Repercussions of Prolonged Pesticide Use on Natural Soil Microbiome Dynamics Using Metagenomics Approach. - Related Documents




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865101.0000Repercussions of Prolonged Pesticide Use on Natural Soil Microbiome Dynamics Using Metagenomics Approach. The residual pesticides in soil can affect the natural microbiome composition and genetic profile that drive nutrient cycling and soil fertility. In the present study, metagenomic approach was leveraged to determine modulations in nutrient cycling and microbial composition along with connected nexus of pesticide, antibiotic, and heavy metal resistance in selected crop and fallow soils having history of consistent pesticide applications. GC-MS analysis estimated residuals of chlorpyrifos, hexachlorbenzene, and dieldrin showing persistent nature of pesticides that pose selective pressure for microbial adaptation. Taxonomic profiling showed increased abundance of pesticide degrading Streptomyces, Xanthomonas, Cupriavidus, and Pseudomonas across the selected soils. Genes encoding for pesticide degrading cytochrome p450, organophosphorus hydrolase, aldehyde dehydrogenase, and oxidase were predominant and positively correlated with Bacillus, Sphingobium, and Burkholderia. Nitrogen-fixing genes (nifH, narB, and nir) were relatively less abundant in crop soils, correlating to the decrease in nitrogen-fixing bacteria (Anabaena, Pantoea, and Azotobacter). Microbial enzymes involved in carbon (pfkA, gap, pgi, and tpiA) and phosphorus cycle (gmbh and phnJ) were significantly higher in crop soils indicating extensive utilization of pesticide residuals as a nutrient source by the indigenous soil microbiota. Additionally, presence of antibiotic and heavy metal resistance genes suggested potential cross-resistance under pressure from pesticide residues. The results implied selective increase in pesticide degrading microbes with decrease in beneficial bacteria that resulted in reduced soil health and fertility. The assessment of agricultural soil microbial profile will provide a framework to develop sustainable agriculture practices to conserve soil health and fertility.202539096471
864610.9995A Degeneration Gradient of Poplar Trees Contributes to the Taxonomic, Functional, and Resistome Diversity of Bacterial Communities in Rhizosphere Soils. Bacterial communities associated with roots influence the health and nutrition of the host plant. However, the microbiome discrepancy are not well understood under different healthy conditions. Here, we tested the hypothesis that rhizosphere soil microbial diversity and function varies along a degeneration gradient of poplar, with a focus on plant growth promoting bacteria (PGPB) and antibiotic resistance genes. Comprehensive metagenomic analysis including taxonomic investigation, functional detection, and ARG (antibiotics resistance genes) annotation revealed that available potassium (AK) was correlated with microbial diversity and function. We proposed several microbes, Bradyrhizobium, Sphingomonas, Mesorhizobium, Nocardioides, Variovorax, Gemmatimonadetes, Rhizobacter, Pedosphaera, Candidatus Solibacter, Acidobacterium, and Phenylobacterium, as candidates to reflect the soil fertility and the plant health. The highest abundance of multidrug resistance genes and the four mainly microbial resistance mechanisms (antibiotic efflux, antibiotic target protection, antibiotic target alteration, and antibiotic target replacement) in healthy poplar rhizosphere, corroborated the relationship between soil fertility and microbial activity. This result suggested that healthy rhizosphere soil harbored microbes with a higher capacity and had more complex microbial interaction network to promote plant growing and reduce intracellular levels of antibiotics. Our findings suggested a correlation between the plant degeneration gradient and bacterial communities, and provided insight into the role of high-turnover microbial communities as well as potential PGPB as real-time indicators of forestry soil quality, and demonstrated the inner interaction contributed by the bacterial communities.202133810508
864520.9994Resilience mechanisms of rhizosphere microorganisms in lead-zinc tailings: Metagenomic insights into heavy metal resistance. This study investigates the impact of heavy metal contamination in lead-zinc tailings on plant and soil microbial communities, focusing on the resilience mechanisms of rhizosphere microorganisms in these extreme environments. Utilizing metagenomic techniques, we identified a significant association between Coriaria nepalensis Wall. rhizosphere microbial communities and metal(loid) resistance genes. Our results reveal a notable diversity and abundance of bacteria within the rhizosphere of tailings, primarily consisting of Proteobacteria, Actinobacteria, and Chloroflexi. The presence of metal-resistant bacterial taxa, including Afipia, Bradyrhizobium, Sphingomonas, and Miltoncostaea, indicates specific evolutionary adaptations to metal-rich, nutrient-deficient environments. Elevated expression of resistance genes such as znuD, zntA, pbrB, and pbrT underscores the microorganisms' ability to endure these harsh conditions. These resistance genes are crucial for maintaining biodiversity, ecosystem stability, and adaptability. Our findings enhance the understanding of interactions between heavy metal contamination, microbial community structure, and resistance gene dynamics in lead-zinc tailings. Additionally, this research provides a theoretical and practical foundation for employing plant-microbial synergies in the in-situ remediation of contaminated sites.202540056745
