Carbohydrate-metabolizing gastrointestinal bacteria mediate resistome divergence in high feed efficiency Holstein dairy calves. - Related Documents




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764401.0000Carbohydrate-metabolizing gastrointestinal bacteria mediate resistome divergence in high feed efficiency Holstein dairy calves. Improvements in feed efficiency often involve alterations in nutrient metabolism mediated by gastrointestinal microorganisms. These microorganisms serve as carriers of antibiotic resistance genes (ARGs); therefore, metabolic changes may influence the dissemination of ARGs. In this study, we investigated the variations in gastrointestinal ARGs between female Holstein calves exhibiting low residual feed intake (LRFI) with high feed efficiencies and those exhibiting high residual feed intake (HRFI) with low feed efficiencies. Metagenomics was conducted to analyze the underlying factors driving these differences. The LRFI calves exhibited 16.6 % higher ruminal ARG abundance but had reduced fecal ARG diversity. The abundance of Erysipelotrichaceae enrichment in LRFI rumen drove resistance functions and elevated carbohydrate-active enzymes (CAZymes) expression. Correlation analysis linked LRFI rumen enriched bacteria Erysipelotrichaceae and Coprobacillaceae to CAZymes, which were positively associated with multidrug, fluoroquinolone, and MLS resistance functions. Weighted Gene Co-Expression Network Analysis confirmed these resistance functions were dominant in LRFI calves. CAZymes improved substrate utilization, enhanced bacterial efflux resistance, promoted bacterial proliferation, and upregulated resistance genes. Rumen microbes and their resistomes systemically alter microbiota and ARG profiles in the feces. The contributions of fecal microbial abundance and diversity, mobile genetic elements (MGEs), and starch to the differences in ARGs were 14.92 %, 11.18 %, 8.90 %, and 10.25 %, respectively. In summary, LRFI calves require more CAZymes to reshape gut microbiota and ARG carrier populations, which lead to shifts in gastrointestinal ARG abundance/diversity shifts.202541172852
802410.9995High Concentrations of Tilmicosin Promote the Spread of Multidrug Resistance Gene tolC in the Pig Gut Microbiome Through Mobile Genetic Elements. The impact of antibiotic therapy on the spread of antibiotic resistance genes (ARGs) and its relationship to gut microbiota remains unclear. This study investigated changes in ARGs, mobile genetic elements (MGEs), and gut microbial composition following tilmicosin administration in pigs. Thirty pigs were randomly divided into control (CK), low-concentration (0.2 g/kg; L), and high-concentration (0.4 g/kg; H) groups. Tilmicosin concentration in manure peaked on day 16 of dosing and dropped below detectable levels by day 13 of the withdrawal period. While tilmicosin did not significantly affect the total abundance of macrolide resistance genes (MRGs) (p > 0.05), it significantly increased the abundance of the multidrug resistance gene tolC in the H group compared with the L and CK groups during the withdrawal period (p < 0.05). This increase was associated with a coincidental rise in the abundance of MGEs (e.g., int1 and int2) and the growth of potential tolC-hosting bacteria such as Paenalcaligenes and Proteiniclasticum. Redundancy analysis showed gut microbial composition as the primary driver of MRG abundance, with MGEs, tilmicosin concentration, and manure physicochemical properties playing secondary roles. These findings suggest that high-dose tilmicosin may alter the gut microbiota and promote ARG spread via MGE-mediated transfer.202439795013
703820.9994Interactions between fungi and bacteria hosts carrying MGEs is dominant for ARGs fate during manure mesophilic composting. The mycelial networks of fungi promote the interaction between the originally isolated bacteria, thereby potentially enhancing the exchange of nutrients and the horizontal transfer of genetic materials. However, the driving effect of fungi on antibiotic resistance genes (ARGs) during mesophilic facultative composting is still unclear. This study aims to elucidate the changes in ARGs and underlying mechanisms during the mesophilic composting of manure. Results indicated that reduction rates of ARGs in sheep and pig manure over a 90-day composting period were 34.68% and 60.10%, respectively. The sul1, sul2 and tetX were identified as recalcitrant ARGs