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Optimizing a culture-enriched hybrid metagenomics pipeline to assess the AMR footprint of livestock manure in anaerobic digestate.

The role of environmental samples from livestock production systems, including manure and anaerobic digestate, as reservoirs of antimicrobial resistance genes (ARGs) is likely underestimated because conventional metagenomic approaches can overlook low-abundance ARGs and often lack the resolution to associate these genes with their microbial hosts and co-localized mobile genetic elements (MGEs). We evaluated whether culture-enriched metagenomics (CEMG), with and without antibiotic selection, enhances ARG detection in anaerobic digestate and improves the resolution of ARG-MGE-host associations using hybrid short- and long-read metagenomic assembly. CEMG increased ARG recovery; mean ARG abundance rose from 15.4 counts per million (CPM) in metagenomic fresh digestate (FD) to 124 CPM in CEMG without antibiotics and 160 CPM in antibiotic-selective CEMG. In FD, only 9 unique ARGs were detected, whereas CEMG recovered 112, including ARGs of clinical importance, such as glycopeptide resistance, beta-lactamase genes, and the cfr 23S rRNA methyltransferase conferring cross-resistance to multiple antibiotic classes. Antibiotic selection induced targeted, class-specific shifts in ARG profiles, with ARGs associated with tetracycline resistance consistently enriched across treatments. Hybrid metagenomic assembly resolved the genomic context of 784 ARGs, of which 59.3% were co-localized with at least one class of MGEs, predominantly plasmids and integrative conjugative elements/integrative mobilizable elements. Biocide and metal resistance genes frequently co-occurred with ARGs on the same contigs. Together, these findings demonstrate that antibiotic-selective culture enrichment enhances resistome surveillance by improving detection of low-abundance ARGs, while hybrid assembly provides critical genomic context for assessing their mobility and host associations.IMPORTANCELivestock manure and its byproducts, such as anaerobic digestate, are recognized as important environmental reservoirs of antimicrobial resistance genes (ARGs) and resistant bacteria, yet current metagenomic approaches may underestimate this risk by failing to detect low-abundance but clinically relevant ARGs. Here, we show that integrating culture enrichment with hybrid metagenomics improves ARG recovery and reveals ARG co-localization with mobile genetic elements and putative bacterial hosts. This approach captures a cultivable and condition-responsive fraction of the resistome that is not readily accessible through direct metagenomic sequencing alone, providing a more informative framework for environmental AMR surveillance.

anaerobic digestion

Repurposing anti-phage defenses to differentially arrest the viral lifecycle reveals the regulatory logic of a parasitic satellite.

Mobile genetic elements frequently encode defense mechanisms to protect their bacterial hosts from viral attack. In Vibrio cholerae, these defensive elements include phage-inducible chromosomal island-like elements (PLEs), which are phage satellites that act as highly specialized parasites of the lytic phage ICP1. While PLE transcriptional activation upon ICP1 infection is known to be temporally regulated, the underlying regulatory logic and dependencies on the progression of the phage's developmental program required for activation remain unclear. In this study, we took a novel approach to define these dependencies by introducing independent anti-phage defense systems, BREX and DarTG, as molecular roadblocks to impede the ICP1 lifecycle. We discovered that, for both ICP1 and PLE, late-stage gene expression is fundamentally uncoupled from genome replication, representing a striking departure from the standard paradigm for double-stranded DNA phages. While BREX restricts ICP1 to an immediate-early transcriptional state that stalls PLE activation, DarTG allows the phage to execute its full transcriptional cascade despite the total block in DNA replication. This permissive environment provides the necessary cue(s) for complete PLE induction, revealing that robust PLE activation is profoundly dependent on the transcriptional progression of its helper phage.IMPORTANCEBacteria and their viruses (phages) are locked in perpetual evolutionary conflict. Some bacteria harbor phage satellites, specialized parasites that are activated to hijack the phage's components to spread all the while inhibiting viral production. While some satellites respond to a single viral trigger, the regulation of many satellites, including clinically relevant phage-inducible chromosomal island-like elements (PLEs) in Vibrio cholerae, remains poorly understood. Here, we used bacterial defense systems as molecular roadblocks to probe how PLE activation depends on its helper phage. We found that severe disruptions to viral transcription stall PLE activation. Unexpectedly, both the virus and the satellite can execute their full transcriptional programs even when DNA replication is completely blocked, challenging a fundamental paradigm in virology. These insights reveal a sophisticated level of phage-satellite coordination, illustrating how satellite activation is tightly linked to the transcriptional state of its helper phage, a dependency that ultimately drives the dissemination of mobile genetic elements.