856830.9993Bioremediation potential of sulfadiazine-degrading bacteria: Impacts on ryegrass growth and soil functionality. The extensive use of antibiotics, particularly sulfadiazine (SDZ), has led to significant environmental contamination and the proliferation of antibiotic resistance genes (ARGs). This study investigates the bioremediation potential of two SDZ-degrading bacterial strains, Acinetobacter sp. M9 and Enterobacter sp. H1, and their impact on ryegrass (Lolium perenne) growth and the inter-root microenvironment in SDZ-contaminated soils. A pot experiment combined with amplicon and metagenomic sequencing revealed that inoculation with M9 and H1 significantly enhanced ryegrass growth by alleviating oxidative stress, increasing chlorophyll content, and improving soil nutrient availability. The strains also promoted SDZ degradation efficiency and improved carbon and nitrogen cycling through the upregulation of key functional genes. Furthermore, microbial community analysis demonstrated increased alpha diversity, shifts in dominant taxa, and functional enrichment in pollutant degradation pathways. The dynamics of ARGs revealed a decrease in aminoglycoside, rifamycin, and streptomycin resistance genes, while sulfonamide resistance genes increased due to the residual SDZ stress. These findings highlight the potential of M9 and H1 as sustainable bioremediation agents to mitigate antibiotic contamination, improve soil health, and support plant growth in polluted environments.202540122011
752340.9993Transfer of antibiotic resistance genes from soil to wheat: Role of host bacteria, impact on seed-derived bacteria, and affecting factors. The transfer of antibiotic resistance genes (ARGs) from soils to plants is poorly understood, especially the role of host bacteria in soils and its impact on seed-derived bacteria. Wheat (Triticum aestivum L.) was thus used to fill the gap by conducting pot experiments, with target ARGs and bacterial community analyzed. Results showed that the relative abundances of target ARGs gradually decreased during transfer of ARGs from the rhizosphere soil to root and shoot. Host bacteria in the rhizosphere soil were the primary source of ARGs in wheat. The 38, 21, and 19 potential host bacterial genera of target ARGs and intI1 in the rhizosphere soil, root, and shoot were identified, respectively, and they mainly belonged to phylum Proteobacteria. The abundance of ARGs carried by pathogenic Corynebacterium was reduced in sequence. During transfer of ARGs from the rhizosphere soil to root and shoot, some seed-derived bacteria and pathogenic Acinetobacter obtained ARGs through horizontal gene transfer and became potential host bacteria. Furthermore, total organic carbon, available nitrogen of the rhizosphere soil, water use efficiency, vapor pressure deficit, and superoxide dismutase of plants were identified as the key factors affecting potential host bacteria transfer in soils to wheat. This work provides important insights into transfer of ARGs and deepens our understanding of potential health risks of ARGs from soils to plants.202337741386
696450.9993Metagenomic approach reveals the role of bioagents in the environmental dissemination risk of rhizosphere soil antibiotic resistance genes pollution. Antibiotic resistance genes (ARGs) have been identified as emerging contaminants, raising concerns around the world. As environmentally friendly bioagents (BA), plant growth-promoting rhizobacteria (PGPR) have been used in agricultural systems. The introduction of BA will lead to the turnover of the microbial communities structure. Nevertheless, it is still unclear how the colonization of the invaded microorganisms could affects the rhizosphere resistome. Consequently, 190 ARGs and 25 integrative and conjugative elements (ICEs) were annotated using the metagenomic approach in 18 samples from the Solanaceae crop rhizosphere soil under BA and conventional treatment (CK) groups. Our study found that, after 90 days of treatment, ARG abundance was lower in the CK group than in the BA group. The results showed that aminoglycoside antibiotic resistance (OprZ), phenicol antibiotic resistance (OprN), aminoglycoside antibiotic resistance (ceoA/B), aminocoumarin antibiotic