in both composting treatments, with the additional unique recalcitrant gene addA observed in sheep manure. Fungal communities appeared to have a more significant influence on the cooperation between bacteria and fungi. Massive fungi interacted intensively with bacterial hosts carrying both ARGs and mobile genetic elements (MGEs). In sheep and pig manure, there were 53 and 38 potential bacterial hosts (genus level) carrying both ARGs and MGEs, associated close interactions with fungi. Structural equation modeling revealed that compost properties influence ARGs by affecting the abundance of core fungi and the hosts carrying MGEs, and that core fungi could also impact ARGs by influencing the bacterial hosts carrying MGEs. Core fungi have the potential to facilitate the horizontal transfer of ARGs by enhancing bacterial network interactions.202539764902
701030.9994Dynamics of metal(loid) resistance genes driven by succession of bacterial community during manure composting. Metal(loid) resistance genes (MRGs) play important roles in conferring resistance to metal(loid)s in bacterial communities. How MRGs respond to bacterial succession during manure composting remains largely unknown. Metagenomics was used in the present study to investigate the compositional changes of MRGs, their candidate hosts and association with integrons during thermophilic composting of chicken manures. MRGs conferring resistance to 20 metal(loid)s were detected, and their diversity and abundance (normalized to the abundance of 16S rRNA genes) were significantly reduced during composting. MRGs associated with integron were exclusively observed in proteobacterial species. Class 1 integron likely played an important role in maintaining mercury-resistance mer operon genes in composts. Escherichia coli harbored the most abundant MRGs in the original composting material, whereas species of Actinobacteria and Bacilli became more important in carrying MRGs during the late phases. There were significant linear relationships between the relative abundance of some specific bacterial species (E. coli, Actinobacteria species and Enterococcus faecium) and the abundance of MRGs they potentially harbored. The succession of these bacteria contributed to an overall linear regression between the relative abundance of all predicted candidate hosts and the abundance of total MRGs. Our results suggest that the succession of bacterial community was the main driver of MRG dynamics during thermophilic composting.201931563779
696440.9994Metagenomic 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
696650.9994Effects 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
807960.9994Response of antibiotic resistance to the co-exposure of sulfamethoxazole and copper during swine manure composting. Heavy metals driven co-selection of antibiotic resistance in soil and water bodies has been widely concerned, but the response of antibiotic resistance to co-existence of antibiotics and heavy metals in composting system is still unknown. Commonly used sulfamethoxazole and copper were individually and jointly added into four reactors to explore their effects on antibiotic resistance genes (ARGs), mobile genetic elements (MGEs), heavy metal resistance genes (MRGs) and bacterial community structure. The abundance of total ARGs and MGEs were notably decreased by 68.64%-84.95% and 91.27-97.38%, respectively, after the composting. Individual addition of sulfamethoxazole, individual addition of copper, simultaneously addition of sulfamethoxazole and copper increased the abundance of ARGs and MGEs throughout the composting period. Co-exposure of sulfamethoxazole and copper elevated the total abundance of ARGs by 1.17-1.51 times by the end of the composting compared to individual addition of sulfamethoxazole or copper. Network analysis indicated that the shifts in potential host bacteria determined the ARGs variation. Additionally, MGEs and MRGs had significant effects on ARGs, revealing that horizontal gene transfer and heavy metals induced co-resistance could promote ARGs dissemination.202234537705