Vibrio cholerae

Spatiotemporal genomic analysis and risk assessment of the plasmids carrying blaOXA-48-like genes based on a large-scale international dataset.

BACKGROUND: The spread of OXA-48-like carbapenemases represents a major public health challenge. Although previous studies have investigated OXA-48-like carbapenemases risk factors, nosocomial dissemination, and plasmid dynamics, an integrated plasmid-centered framework combining complete plasmid mining, transmission-unit analysis, phylogenetic reconstruction, and machine learning-based risk assessment remains limited. METHODS: We systematically collected 747 complete plasmid sequences carrying blaOXA-48-like genes from the NCBI database, establishing the largest collections of complete plasmid sequences to date. Using an integrative framework of population genomics, phylogenetic dating, and machine learning, this study aimed to characterize the dissemination patterns, plasmid replicon diversity, transmission units, mobile genetic elements, co-resistance profiles, and risk classification of these plasmid. RESULTS: Plasmids carrying blaOXA-48-like genes were detected across 50 countries on six continents, with blaOXA-48 predominating in Europe, blaOXA-181 in South Asia, and blaOXA-232 largely in Asia. IncL and ColKP3/IncX3 replicons, together with Tn1999.2 and other MGEs, were central drivers of plasmid maintenance and spread. Sixteen transmission units were defined, with AA068_Cluster3 estimated to have originated in the Netherlands around 2005 before expanding to Europe, the Middle East, Asia, and North America. Co-resistance analyses revealed frequent modules involving aminoglycoside and quinolone resistance, with qnrS1 and aph(3'')-Ib most prevalent. Notably, high-risk transposon structures were often identified in non-clinical environments, underscoring their cross-ecological transmission potential. Machine learning-based classification models showed good internal performance for predefined composite-risk categories, with plasmid mobility, clinical/non-clinical source composition, and host background contributing to the classification results. CONCLUSIONS: This study provides a large-scale plasmid-centered genomic analysis of publicly available complete plasmid sequences carrying blaOXA-48-like genes, integrating transmission-unit inference, phylogeographic reconstruction, mobile genetic element and co-resistance profiling, and composite genomic risk stratification. This gene-centered framework may support future One Health-oriented antimicrobial resistance surveillance and prioritization of plasmids with higher dissemination and resistance potential.

Plasmids

Universal versus targeted chlorhexidine and mupirocin decolonisation and clinical and molecular epidemiology of Staphylococcus epidermidis bloodstream infections in patients in intensive care in Scotland, UK: a controlled time-series and longitudinal genotypic study.

