycin ARGs.202134339999
6919130.9822Enhanced removal of antibiotic resistance genes during chicken manure composting after combined inoculation of Bacillus subtilis with biochar. This study explored the combined effects of Bacillus subtilis inoculation with biochar on the evolution of bacterial communities, antibiotic resistance genes (ARGs), and mobile genetic elements (MGEs) during the composting of chicken manure. The results showed that B. subtilis inoculation combined with biochar increased bacterial abundance and diversity as well as prolonged the compost thermophilic period. Promoted organic matter biodegradation and facilitated the organic waste compost humification process, reduced the proliferation of ARGs by altering the bacterial composition. Firmicutes and Actinobacteriota were the main resistant bacteria related to ARGs and MGEs. The decrease in ARGs and MGEs was associated with the reduction in the abundance of related host bacteria. Compost inoculation with B. subtilis and the addition of biochar could promote nutrient transformation, reduce the increase in ARGs and MGEs, and increase the abundance of beneficial soil taxa.202437778803
7873140.9820Wheat straw pyrochar more efficiently decreased enantioselective uptake of dinotefuran by lettuce and dissemination of antibiotic resistance genes than hydrochar in an agricultural soil. Remediation of soils pollution caused by dinotefuran, a chiral pesticide, is indispensable for ensuring human food security. In comparison with pyrochar, the effect of hydrochar on enantioselective fate of dinotefuran, and antibiotic resistance genes (ARGs) profiles in the contaminated soils remain poorly understood. Therefore, wheat straw hydrochar (SHC) and pyrochar (SPC) were prepared at 220 and 500 °C, respectively, to investigate their effects and underlying mechanisms on enantioselective fate of dinotefuran enantiomers and metabolites, and soil ARG abundance in soil-plant ecosystems using a 30-day pot experiment planted with lettuce. SPC showed a greater reduction effect on the accumulation of R- and S-dinotefuran and metabolites in lettuce shoots than SHC. This was mainly resulted from the lowered soil bioavailability of R- and S-dinotefuran due to adsorption/immobilization by chars, together with the char-enhanced pesticide-degrading bacteria resulted from increased soil pH and organic matter content. Both SPC and SHC efficiently reduced ARG levels in soils, owing to lowered abundance of ARG-carrying bacteria and declined horizontal gene transfer induced by decreased dinotefuran bioavailability. The above results provide new insights for optimizing char-based sustainable technologies to mitigate pollution of dinotefuran and spread of ARGs in agroecosystems.202336996986
6915150.9820Industrial-scale aerobic composting of livestock manures with the addition of biochar: Variation of bacterial community and antibiotic resistance genes caused by various composting stages. The presence of large amounts of antibiotic resistance genes (ARGs) in livestock manures poses an impending, tough safety risk to ecosystems. To investigate more comprehensively the mechanisms of ARGs removal from industrial-scale composting of livestock manure based on biochar addition, we tracked the dynamics of bacterial community and ARGs at various stages of aerobic composting of livestock manures with 10% biochar. There were no significant effects of biochar on the bacterial community and the profiles of ARGs. During aerobic composting, the relative abundance of ARGs and mobile genetic elements (MGEs) showed overall trends of decreasing and then increasing. The key factor driving the dynamics of ARGs was bacterial community composition, and the potential hosts of ARGs were Caldicoprobacter, Tepidimicrobium, Ignatzschineria, Pseudogracilibacillus, Actinomadura, Flavobacterium and Planifilum. The retention of the thermophilic bacteria and the repopulation of the initial bacteria were the dominant reasons for the increase in ARGs at maturation stage. Additionally, among the MGEs, the relative abundance of transposon gene was substantially removed, while the integron genes remained at high relative abundance. Our results highlighted that the suitability of biochar addition to industrial-scale aerobic composting needs to be further explored and that effective measures are needed to prevent the increase of ARGs content on maturation stage.202236162559
6912160.9820Regulation of antibiotic resistance gene rebound by degrees of microecological niche occupation by microbiota carried in additives during the later phases of swine manure composting. The occupation of microecological niches (MNs) by bacteria carrying lower antibiotic resistance genes (ARGs) has been demonstrated an effective strategy for reducing ARGs in compost, thereby mitigating the associated land use risks. In this study, humus soil (HS), matured compost (MC), and their respective isolated microbial agents (HSM and MCM), which exhibit varying abundances of ARGs, were introduced as additives after the thermophilic phase to investigate their influence on ARG removal and the mechanisms underlying effective MN occupation. The addition of HS resulted in the most favorable outcomes, including the highest carbon degradation, minimized nitrogen loss, and an 83.16 % reduction in ARG abundance during the later composting stages. In comparison, ARG rebound levels were 61.77 %-285.33 % across other treatments and 729.23 % in the control. Distinct dominant bacterial genera and potential ARG-host bacterial communities were observed, which varied with different additives and contributed to MN occupation dynamics. The addition of the HS additive intensified competition among non-host bacteria, and diversified the interactions both between genes and between bacteria. These changes suppressed horizontal gene transfer (HGT) mediated by mobile genetic elements (MGEs) and altered the abundance and composition of both dominant and non-dominant potential host species. Furthermore, it shifted the relative importance of key physicochemical parameters, collectively enhancing ARG removal during composting. These findings elucidate the mechanisms by which MN adjustments contribute to ARG reduction, providing actionable insights for designing composting strategies that mitigate environmental ARG dissemination risks more effectively.202540154224