694670.9994Persistence of Salmonella Typhimurium and antibiotic resistance genes in different types of soil influenced by flooding and soil properties. Salmonella is a zoonotic foodborne bacterial pathogen that can seriously harm health. Persistence of Salmonella and antibiotic resistance genes (ARGs) in different types of soil under flooding and natural conditions are rare explored. This study investigated the dynamic changes of the Salmonella, ARGs and bacterial communities in three types of soils applied with pig manure in lab scale. Abundance of the Salmonella Typhimurium in soils reduced to the detection limit varied from 40 to 180 days, most of the Salmonella did not survive in soil for more than 90 days. Flooding and soil texture (content of sand) promote the decline rate of Salmonella. No Salmonella was found have acquired resistance gene from the soil or manure after 90 days. 64 ARGs and 11 MGEs were quantified, abundance of these genes and risky ARGs both gradually decline along with the extension of time. Most of the extrinsic ARGs cannot colonize in soil, cellular protection and antibiotic deactivation were their main resistance mechanism. Multidrug resistance and efflux pump were the dominant class and mechanism of soil intrinsic ARGs. Flooding can affect the ARGs profiles by reducing the types of extrinsic ARGs invaded into soil and inhibit the proliferation of intrinsic genes. Soil sand content, soil moisture and nutrition concentrations had significant direct effect on the abundance or profile of ARGs. Soil bacterial community structures also changed along with the extension of time and affected by flooding. Network analyses between ARGs and bacteria taxa revealed that Actinobacteria and Myxococcia were the main hosts of intrinsic ARGs, some taxa may play a role in inhibiting extrinsic ARGs colonization in the soils. These findings unveil that saturate soil with water may play a positive role in reducing potential risk of Salmonella and ARGs in the farmland environment.202236436254
703380.9994Environmental drivers and interaction mechanisms of heavy metal and antibiotic resistome exposed to amoxicillin during aerobic composting. The environmental accumulation and spread of antibiotic resistance pose a major threat to global health. Aerobic composting has become an important hotspot of combined pollution [e.g., antibiotic resistance genes (ARGs) and heavy metals (HMs)] in the process of centralized treatment and resource utilization of manure. However, the interaction mechanisms and environmental drivers of HMs resistome (MRGs), antibiotic resistance (genotype and phenotype), and microbiome during aerobic composting under the widely used amoxicillin (AMX) selection pressure are still poorly understood. Here, we investigated the dynamics of HMs bioavailability and their MRGs, AMX-resistant bacteria (ARB) and antibiotic resistome (ARGs and intI1), and bacterial community to decipher the impact mechanism of AMX by conducting aerobic composting experiments. We detected higher exchangeable HMs and MRGs in the AMX group than the control group, especially for the czrC gene, indicating that AMX exposure may inhibit HMs passivation and promote some MRGs. The presence of AMX significantly altered bacterial community composition and AMX-resistant and -sensitive bacterial structures, elevating antibiotic resistome and its potential transmission risks, in which the proportions of ARB and intI1 were greatly increased to 148- and 11.6-fold compared to the control group. Proteobacteria and Actinobacteria were significant biomarkers of AMX exposure and may be critical in promoting bacterial resistance development. S0134_terrestrial_group was significantly negatively correlated with bla(TEM) and czrC genes, which might play a role in the elimination of some ARGs and MRGs. Except for the basic physicochemical (MC, C/N, and pH) and nutritional indicators (NO(3) (-)-N, NH(4) (+)-N), Bio-Cu may be an important environmental driver regulating bacterial resistance during composting. These findings suggested the importance of the interaction mechanism of combined pollution and its synergistic treatment during aerobic composting need to be emphasized.202236687604