BACKGROUND: There are concerns that biocide skin and mucous membrane decolonisation, which is widely used to prevent health-care-associated infections in intensive care units (ICUs), might select for multidrug-resistant pathogens. We aimed to evaluate the effects of de-escalating from universal to targeted skin and nasal decolonisation on Staphylococcus epidermidis bloodstream infections (SE-BSI). METHODS: We did a retrospective, before-after-control-impact time-series analysis and longitudinal genotypic study in two ICUs with divergent decolonisation practice in tertiary care hospitals of adjacent health boards in Scotland, UK. Participants were aged at least 16 years and admitted between July 1, 2009, and Feb 28, 2022. There were no exclusion criteria for the study. In ICU one (intervention site) universal decolonisation in all admissions was de-escalated to targeted decolonisation of meticillin-resistant Staphylococcus aureus (MRSA) carriers on Feb 1, 2019, while in ICU two (control site) targeted decolonisation was applied throughout. We collected bloodstream infection data from all causes, including clinically significant SE-BSI. Antimicrobial susceptibility testing was used to define meticillin-resistant S epidermidis (MRSE) and chlorhexidine susceptibility. We used multilocus sequence typing to identify sequence types from archived SE-BSI isolates. Whole-genome sequencing was applied to a sample from ICU one. The primary outcomes were incidence densities of all bloodstream infections, SE-BSI, and meticillin-resistant S epidermidis bloodstream infections (MRSE-BSI), and the percentage probability that SE-BSI were MRSE-BSI. The effects of de-escalation on primary outcomes were estimated by differences between the intervention and control sites, before and after de-escalation, using a before-after-control-impact time-series design. Secondary outcomes included the proportion of multidrug resistant sequence types, carriage of mobile genetic elements and genes for multidrug resistance and biofilm production. FINDINGS: Between July 1, 2009, and Feb 28, 2022, S epidermidis was identified in 334 (45%) of 735 bloodstream infections in ICU one, of which 197 occurred before the de-escalation intervention in Feb 1, 2019, and S epidermidis was identified in 167 (60%) of 278 bloodstream infections in ICU two. There was no increase in all bloodstream infection incidence coinciding with de-escalation in ICU one, whereas MRSE-BSI incidence declined significantly from 10·4 cases per 1000 occupied bed days (OBDs; 95% credible interval [CrI] 7·2-15·4) to 4·3 cases per 1000 OBDs (2·5-6·7), as did the percentage probability of MRSE (from 89·2%, 95% CrI 77·8-96·5 to 56·7%, 34·3-77·5%). No significant changes in the primary outcomes were seen in ICU two. MRSE-BSI incidence density was positively associated with chlorhexidine use, but not mupirocin use. De-escalation was associated with a reduced proportion of SE-BSI due to multidrug-resistant sequence types and reduced carriage of mobile genetic elements and genes for multidrug resistance and biofilm production, as observed by multi-locus sequence typing and whole genome sequencing. INTERPRETATION: In ICU settings with low MRSA incidence, the benefits of universal decolonisation should be balanced against the risks of selecting MRSE sequence types adapted for invasive and device-associated infection. FUNDING: National Health Service Grampian Charity.

Humans

Identification of essential genes for conjugative transfer in antimicrobial resistance-associated pELF-type linear plasmids of opportunistic pathogen Enterococcus faecium.

The pELF-type linear plasmid is a critical mobile genetic element responsible for the dissemination of various antimicrobial resistance (AMR) genes, most notably vancomycin resistance in Enterococcus faecium, which is a leading cause of hospital outbreaks worldwide. Despite their crucial role in the expansion of AMR, the molecular mechanisms underlying the conjugative transfer of these linear plasmids remain poorly understood. In this study, the transfer (tra) region of pELF2, a representative vanA-harboring linear plasmid was characterized. Transcriptomic data suggested that the FtsK/VirD4-type adenosine triphosphatase is encoded within a multi-gene operon. By developing a genetic manipulation framework for E. faecium, an extensive mutational analysis of the tra region was performed and the following three essential genes were identified: traCB4 (a putative VirB4 analog), traDD4 (a VirD4-like coupling protein), and traGB6 (a putative VirB6 analog). These genes are indispensable for conjugative transfer. Reporter assays experimentally confirmed the presence of a functional promoter upstream of the identified tra genes. We confirmed that these genes are highly conserved among pELF-type plasmid sequences deposited in public database. The study findings revealed that pELF-type plasmids utilize highly minimized conjugation machinery, which is similar to unusual systems previously identified in other gram-positive bacteria, such as Streptomyces. This study provides the first molecular insights into the transmission of these clinically important linear plasmids in enterococci and lays a foundation for understanding the dissemination of resistance determinants mediated by atypical mobile genetic elements.

Enterococcus faecium

Fate of antibiotic resistance genes during rural domestic wastewater treatment: Anaerobic unit as enrichment hotspot versus aerobic unit as attenuation zone.