resistance (mdtB) and phenicol antibiotic resistance (MexW) syntenic with ICEs. Moreover, in 11 sequences, OprN (phenicol antibiotic resistance) was observed to have synteny with ICEPaeLESB58-1, indicating that the ICEs could contribute to the spread of ARGs. Additionally, the binning result showed that the potential bacterial hosts of the ARGs were beneficial bacteria which could promote the nutrition cycle, such as Haliangium, Nitrospira, Sideroxydans, Burkholderia, etc, suggesting that bacterial hosts have a great influence on ARG profiles. According to the findings, considering the dissemination of ARGs, BA should be applied with caution, especially the use of beneficial bacteria in BA. In a nutshell, this study offers valuable insights into ARGs pollution control from the perspective of the development and application of BA, to make effective strategies for blocking pollution risk migration in the ecological environment.202439374754
864960.9993Antibiotic-Induced Recruitment of Specific Algae-Associated Microbiome Enhances the Adaptability of Chlorella vulgaris to Antibiotic Stress and Incidence of Antibiotic Resistance. Insights into the symbiotic relation between eukaryotic hosts and their microbiome lift the curtain on the crucial roles of microbes in host fitness, behavior, and ecology. However, it remains unclear whether and how abiotic stress shapes the microbiome and further affects host adaptability. This study first investigated the effect of antibiotic exposure on behavior across varying algae taxa at the community level. Chlorophyta, in particular Chlorella vulgaris, exhibited remarkable adaptability to antibiotic stress, leading to their dominance in phytoplankton communities. Accordingly, we isolated C. vulgaris strains and compared the growth of axenic and nonaxenic ones under antibiotic conditions. The positive roles of antibiotics in algal growth were apparent only in the presence of bacteria. Results of 16S rRNA sequencing further revealed that antibiotic challenges resulted in the recruitment of specific bacterial consortia in the phycosphere, whose functions were tightly linked to the host growth promotion and adaptability enhancement. In addition, the algal phycosphere was characterized with 47-fold higher enrichment capability of antibiotic resistance genes (ARGs) than the surrounding water. Under antibiotic stress, specific ARG profiles were recruited in C. vulgaris phycosphere, presumably driven by the specific assembly of bacterial consortia and mobile genetic elements induced by antibiotics. Moreover, the antibiotics even enhanced the dissemination potential of the bacteria carrying ARGs from the algal phycosphere to broader environmental niches. Overall, this study provides an in-depth understanding into the potential functional significance of antibiotic-mediated recruitment of specific algae-associated bacteria for algae adaptability and ARG proliferation in antibiotic-polluted waters.202337642958
696070.9993Effortless rule: Effects of oversized microplastic management on lettuce growth and the dynamics of antibiotic resistance genes from fertilization to harvest. The complexity of soil microplastic pollution has driven deeper exploration of waste management strategies to evaluate environmental impact. This study introduced oversized microplastics (OMPs, 1-5 mm) during membrane composting to produce organic fertilizers, and conducted a 2 × 2 pot experiment: exogenous OMPs were added when normal fertilizer (no OMPs intervention) was applied, while artificial removal of OMPs was implemented when contaminated fertilizer (with OMPs) was used. The study assessed the effects of these management strategies on lettuce growth, soil environments, and potential biological safety risks related to the spread and expression of high-risk antibiotic resistance genes (ARGs) in humans. Results showed that both exogenous OMPs addition and removal negatively affected plant height and harvest index, with shifts in the rhizosphere microbial community identified as a key factor rather than soil nutrients. Exogenous OMPs altered rhizosphere and endophytic microbial communities, and plant growth-promoting bacteria were transferred to the surface of OMPs from rhizosphere soil. In contrast, bacteria such as Truepera, Pseudomonas, and Streptomyces in compost-derived OMPs supported lettuce growth, and their removal negated these effects. Some endophytic bacteria may promote growth but pose public health risks when transmitted through the food chain. OMPs in composting or planting significantly enhanced the expression of target ARGs in lettuce, particularly bla(TEM). However, simulated digestion results indicated that OMPs reduced the expression of six key ARGs, including bla(TEM), among the ten critical target ARGs identified in this context. Notably, the removal management strategies raised five of them posing potential risks from lettuce consumption. This study highlights that both introducing and removing OMPs may pose ecological and food safety risks, emphasizing the need for optimized organic waste management strategies to mitigate potential health hazards.202540157188