808090.9994Fates of antibiotic resistance genes and bacterial/archaeal communities of activated sludge under stress of copper: Gradient increasing/decreasing exposure modes. Effect of copper (Cu) on antibiotic resistance genes (ARGs) and bacterial/archaeal community of activated sludge under gradient increasing (0.5-10 mg/L) or decreasing exposure (10-0.5 mg/L) modes was explored. Here, 29 genes were detected among 48 selected ARGs and mobile gene elements (MGEs). Two exposure modes showed dissimilar effects on ARGs and distribution was more affected by environmental concentrations of Cu, which promoted transmission of ARGs (multiple drug resistance and sulfonamide). Cellular protection was main resistance mechanism, which was less inhibited than efflux pumps. The tnpA-02, as main MGE, interacted closely with ARGs (sul2, floR, etc.). Gradient increasing exposure mode had more effects on bacterial/archaeal structure and composition. Bacteria were main hosts for specific ARGs and tnpA-02, while archaea carried multiple ARGs (cmx(A), adeA, etc.), and bacteria (24.24 %) contributed more to changes of ARGs than archaea (19.29 %). This study clarified the impacts of Cu on the proliferation and transmission of ARGs.202236096328
6971100.9994Spontaneous fermentation mitigates the frequency of genes encoding antimicrobial resistance spreading from the phyllosphere reservoir to the diet. The phyllosphere microbiome of vegetable products constitutes an important reservoir for multidrug resistant bacteria and Antibiotic Resistance Genes (ARG). Vegetable products including fermented products such as Paocai therefore may serve as a shuttle for extrinsic microorganisms with ARGs into the gut of consumers. Here we study the effect of fermentation on Paocai ARG dissemination by metagenomic analysis. Microbial abundance and diversity of the Paocai microbiome were diminished during fermentation, which correlated with the reduction of abundance in ARGs. Specifically, as fermentation progressed, Enterobacterales overtook Pseudomonadales as the predominant ARG carriers, and Lactobacillales and Enterobacteriales became the determinants of Paocai resistome variation. Moreover, the dual effect of microbes and metal resistance genes (MRGs) was the major contributor driving Paocai resistome dynamics. We recovered several metagenome-assembled genomes (MAGs) carrying acquired ARGs in the phyllosphere microbiome. ARGs of potential clinical and epidemiological relevance such as tet M and emrB-qacA, were mainly hosted by non-dominant bacterial genera. Overall, our study provides evidence that changes in microbial community composition by fermentation aid in constraining ARG dispersal from raw ingredients to the human microbiome but does not eliminate them.202438677439
7034110.9994Meta-analysis reveals the processes and conditions of using biochar to control antibiotic resistance genes in soil. Soil is a significant reservoir of antibiotic resistance genes (ARGs) and an important habitat for pathogens associated with many clinical infections and plant disease outbreaks. Although scientists have found that biochar can reduce ARGs in soil, the understanding of how biochar removes soil ARGs and the influencing factors remains limited. Here, a meta-analysis of 65 published studies was conducted to illuminate the mechanisms through which biochar remediates ARG-contaminated soils. In biochar-amended soil, the antibiotic content significantly decreased by 24.1 %, while the abundances of mobile genetic elements and ARG host bacteria declined by 23.5 % and 12.1 %, respectively. The reduced antibiotic content, suppressed mobile genetic elements, and altered bacterial community structure collectively led to a 41.8 % reduction in soil ARG abundance. In addition, wood-derived biochar pyrolyzed at 300-500 °C exhibited a substantial advantage in the remediation of ARGs. Furthermore, biochar application decreased the abundance of ARGs in alkaline and neutral soil more markedly than that in acidic soil. The results of this research confirmed the positive mitigating effect of biochar on ARGs in soil, providing valuable insights for the prevention and control of ARG pollution.202540359860
7516120.9994Functional gene array-based analysis of microbial communities in heavy metals-contaminated lake sediments. Lake DePue (IL, USA) has been contaminated for > 80 years by an adjacent Zn-smelting facility. Previous work indicated that sulfate reduction increased and biomass declined as pore-water metal concentrations increased, while 16S rRNA gene profiles remained relatively stable. To better understand this phenomenon, the sediment microbial community structure and functional potential were investigated using a functional gene microarray (GeoChip) targeting > 10,000 functional genes. Nonmetric multidimensional scaling and clustering analyses showed that the overall community structure was similar across all sites based on the relative abundance of all detected genes, but some individual gene categories did show differences. A