Rural domestic wastewater treatment systems are important but understudied reservoirs for antibiotic resistance genes (ARGs), whose full-process migration mechanisms remain unclear. Herein, the contribution of each treatment unit of ARGs was investigated using metagenomic methods across two seasons in typical rural domestic wastewater treatment systems. Although a removal efficiency (69 % in winter and 22 % in summer) was observed for ARGs, higher antibiotic residues and temperature dramatically induced ARG occurrence in wastewater and horizontal gene transfer (HGT) risk during wastewater treatment. The ARG abundances in the anaerobic unit increased by 1.6-2.1 fold compared to the regulating pool, primarily driven by elevated mobile genetic element (MGE) activity. In sharp contrast, ARG reduction was achieved through ARG host removal and suppressed HGT potential in the aerobic unit. Notably, mobile ARGs were dominated by tetracycline resistance genes in winter and co-dominated by tetracycline and sulfonamide genes in summer, with most flanked by transposases. Key pathogenic hosts, including Klebsiella pneumoniae, Escherichia coli, and Pseudomonas aeruginosa carrying ARG-MGE complexes, were primarily concentrated in the regulating pool and the influent, forming high-risk upstream sources of dissemination. Partial least-squares path model highlighted MGEs as the primary drivers, and variance partitioning analysis indicated that MGEs account for 31 % of the explained variation in ARGs during wastewater treatment. In summary, the anaerobic unit was an ARG enrichment hotspot, while the aerobic unit as ARG attenuation zone during wastewater treatment. These findings provide crucial evidence to optimize rural wastewater treatment processes and to target the control of antibiotic resistance.

Wastewater

Cerium dioxide nanoparticle exposure attenuates mobility-linked antibiotic resistome signatures across the soil-lettuce continuum.

Antibiotic resistance genes (ARGs) are contaminants of emerging concern in agricultural microbiomes. Their association with mobile genetic elements (MGEs) can enhance dissemination across soil-plant interfaces, creating potential environmental and food-chain exposure risks. However, how engineered nanoparticles modulate relative ARG abundance and mobility-linked resistome features in plant-associated microbiomes remains poorly understood. Here, we examined the effects of graded, experimentally elevated cerium dioxide nanoparticle (CeO2 NP) loadings in a soil-lettuce system by integrating compartment-resolved metagenomics, ARG-MGE co-occurrence analysis, putative host-reservoir profiling, transcriptomics, and functional assays. Metagenomic profiling identified 16 ARG types and 125 subtypes and revealed niche-dependent microbiome restructuring under CeO2 NP exposure. Rhizosphere relative ARG abundance showed a negative dose-associated trend, although overall inter-group differences were not significant, whereas leaf endophytes showed a weaker response. Relative MGE abundance decreased significantly in both compartments, and lower assembly-level ARG-MGE co-occurrence reflected fewer ARGs detected in MGE-associated genomic contexts, whereas fewer multi-ARG contigs suggested reduced ARG clustering and potential co-selection. Putative host-reservoir analysis associated key efflux determinants with bacterial families whose relative representation declined following CeO2 NP exposure. Transcriptomic profiling of representative putative ARG hosts revealed host-specific responses, including downregulation of genes involved in central metabolism and Sec-dependent trafficking. Complementary host assays showed reduced apparent envelope permeability and lower recovery of tetracycline-resistant recipient-identity colonies in the plasmid-associated host system. Together, under the tested elevated-loading conditions, CeO2 NP exposure was associated with lower relative ARG signals and weaker mobility-linked resistome features across the soil-lettuce continuum, providing mechanistic insight into nanoparticle-resistome interactions in soil-plant systems.

ARG dissemination

Faecalibacterium harmsenii sp. nov., an abundant but previously overlooked Faecalibacterium in the human gut.