693080.9993Effect of fertilizer type on antibiotic resistance genes by reshaping the bacterial community and soil properties. Conventional and bio-organic fertilizers play an important role in maintaining soil health and promoting crop growth. However, the effect of organic fertilizers on the prevalence of antibiotic resistance genes (ARGs) in the vegetable cropping system has been largely overlooked. In this study, we investigated the impacts of soil properties and biotic factors on ARG profiles by analyzing ARG and bacterial communities in vegetable copping soils with a long-term history of manure and bio-organic fertilizer application. The ARG abundance in the soil was significantly increased by 116% with manure application compared to synthetic NPK fertilizer application. This finding was corroborated by our meta-analysis that the longer the duration of manure application, the greater the response of increased soil ARG abundance. However, bio-organic fertilizers containing Trichoderma spp. Significantly reduced ARG contamination by 31% compared to manure application. About half of the ARG variation was explained by changes in bacterial abundance and structure, followed by soil properties. The mitigation of ARG by Trichoderma spp. Is achieved by altering the structure of the bacterial community and weakening the close association between bacteria and ARG prevalence. Taken together, these findings shed light on the contribution of bio-organic fertilizers in mitigating ARG contamination in agricultural soils, which can help manage the ecological risk posed by ARG inputs associated with manure application.202337343633
756290.9993Nanoparticles and antibiotics stress proliferated antibiotic resistance genes in microalgae-bacteria symbiotic systems. The comprehensive effect of exogenous pollutants on the dispersal and abundance of antibiotic-resistance genes (ARGs) in the phycosphere, bacterial community and algae-bacteria interaction remains poorly understood. We investigated community structure and abundance of ARGs in free-living (FL) and particle-attached (PA) bacteria in the phycosphere under nanoparticles (silver nanoparticles (AgNPs) and hematite nanoparticles (HemNPs)) and antibiotics (tetracycline and sulfadiazine) stress using high-throughput sequencing and real-time quantitative PCR. Meanwhile, the intrinsic connection of algae-bacteria interaction was explored by transcriptome and metabolome. The results showed that the relative abundance of sulfonamide and tetracycline ARGs in PA and FL bacteria increased 103-129 % and 112-134 %, respectively, under combined stress of nanoparticles and antibiotics. Antibiotics have a greater effect on ARGs than nanoparticles at environmentally relevant concentrations. Proteobacteria, Firmicutes, and Bacteroidetes, as the primary potential hosts of ARGs, were the dominant phyla. Lifestyle, i.e., PA and FL, significantly determined the abundance of ARGs and bacterial communities. Moreover, algae can provide bacteria with nutrients (carbohydrates and amino acids), and can also produce antibacterial substances (fatty acids). This algal-bacterial interaction may indirectly affect the distribution and abundance of ARGs. These findings provide new insights into the distribution and dispersal of ARGs in microalgae-bacteria symbiotic systems.202336283215
6931100.9993What role does organic fertilizer actually play in the fate of antibiotic resistome and pathogenic bacteria in planting soil? Organic fertilizer increase antibiotic resistance genes (ARGs) and bacterial pathogens have widely documented. However, how organic fertilizer is involved in changing soil ARGs and pathogenic bacteria after long-term (≥5 years) application remains unclear. Herein, the ARGs and pathogenic bacteria were compared in organic fertilized soils (AF) and non-fertilized soils (NF), and the contribution of input sources (organic fertilizer, irrigation water, air and background soil) on soil ARGs also was determined in this study. Results showed that the abundances of some ARGs, such as vanR and aac(6')-I in AF, were significantly higher than these of NF (p < 0.05). And a relatively higher abundance of potential pathogens, especially, Salmonella enterica and Stenotrophomonas maltophilia, in AF was observed. This indicated that organic fertilizer application can maintain a high level of some soil ARGs and pathogenic bacteria for at least 5 years. Traceability analysis unearthed that organic fertilizer application mainly increased its own contribution to soil ARGs from 1.16% to 9.05%, as well reduced the contribution of background soil, suggesting that the increase in soil ARGs may be partly attributable to organic fertilizer inputs. Notably, organic fertilizer application did not significantly