subset of sulfate reduction genes (dsr) and the most relevant metal resistance genes were more abundant than other categories and were highly correlated with metal contamination. The most significant correlations were between pore-water metal concentrations and dsr, with Zn, Cd, and Mn as the most predictive for the presence of dsr. These results suggest that metal contamination influences sediment microbial community structure and function by increasing the abundance of relevant metal-resistant and sulfate-reducing populations. These populations therefore appear to contribute significantly to the resistance and stability of the microbial communities throughout the gradient of metal contamination in Lake DePue.201323710534
6912130.9994Regulation 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
6894140.9994Profiles of antibiotic- and heavy metal-related resistance genes in animal manure revealed using a metagenomic analysis. Farmed animals produce excrement containing excessive amounts of toxic heavy metals as a result of consuming compound feed as well as receiving medical treatments, and the presence of these heavy metals may aggravate the risk of spreading drug-resistance genes through co-selection during manure treatment and application processes. However, research on the association between heavy metals and antimicrobial resistance is still lacking. In this study, metagenomic sequencing was used to explore the effects of the co-selection of environmentally toxic heavy metals on the resistome in manure. A relevance network analysis showed that metal-resistance genes (MRGs), especially for copper (Cu) and zinc (Zn), were positively correlated with multiple types of antibiotic-resistance genes (ARGs) and formed a complex network. Most bacteria that co-occurred with both MRGs and ARGs simultaneously are members of Proteobacteria and accounted for 54.7% of the total microbial species in the relevance network. The remaining bacteria belonged to Firmicutes, Bacteroidetes and Actinobacteria. Among the four phyla, Cu- and Zn-resistance genes had more complex correlations with ARGs than other MRG types, reflecting the occurrence of ARG co-selection under the selective pressure of high Cu and Zn levels. In addition, approximately 64.8%, 59.1% and 68.4% of MRGs that correlated with the presence of plasmids, viruses and prophages, respectively, are Cu- or Zn-resistant, and they co-occurred with various ARGs, indicating that mobile genetic elements participate in mediating ARG co-selection in response to Cu and Zn pressure. The results indicated that the use of heavy-metal additives in feed induces the increases of drug resistance genes in manure through co-selection, aggravating the risk of antimicrobial resistance diffusion from animal farm to manure land applications.202235617901
6880150.9994Co-occurrence and co-expression of antibiotic, biocide, and metal resistance genes with mobile genetic elements in microbial communities subjected to long-term antibiotic pressure: Novel insights from metagenomics and metatranscriptomics. The burgeoning of antibiotic resistance has emerged as a pressing global challenge. To gain a deeper understanding of the interactions between antibiotic resistance genes (ARGs), biocide and metal resistance genes (BRGs&MRGs), and mobile genetic elements (MGEs), this study utilized metagenomics and metatranscriptomics to investigate their co-occurrence and co-expression in two consortia subjected to long-term exposure to chloramphenicol and lincomycin. Long-term exposure to these antibiotics resulted in significant disparities in resistance profiles: Consortium(CAP) harbored 130 ARGs and 150 BRGs&MRGs, while Consortium(LIN) contained 57 ARGs and 32 BRGs&MRGs. Horizontal gene transfer (HGT) events were predicted at 125 and 300 instances in Consortium(CAP) and Consortium(LIN), respectively, facilitating the emergence of multidrug-resistant bacteria, such as Caballeronia (10 ARGs, 2 BRGs&MRGs), Cupriavidus (2 ARGs, 10 BRGs&MRGs), and Bacillus (14 ARGs, 21 BRGs&MRGs). Chloramphenicol exposure significantly enriched genes linked to phenicol resistance (floR, capO) and co-expressed ARGs and BRGs&MRGs, while lincomycin exerted narrower effects on resistance genes. Additionally, both antibiotics modulated the expression of degradation genes and virulence factors, highlighting their role in altering bacterial substrate utilization and pathogenic traits. This study provides quantitative insights into the impact of antibiotics on microbial resistance profiles and functions at both DNA and RNA levels, highlighting the importance of reducing antibiotic pollution and limiting the spread of resistance genes in the environment.202539965334