Faecalibacterium is one of the most abundant anaerobes in the human colon. At the genus level, this bacterium shows a strong positive association with human health. Expanding collections of isolates and metagenome-assembled genomes have revealed its species diversity, yet species-level functions remain so far underexplored. Here, we describe a novel species, Faecalibacterium harmsenii. In addition, we reclassify another isolate as a member of the recently reported Faecalibacterium langellae species. Despite close genomic relatedness, these isolates exhibit distinct physiological and biochemical traits, including differences in carbohydrate utilization, stress tolerance, enzymatic activity, Gram-staining and fatty acid composition. Our present comparative genomics analyses further uncover extensive functional diversity and plasticity across type strains, with F. harmsenii being distinguished by an expanded carbohydrate gene repertoire and reduced defense systems, mobile genetic elements and antibiotic resistance genes. Extending to the species, we identify species-specific ecological niches across hosts and differential sensitivities to human diseases, highlighting certain species as reliable biomarkers of gut health. Together, these findings refine our understanding of Faecalibacterium diversity and provide a framework for its use in microbiome-based diagnostics and therapeutic development.

Faecalibacterium harmsenii

SegMantX: A Novel Tool for Detecting DNA Duplications Uncovers Prevalent Duplications in Plasmids.

Segmental duplications play an important role in genome evolution via their contribution to copy-number variation, gene-family diversification, and the emergence of novel functions. The detection of segmental duplications is challenging due to heterogeneous amelioration of sequence similarity among duplicates, which hinders the reconstruction of continuous sequence alignment. Here we introduce SegMantX, a novel approach for the identification of diverged segmental duplications in prokaryote genomes using local alignment chaining. In this approach, local alignments resulting from a preliminary sequence similarity search (e.g. BLASTn) are chained into continuous segments. Evaluating the performance of SegMantX using simulated sequences shows that the tool can detect diverged duplications beyond the sensitivity limits of standard alignment-based methods. Applying SegMantX to 6,784 enterobacterial plasmids, we find that 65% plasmids contain duplicated regions and gene duplications, most of which correspond either to dispersed, noncoding regions or duplicated mobile genetic elements (MGEs; e.g. transposons and insertion sequences). Furthermore, we demonstrate the applicability of SegMantX for the identification of diverged gene transfers between replicons and plasmid hybridization events. Our findings highlight MGEs as drivers of segmental duplications in plasmid evolution, leading to the amplification of their cargo genes, including antibiotic resistance genes. SegMantX provides a powerful framework for reconstructing diverged segmental duplications and other alignment problems.

Plasmids

Microplastics as vectors for microbial pollutants: Biofilm-associated transfer of pathogens and antibiotic resistance genes in zebrafish intestine.

As composite carriers of microorganisms and pollutants, biofilm-attached microplastics (MPs) serve as potential vectors for the environmental migration and biotransmission of antibiotic resistance genes (ARGs) and pathogens. In this study, traditional polypropylene (PP) and biodegradable polylactic acid (PLA) MPs were used to investigate the interference effects of biofilms-attached MPs on gut microbiota and ARGs transmission, through a combination of laboratory biofilm cultivation, zebrafish (Danio rerio) exposure simulations, metagenomic sequencing, and metabolomic profiling. Results showed that MP biofilms likely induced gut dysbiosis and were associated with altered diversity and abundance of pathogens and ARGs. At the phylum level, Nitrospira was transferred from PP biofilms to the gut. At the genus level, 23 genera were transferred from MP biofilms, with PLA (23 genera) showing higher transfer capacity than PP (4 genera). Notably, two human pathogens, one opportunistic pathogen, and two ARGs (adeF and oqxB) were specifically transferred from PLA biofilms, highlighting the unique dissemination risk of biodegradable MPs. Mechanistically, MPs may activate mobile genetic elements (e.g., Tn916 transposon) through metabolic remodeling and quorum sensing, thereby promoting horizontal gene transfer and ARGs dissemination within the gut. Our findings highlight the potential role of MPs as carriers of microorganisms and ARGs, underscoring the biotransmission risks of antibiotic resistance caused by composite pollution.

Animals

Spiramycin fermentation residue-derived biochar regulates soil nutrient cycling, microbial communities, and antibiotic resistance gene dynamics.