alter the contribution ratio of input sources to microorganisms, but there was a clear change in the composition of soil microorganisms, which meant that the effect of the input source on the microorganism may emanate from other factors, rather than direct inputs. Subsequent structural equation demonstrated that organic fertilizer application significantly enhanced the effect of environmental factors on ARGs, and also indirectly increased the influence of communities on ARGs. Collectively, under the long-term fertilization, the role of organic fertilizers on soil ARGs not just stems from its own input, and also dominates the influence of environmental factors on ARGs. This study elucidates main causes for the difference in ARGs in AF vs. NF and enlightens actual role of organic fertilizer in them.202235623127
6985110.9993Elevated CO(2) Increased Antibiotic Resistomes in Seed Endophytes: Evidence from a Free-Air CO(2) Enrichment (FACE) Experiment. Climate warming affects antibiotic resistance genes (ARGs) in soil and the plant microbiome, including seed endophytes. Seeds act as vectors for ARG dissemination in the soil-plant system, but the impact of elevated CO(2) on seed resistomes remains poorly understood. Here, a free-air CO(2) enrichment system was used to examine the impact of elevated CO(2) on seed-associated ARGs and seed endophytic bacteria and fungi. Results indicated that elevated CO(2) levels significantly increased the relative abundance of seed ARGs and mobile genetic elements (MGEs), especially those related to beta-lactam resistance and MGEs. Increased CO(2) levels also influenced the composition of seed bacterial and fungal communities and the complexity of bacteria-fungi interactions. Fungi were more sensitive to changes in the CO(2) level than bacteria, with deterministic processes playing a greater role in fungal community assembly. Co-occurrence network analysis revealed a stronger correlation between fungi and ARGs compared to bacteria. The structure equation model (SEM) showed that elevated CO(2) directly influenced seed resistomes by altering bacterial composition and indirectly through bacteria-fungi interactions. Together, our work offers new insights into the effects of elevated CO(2) on antibiotic resistomes in the seed endosphere, highlighting their increased dissemination potential within soil-plant systems and the associated health risks in a changing environment.202439680930
7524120.9992Insights into the interactions of plant-associated bacteria and their role in the transfer of antibiotic resistance genes from soil to plant. This study discussed the role of plant-associated microbiome in regulating ARG transfer in soil-plant systems. Results showed that target ARGs in plants were mainly derived from rhizosphere soil. Cooperative interactions among bacteria in rhizosphere soil, plant-roots, plant-shoots, and soil-roots-shoots systems occurred during ARG transfer. The number of modules and keystone taxa identified as positively correlated with ARG transfer in rhizosphere soil, roots, and shoots was 3 and 49, 3 and 41, 2 and 5, respectively. Among these modules, module 3 in roots was significantly positively correlated with module 3 in rhizosphere soils and module 2 in shoots, indicating that module 3 in roots played central hub roles in ARG transfer from rhizosphere soil to roost and shoots. This may be because module 3 in roots increased cell motility and xenobiotics biodegradation and metabolism. These keystone taxa mainly belonged to Proteobacteria that can carry ARGs to transfer in soil-plant systems, especially Clostridium-sensu_stricito and Pseudomonas in rhizosphere soil carried ARGs into the shoot. Additionally, they promoted ARG transfer by increasing plant biomass, net photosynthetic rate and water use efficiency. The findings helped reveal the mechanism of plant-associated bacterial interactions and provided understanding for potential risks of ARG transfer from soil to plants.202439305593
8644130.9992Biotic and abiotic drivers of soil carbon, nitrogen and phosphorus and metal dynamic changes during spontaneous restoration of Pb-Zn mining wastelands. The biotic and abiotic mechanisms that drive important biogeochemical processes (carbon, nitrogen, phosphorus and metals dynamics) in metal mine revegetation remains elusive. Metagenomic sequencing was used to explored vegetation, soil properties, microbial communities, functional genes and their impacts on soil processes during vegetation restoration in a typical Pb-Zn mine. The results showed a clear niche differentiation between bacteria, fungi and archaea. Compared to bacteria and fungi, the archaea richness were more tightly coupled with natural restoration changes. The relative abundances of CAZyme-related, denitrification-related and metal resistance genes reduced, while nitrification, urease, inorganic phosphorus solubilisation, phosphorus transport, and phosphorus regulation -related genes increased. Redundancy analysis, hierarchical partitioning analysis, relative-importance analysis and partial least squares path modelling, indicated that archaea diversity, primarily influenced by available lead, directly impacts carbon dynamics. Functional genes, significantly affected by available cadmium, directly alter nitrogen dynamics. Additionally, pH affects phosphorus dynamics through changes in bacterial diversity, while metal dynamics are directly influenced by vegetation. These insights elucidate natural restoration mechanisms in mine and highlight the importance of archaea in soil processes.202540054196