7561160.9994Deciphering antibiotic resistome variations during nitrogen removal process transition under mixed antibiotics stress: Assembly process and driving factors. Antibiotic resistome, which encompasses all types of antibiotic resistance genes (ARGs) in a given environment, has received increasing attention in research on different wastewater treatment processes. However, the variation in antibiotic resistome during the transition from the full nitrification-denitrification to the shortcut nitrification-denitrification process remains unclear. In this study, a total of 269 targeted gene subtypes were identified, along with 108 genes were consistently present in all samples. The introduction of mixed antibioticsrapidly increased the abundance of corresponding and non-corresponding ARGs, as well as that of mobile genetic elements.The variations in of the antibiotic resistome were primarily driven by dissolved oxygen and nitrite accumulation rate. Moreover, 34 bacterial genera were identified as potential ARG hosts, with most denitrifiers considered as potential antibiotic-resistant bacteria, including Branchymonas, Rhodobacter, and Thauera. This study provides a method for controlling antibiotic resistance by regulating the changes in environmental variables and bacterial communities.202339492537
7012170.9994Bacterial communities, metabolic functions and resistance genes to antibiotics and metals in two saline seafood wastewater treatment systems. This study investigated the bacterial communities, metabolic functions, antibiotic resistance genes (ARGs) and metal resistance genes (MRGs) in two alternating anaerobic/aerobic biological filters (A/O-BFs) treating saline seafood wastewater (SSW). Firmicutes was the most abundant phylum in both systems, and halophilic and alkaliphilic bacteria were largely enriched. 15 potential pathogens were obtained. Metabolism was the predominant bacterial function. 49 ARGs and 7 MRGs were detected, and the total abundance of ARGs increased while that of MRGs decreased. Clear shifts in bacterial structure and function, ARGs and MRGs were observed in both systems and at different heights. Co-occurrence of ARGs and MRGs and their hosts were identified. ARGs and MRGs mainly negatively correlated with bacterial functions, which were also the important contributors to shifts in bacterial communities and functions. This study highlights the importance of investigating ARGs and MRGs in SSW treatment systems and their complex interactions with bacterial communities and functions.201931121446
6967180.9994Effects 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
7419190.9994The bacterial microbiota in florfenicol contaminated soils: The antibiotic resistome and the nitrogen cycle. Soil antibiotic resistome and the nitrogen cycle are affected by florfenicol addition to manured soils but their interactions have not been fully described. In the present study, antibiotic resistance genes (ARGs) and nitrogen cycle genes possessed by soil bacteria were characterized using real-time fluorescence quantification PCR (qPCR) and metagenomic sequencing in a short-term (30 d) soil model experiment. Florfenicol significantly changed in the abundance of genes conferring resistance to aminoglycosides, β-lactams, tetracyclines and macrolides. And the abundance of Sphingomonadaceae, the protein metabolic and nitrogen metabolic functions, as well as NO reductase, nitrate reductase, nitrite reductase and N(2)O reductase can also be affected by florfenicol. In this way, ARG types of genes conferring resistance to aminoglycosides, β-lactamases, tetracyclines, colistin, fosfomycin, phenicols and trimethoprim were closely associated with multiple nitrogen cycle genes. Actinobacteria, Chlorobi, Firmicutes, Gemmatimonadetes, Nitrospirae, Proteobacteria and Verrucomicrobia played an important role in spreading of ARGs. Moreover, soil physicochemical properties were important factors affecting the distribution of soil flora. This study provides a theoretical basis for further exploration of the transmission regularity and interference mechanism of ARGs in soil bacteria responsible for nitrogen cycle.202032023788