Spiramycin fermentation residues (SFR) are hazardous wastes enriched with residual antibiotics, yet they can serve as potential feedstocks for resource recovery after appropriate treatment. In this study, SFR-derived biochar (SFR-BC) was produced by pyrolysis and applied to agricultural soil to evaluate its effects on soil properties, microbial communities, potential pathogenic bacteria, antibiotic resistance genes (ARGs), and mobile genetic elements (MGEs). A 60-day soil incubation experiment was conducted with one control and three SFR-BC application rates of 0.5%, 1.0%, and 2.0%. SFR-BC improved soil physicochemical properties, nutrient status, enzyme activities, and microbial alpha diversity. Metagenomic analysis showed that SFR-BC altered the abundance of functional genes associated with carbon and nitrogen cycling, indicating shifts in microbial functional potential. SFR-BC also changed bacterial co-occurrence patterns, with the high-dose treatment showing a more complex and highly connected network structure during incubation. In addition, high-dose SFR-BC reduced several potential pathogenic bacteria, including major plant pathogenic taxa. SFR-BC decreased soil ARG abundance by 9.38%-33.67% and MGE abundance by 6.49%-27.89% relative to the control, showing a dose-dependent reduction in antibiotic resistance-related genetic elements. Network and PLS-PM analyses further indicated that ARG variation was statistically associated with soil physicochemical properties, microbial diversity, potential bacterial hosts, and MGEs. Overall, these results suggest that SFR-BC can improve short-term soil nutrient status and reduce ARGs, MGEs, and several potential pathogenic taxa under controlled incubation conditions, providing useful evidence for the potential valorization of antibiotic fermentation residues through pyrolysis.

Charcoal

Dynamics of Antibiotic Resistance Gene Profiles in Captive Forest Musk Deer (Moschus berezovskii) Along a Breeding Duration Gradient.

BACKGROUND: To conserve wild populations and ensure a sustainable supply of musk, China initiated the captive breeding of forest musk deer. The temporal dynamics of gut antibiotic resistance gene (ARG) profiles in captive forest musk deer along a breeding duration gradient remain poorly characterized. METHODS: In this study, we employed metagenomic sequencing to systematically characterize the profiles and potential mobility of ARGs. Samples were divided into short-term, medium-term and long-term groups according to breeding durations. RESULTS: A total of 331 ARG subtypes and 71 mobile genetic element (MGE) subtypes were annotated across all samples. ARG Shannon diversity differed overall across groups (Kruskal-Wallis, p = 0.03); Bonferroni-adjusted Dunn's test showed no significant pairwise differences. PCoA (Bray-Curtis) demonstrated distinct separation of the ST group (p = 0.002), and shared core ARG subtypes gradually increased with extended breeding years. A strong positive correlation between ARG and MGE abundances was identified (r = 0.85, p = 0.0001). In total, 63 contigs carrying co-localized ARG-MGE complexes were recovered. The ST group contained the highest proportion of such contigs. The ST group displayed tight physical ARG-MGE linkage within 1-3 kb genomic intervals. CONCLUSIONS: Our results reveal that breeding duration is associated with the gut ARG characteristics of captive forest musk deer. Short-term captivity has higher ARG-MGE co-localization, suggesting a higher possibility of mobilization.

One Health

Horizontal plasmid transfer promotes antibiotic resistance in selected bacteria in Chinese frog farms.