7522140.9992Plants select antibiotic resistome in rhizosphere in early stage. Knowledge of the dissemination and emergence of antibiotic resistance genes (ARGs) in the plant rhizosphere is essential for evaluating the risk of the modern ARGs in soil planetary health. However, little is known about the selection mechanism in the plant rhizosphere. Here, we firstly analyzed the dynamic changes in the rhizosphere antibiotic resistome during the process of three passage enrichment of the rhizosphere microbiome in Arabidopsis thaliana (Col-0) and found evidence that plants directionally enriched levels of beneficial functional bacteria with many ARGs. Using the metagenome, we next evaluated the enrichment potential of the resistome in four common crops (barley, indica rice, japonica rice, and wheat) and found that the wheat rhizosphere harbored more abundant ARGs. Therefore, we finally cultivated the rhizosphere microbiome of wheat for three generations and found that approximately 60 % of ARGs were associated with beneficial bacteria enriched in the wheat rhizosphere, which might enter the soil food web and threaten human health, despite also performing beneficial functions in the plant rhizosphere. Our study provides new insights into the dissemination of ARGs in the plant rhizosphere, and the obtained data may be useful for sustainable and ecologically safe agricultural development.202336461576
7518150.9992Deciphering the toxic effects of metals in gold mining area: Microbial community tolerance mechanism and change of antibiotic resistance genes. Mine tailing dumps represent significant threats to ecological environments due to the presence of toxic substances. The present work investigated the relationship among microbial activity, the community, antibiotic resistance genes (ARGs) and trace metals in soil surrounding gold mine tailings. Using microbial metabolic activity and high-throughput sequencing analysis, we found the trace metals Cd and Hg could be main factors influencing the microbial community. According to bacterial co-occurrence pattern analysis, the effects of total cadmium and total mercury on bacterial diversity are potentially mediated by influencing bacteria community in the keystone module II. Additionally, most of metal-resistant bacteria belong to Actinobacteria and Proteobacteria, and the metal tolerance suggested to be linked with various functions including replication, recombination and repair, as well as inorganic ion transport and metabolism based on PICRUSt2 analysis. We also found that metals generated by mining activity may trigger the co-selection of antibiotic resistance in the phyla Actinobacteria and Proteobacteria due to co-resistance or cross resistance. Additionally, PLS-PM analysis revealed that metals could indirectly affect ARGs by influencing bacterial diversity in gold mining areas.202032678731
8569160.9992Indole-3-acetic acid-mediated root exudates as potential inhibitors of antibiotic resistance genes in the rhizosphere microbiome: Mechanistic insights into microbial community assembly and resistome dissemination. Although the threat of antibiotic resistance genes (ARGs) in agriculture to human health has raised concerns, there is still a lack of effective and environmentally friendly measures to mitigate antibiotic resistance. Indole-3-acetic acid (IAA) and root exudates are environmentally friendly natural substances. However, the development of technologies harnessing their potential to suppress agricultural ARGs remains unexplored. Here, IAA-mediated key root exudates, N-acetylserotonin and N-methyltryptamine, were found to effectively reduce ARGs in rhizosphere soil. They affected microbial community assembly and further shaped ARGs profiles. Additionally, they inhibited antibiotic-resistant bacteria, potentially suppressing the vertical transfer of ARGs. More importantly, N-acetylserotonin and N-methyltryptamine inhibited ARGs conjugative transfer through suppressing pili assembly and homologous recombination. Overall, IAA-mediated root exudates reduce ARGs in rhizosphere soil by influencing microbial community assembly and inhibiting ARGs transfer. This study provides inspiration for the development of technologies related to plant auxins and root exudates to reduce ARGs in agriculture.202540850579