6933170.9819Enantioselective effect of the chiral fungicide tebuconazole on the microbiota community and antibiotic resistance genes in the soil and earthworm gut. Tebuconazole, consisting of two enantiomers, has a high detectable rate in the soil. The residue of tebuconazole in the soil may cause risk to microbiota community. Antibiotic resistance genes (ARGs) are considered as emerging environmental contaminants, and they can be transferred vertically and horizontally between microbiota community in the soil. Until now, the enantioselective effect of tebuconazole on the microbiota community and ARGs in the soil and earthworm gut has remained largely unknown. Tebuconazole enantiomers showed different bioconcentration behaviors in earthworms. The relative abundances of bacteria belonging to Actinobacteriota, Crenarchaeota and Chloroflexi in R-(-)-tebuconazole-treated soil were higher than those in S-(+)-tebuconazole-treated soil at same concentrations. In the earthworm gut, bacteria belonging to Proteobacteria and Bacteroidota exhibited different relative abundances between the S-(+)-tebuconazole and R-(-)-tebuconazole treatments. The numbers and abundances of ARGs in the soil treated with fungicides were higher than those in the control. In earthworm gut, the diversities of ARGs in all treatments were higher than that in the control, and the relative abundances of Aminoglycoside, Chloramphenicol, Multidrug resistance genes and mobile genetic elements (MGEs) in R-(-)-tebuconazole-treated earthworm gut were higher than those in S-(+)-tebuconazole-treated earthworm gut. Most of ARGs showed a significantly positive correlation with MGEs. Based on network analysis, many ARGs may be carried by bacteria belonging to Bacteroidota and Proteobacteria. These results provide valuable information for understanding the enantioselective effect of tebuconazole on the microbiota community and ARGs.202337422227
8581180.9819Tire particles and its leachates: Impact on antibiotic resistance genes in coastal sediments. Tire particles (TPs), a significant group of microplastics, can be discharged into the coastal environments in various ways. However, our understanding of how TPs impact the antibiotic resistance and pathogenic risks of microorganisms in coastal sediments remains limited. In this study, we used metagenomics to investigate how TPs and their leachates could affect the prevalence of antibiotic resistance genes (ARGs), virulence factor genes (VFGs), and their potential risks to the living creatures such as soil invertebrates and microorganisms in the coastal sediments. We discovered that TP addition significantly increased the abundance and diversity of ARGs and VFGs in coastal sediments, with raw TPs displayed higher impacts than TP leachates and TPs after leaching on ARGs and VFGs. With increasing TP exposure concentrations, the co-occurrence frequency of ARGs and mobile genetic elements (MGEs) in the same contig also increased, suggesting that TPs could enhance the dispersal risk of ARGs. Our metagenome-based binning analysis further revealed that exposure to TPs increased the abundance of potentially pathogenic antibiotic-resistant bacteria (PARB). In addition, chemical additives of TP leachates (e.g., Zn and N-cyclohexylformamide) significantly affected the changes of ARGs in the pore water. In summary, our study provides novel insights into the adverse effects of TP pollutions on aggravating the dissemination and pathogenic risks of ARGs and PARB in the coastal environment.202438147751
8123190.9819The effect of bulk-biochar and nano-biochar amendment on the removal of antibiotic resistance genes in microplastic contaminated soil. Biochar amendment has significant benefits in removing antibiotic resistance genes (ARGs) in the soil. Nevertheless, there is little information on ARGs removal in microplastic contaminated soil. Herein, a 42-day soil microcosm experiment were carried out to study how two coconut shell biochars (bulk- and nano-size) eliminate soil ARGs with/without microplastic presence. The results showed that microplastic increased significantly the numbers and abundances of ARGs in soil at 14d of cultivation. And, two biochars amendment effectively inhibited soil ARGs spread whether or not microplastic was present, especially for nano-biochar which had more effective removal compared to bulk-biochar. However, microplastic weakened soil ARGs removal after applying same biochar. Two biochars removed ARGs through decreasing horizontal gene transfer (HGT) of ARGs, potential host-bacteria abundances, some bacteria crowding the eco-niche of hosts and promoting soil properties. The adverse effect of microplastic on ARGs removal was mainly caused by weakening mobile genetic elements (MGEs) removal, and by changing soil properties. Structural equation modeling (SEM) analysis indicated that biochar's effect on ARGs profile was changed by its size and microplastic presence through altering MGEs abundances. These results highlight that biochar amendment is still an effective method for ARGs removal in microplastic contaminated soil.202437907163