The emergence and dissemination of antibiotic resistance genes (ARGs) in the ecosystem are global public health concerns. One Health emphasizes the interconnectivity between different habitats and seeks to optimize animal, human, and environmental health. However, information on the dissemination of antibiotic resistance genes (ARGs) within complex microbiomes in natural habitats is scarce. We investigated the prevalence of antibiotic resistant bacteria (ARB) and the spread of ARGs in intensive bullfrog (Rana catesbeiana) farms in the Shantou area of China. Antibiotic susceptibilities of 361 strains, combined with microbiome analyses, revealed Escherichia coli, Edwardsiella tarda, Citrobacter and Klebsiella sp. as prevalent multidrug resistant bacteria on these farms. Whole genome sequencing of 95 ARB identified 250 large plasmids that harbored a wide range of ARGs. Plasmid sequences and sediment metagenomes revealed an abundance of tetA, sul1, and aph(3″)-Ib ARGs. Notably, antibiotic resistance (against 15 antibiotics) highly correlated with plasmid-borne rather than chromosome-borne ARGs. Based on sequence similarities, most plasmids (62%) fell into 32 distinct groups, indicating a potential for horizontal plasmid transfer (HPT) within the frog farm microbiome. HPT was confirmed in inter- and intra-species conjugation experiments. Furthermore, identical mobile ARGs, flanked by mobile genetic elements (MGEs), were found in different locations on the same plasmid, or on different plasmids residing in the same or different hosts. Our results suggest a synergy between MGEs and HPT to facilitate ARGs dissemination in frog farms. Mining public databases retrieved similar plasmids from different bacterial species found in other environmental niches globally. Our findings underscore the importance of HPT in mediating the spread of ARGs in frog farms and other microbiomes of the ecosystem.

Animals

Amplicon and metagenomic sequencing reveal thifluzamide drive rhizosphere microbial structural shifts and functional adaption.

Thifluzamide (TF) is a widely used phenyl urea fungicide in rice production; however, its impacts on the structural composition and functional dynamics of the rhizosphere microbiome remain poorly understood. Here, we systematically investigated the effects of TF on the structure, interactions, and functional potential of the rice (Oryza sativa L.) rhizosphere microbiome using integrated amplicon sequencing and metagenomic approaches. TF application significantly altered both bacterial and fungal community composition, bacterial diversity was markedly reduced, whereas fungal diversity increased. With bacterial diversity markedly reduced while fungal diversity increased. Beta-diversity analyses revealed strong treatment-driven community separation, indicating pronounced TF-induced microbial restructuring. Co-occurrence network analysis demonstrated reduced complexity and connectivity in bacterial networks but increased negative co-occurrence patterns within fungal communities, suggesting contrasting stability responses between microbial kingdoms. Metagenomic profiling further revealed substantial functional shifts, including the differential enrichment of KEGG and COG pathways associated with xenobiotic metabolism. Notably, while total ARG abundance remained stable, TF exposure altered the resistome profile by selectively enriching specific classes of antibiotic resistance genes (ARGs), biocide resistance genes (BRGs), and mobile genetic elements (MGEs). Strong positive correlations between MGEs and ARGs highlighted an elevated potential for horizontal gene transfer. Metagenome-assembled genome (MAG) analysis identified specific TF-enriched bacterial taxa, including Methylophilus, Sulfurospirillum, and Azospirillum, which harbored genes involved in pesticide degradation and xenobiotic transformation. Collectively, these findings demonstrate that TF profoundly reshapes the rice rhizosphere microbiome by altering microbial diversity, interaction networks, resistance gene profiles, and functional capacities. This study provides genomic insights into fungicide-microbiome interactions, underscoring the potential ecological implications associated with TF application, while identifying candidate microbial taxa that may contribute to pesticide degradation and rhizosphere microecology resilience.

Rhizosphere

Evolution, Mechanisms, and Therapeutic Implications of Mobile Tetracycline Destructases.

Tetracycline destructases (TDases) pose an emerging global threat by enzymatically inactivating all generations of tetracycline (Tet) antibiotics, including last-resort agents such as tigecycline. Despite their recent identification, TDases have rapidly disseminated worldwide, largely driven by mobile genetic elements and environmental reservoirs. This review synthesizes current knowledge on TDase genomics, structural and catalytic mechanisms, ecological niches, and clinical impacts. We detail the mechanistic distinctions between type 1 and type 2 TDases, emphasizing their divergent structural configurations and substrate specificity profiles. Additionally, we examine strategies for therapeutic intervention, highlighting progress in structure-guided inhibitor development. Key gaps remain in understanding ancestral reservoirs, evolutionary trajectories, and effective surveillance strategies. Addressing these areas through integrative evolutionary, biochemical, and ecological studies is critical for mitigating the clinical spread and therapeutic impact of TDases globally.