7456170.9992Anaerobic digestion of nitrogen rich poultry manure: Impact of thermophilic biogas process on metal release and microbial resistances. Poultry manure is a nitrogen rich fertilizer, which is usually recycled and spread on agricultural fields. Due to its high nutrient content, chicken manure is considered to be one of the most valuable animal wastes as organic fertilizer. However, when chicken litter is applied in its native form, concerns are raised as such fertilizers also include high amounts of antibiotic resistant pathogenic Bacteria and heavy metals. We studied the impact of an anaerobic thermophilic digestion process on poultry manure. Particularly, microbial antibiotic resistance profiles, mobile genetic elements promoting the resistance dissemination in the environment as well as the presence of heavy metals were focused in this study. The initiated heat treatment fostered a community shift from pathogenic to less pathogenic bacterial groups. Phenotypic and molecular studies demonstrated a clear reduction of multiple resistant pathogens and self-transmissible plasmids in the heat treated manure. That treatment also induced a higher release of metals and macroelements. Especially, Zn and Cu exceeded toxic thresholds. Although the concentrations of a few metals reached toxic levels after the anaerobic thermophilic treatment, the quality of poultry manure as organic fertilizer may raise significantly due to the elimination of antibiotic resistance genes (ARG) and self-transmissible plasmids.201727932039
8574180.9992Impact of different manure-derived dissolved organic matters on the fate of arsenic-antibiotic in co-contaminated paddy soils. Manure application increases the transfer risk of antibiotic resistance to farmland. Especially, its impact remains unclear when it occurs in arsenic (As)-contaminated paddy soils, which is considered as a global environmental problem. In this work, we investigated the fate of antibiotic resistance genes (ARGs) in As-antibiotic co-contaminated paddy soils under the application of manure from different sources (pig manure, cow dung, and chicken manure). Differences in the aliphatic carbon and electron-donating capacities of these dissolved organic matters (DOM) regulated the transformation of iron and As by both biotic and abiotic processes. The regulation by pig manure was stronger than that by cow dung and chicken manure. DOM regulation increased the abundance of As-related functional genes (arsC, arrA, aioA, and arsM) in the soil and accelerated the transformation of As speciation, the highest proportion of As(III) being 45%-61%. Meanwhile, the continuous selection pressure provided by the highly toxic As(III) increased the risk of ARGs and mobile genetic elements (MGEs) via horizontal gene transfer. As-resistant bacteria, including Bacillus, Geobacter, and Desulfitobacterium, were finally considered as potential host bacteria for ARGs and MGEs. In summary, this study clarified the synergistic mechanism of As-antibiotic on the fate of ARGs in co-contaminated paddy soils, and provided practical guidance for the proper application of organic fertilizers.202235491001
6997190.9992Linkage of antibiotic resistance genes, associated bacteria communities and metabolites in the wheat rhizosphere from chlorpyrifos-contaminated soil. Rhizosphere is a crucial site for the proliferation of antibiotic resistance genes (ARGs) in agricultural soil. Pesticide contamination is ubiquitous in soil, such as chlorpyrifos as one of the most commonly used pesticides. However, limited knowledge is reported about ARGs profiles changes and the driving mechanism of ARGs prevalence in rhizosphere soil after adding pesticide. In this study, irrespective of chlorpyrifos presence, the abundances of ARGs (tetM, tetO, tetQ, tetW, tetX, sul1 and sul2) and intI1 in rhizosphere soil of wheat were obviously higher than those in bulk soil. 20.0 mg·kg(-1) chlorpyrifos significantly increased the abundance of total ARGs and intI1 in bulk soil, respectively, at day 50 and 100, but not in rhizosphere soil. Rhizosphere influence on ARGs was far greater than chlorpyrifos. ARGs and intI1 abundances were higher at day 50 than ones at day 100. C/N ratio and NO(3)(-)-N content, which were affected by rhizosphere and cultivation time, significantly explained the increased ARGs. Compared to bulk soil, rhizosphere shifted host bacteria of tetracycline resistance genes (TRGs), intI1 at genus level, and host bacteria of sul1, sul2 at phylum level. Rhizosphere simplified the linkage of ARGs, host bacteria and metabolites. Bacterial communities played important roles in the variation of ARGs and intI1, and the difference in the distribution of potential hosts between bulk and rhizosphere soil was related to metabolites abundance and composition. These results provide valuable information for understanding the linkage of ARGs, associated bacteria communities and metabolites in the wheat rhizosphere soil.202032615437