Humans

Synergistic removal of total petroleum hydrocarbons and antibiotic resistance genes in Yellow River Delta wetlands contaminated soil composting regulated by biogas slurry addition.

The interactive effects between the emerging contaminant antibiotic resistance genes (ARGs) and the traditional pollutant total petroleum hydrocarbons (TPHs) in contaminated soils remain unclear. The synergistic removal of TPHs and ARGs from composted contaminated soil, along with the microbial mechanisms driven by the addition of biogas slurry, have not yet been investigated. This study explored the impact of biogas slurry on the synergistic degradation mechanisms and bacterial community dynamics of ARGs and TPHs in compost derived from contaminated soil. The addition of biogas slurry resulted in a reduction of targeted ARGs and mobile genetic elements (MGEs) by 9.96%-95.70% and 13.32%-97.66%, respectively. Biogas slurry changed the succession of bacterial communities during composting, thereby reducing the transmission risk of ARGs. Pseudomonas, Cellvibrio, and Devosia were identified as core microorganisms in the synergistic degradation of ARGs and TPHs. According to the partial least squares path model, temperature and NO3- indirectly influenced the removal of ARGs and TPHs by directly regulating the abundance and composition of host microbes and MGEs. In summary, the results of this study contribute to the high-value utilization of biogas slurry and provide methodological support for the low-cost remediation of contaminated soils.

Composting

Why do bacteria accumulate antiphage defence systems?

While it is well established that bacterial genomes encode multiple and diverse antiphage systems, the reasons for their co-occurrence and their heterogeneous distribution remain debated. This review examines why bacteria accumulate antiphage systems and how this influences phage-bacteria interactions, particularly in the context of phage therapy. Two main hypotheses may explain this phenomenon: (i) the pan-immunity hypothesis, which suggests that defence system accumulation provides protection against phage predation at the community level, and (ii) mobile genetic element (MGE) competition, where defence systems primarily protect intra-bacterial MGEs against other ones rather than the bacterial host itself. The ecological context also influences the distribution of antiphage systems, with defencee accumulation shaping phage-bacteria interactions in diverse communities but playing a lesser role at the species level, potentially explaining why multiple defences do not strongly limit phage host range in therapeutic settings. Finally, we address the challenges in understanding the drivers shaping the distribution of defence systems across bacterial genomes (expressions, costs, etc.) and their implications for elucidating the ecological role of defence systems and optimizing phage therapy strategies.This article is part of the discussion meeting issue 'The ecology and evolution of bacterial immune systems'.

Bacteria

Mobilome-driven antimicrobial resistance in a one health context: evidence and lessons from Africa.

Antimicrobial resistance (AMR) is one of the most urgent global health threats and is increasingly recognized as a One Health challenge driven by interactions among human, animal, and environmental reservoirs. Central to the emergence and dissemination of AMR across these interfaces are mobile genetic elements (MGEs), which form an interconnected mobilome capable of transferring resistance genes across bacterial taxa and ecological niches. These elements facilitate the accumulation and spread of multidrug resistance determinants and are shaped by co-selective pressures operating at the animal-environment-human interface. Despite their critical role, genomic surveillance of MGEs remains limited, particularly in high-burden regions such as Africa. This narrative review synthesizes evidence from published genomic surveillance studies, primarily whole-genome sequencing-based analyses, to examine the distribution and dynamics of AMR genes and MGEs across One Health interfaces. We highlight animal-environmental systems as major hotspots for mobilome-driven resistance dissemination and also evaluate key advances, methodological approaches, and persistent surveillance challenges and gaps specific across Africa. By integrating findings from diverse genomic studies, and highlighting key lessons and implementation gaps from One Health studies across Africa, this review underscores the need for coordinated One Health surveillance strategies to better capture mobilome dynamics and inform sustainable AMR control efforts.

Africa