Environmental Pathogens Research Articles

Selective enrichment of high-risk antibiotic resistance genes and priority pathogens in freshwater plastisphere: Unique role of biodegradable microplastics

Microplastics (MPs) has been concerned as emerging vectors for spreading antibiotic resistance and pathogenicity in aquatic environments, but the role of biodegradable MPs remains largely unknown. Herein, field in-situ incubation method combined with metagenomic sequencing were employed to reveal the dispersal characteristics of microbial community, antibiotic resistance genes (ARGs), mobile genetic elements (MGEs), and virulence factors (VFs) enriched by MPs biofilms. Results showed that planktonic microbes were more prone to enrich on biodegradable MPs (i.e., polyhydroxyalkanoate and polylactic acid) than non-biodegradable MPs (i.e., polystyrene, polypropylene and polyethylene). Distinctive microbial communities were assembled on biodegradable MPs, and the abundances of ARGs, MGEs, and VFs on biofilms of biodegradable MPs were much higher than that of non-biodegradable MPs. Notably, network analysis showed that the biodegradable MPs selectively enriched pathogens carrying ARGs, VFs and MGEs concurrently, suggesting a strong potential risks of co-spreading antibiotic resistance and pathogenicity through horizontal gene transfer. According to WHO priority list of Antibiotic Resistant Pathogens (ARPs) and ARGs health risk assessment framework, the highest abundances of Priority 1 ARPs and Rank I risk ARGs were found on polylactic acid and polyhydroxyalkanoate, respectively. These findings elucidate the unique and critical role of biodegradable MPs for selective enrichment of high-risk ARGs and priority pathogens in freshwater environments.

Evaluation of the Antimicrobial Activity of Triple Enzyme-Embedded Organic-Inorganic Hybrid Nanoflowers (hNFs) in Comparison with Powerful Antimicrobial Agent Chitosan.

Organic-inorganic hybrid nanoflowers (hNFs) have high stability, reusability, low production cost, and overcome substrate/product inhibition. Antimicrobial activity of various hNFs has been reported to overcome environmental microbial contaminations and infections, which are considered major public health problems. α-amylase, protease, and lipase are the most common industrial enzymes exerting antimicrobial activity; therefore, we synthesized triple enzyme (α-amylase, protease, and lipase)-embedded hNFs by using pancreatin to evaluate their antimicrobial activity in comparison with one of the most potent antimicrobial polymer chitosan. The broad spectrum of the antimicrobial properties of chitosan is used in industrial products, including cosmetics, food, agriculture, pharmaceuticals, and textiles. SEM analysis, thermogravimetric analysis (TGA), and the degree of deacetylation (%DD) were performed for chitosan characterization, where SEM, FTIR, EDX, and XRD analyses were performed for the characterization of hNFs. The catalytic activity of pancreatin and hNFs was evaluated by measuring lipase, α-amylase, and protease enzyme activities at 37°C. Antibacterial activities of hNFs, pancreatin, and chitosan were tested on gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria, compared to the pancreatin and chitosan via agar and broth dilution methods. hNFs showed enhanced catalytic activity for protease, lipase, and α-amylase compared to pancreatin at different pH values (pH 8, 9). hNFs showed catalytic activity after being washed and reused up to six times, indicating their reusability and recoverability. hNFs showed significant antimicrobial activity, such as chitosan, Staphylococcus aureus, and Escherichia coli, compared to pancreatin. Our novel hNFs can be used to develop antimicrobial technologies to fight against environmental microbial contaminations and antibiotic resistance-driven environmental pathogens.

Serotonin deficiency from constitutive SKN-1 activation drives pathogen apathy

When an organism encounters a pathogen, the host innate immune system activates to defend against pathogen colonization and toxic xenobiotics produced. C. elegans employ multiple defense systems to ensure survival when exposed to Pseudomonas aeruginosa including activation of the cytoprotective transcription factor SKN-1/NRF2. Although wildtype C. elegans quickly learn to avoid pathogens, here we describe a peculiar apathy-like behavior towards PA14 in animals with constitutive activation of SKN-1, whereby animals choose not to leave and continue to feed on the pathogen even when a non-pathogenic and healthspan-promoting food option is available. Although lacking the urgency to escape the infectious environment, animals with constitutive SKN-1 activity are not oblivious to the presence of the pathogen and display the typical pathogen-induced intestinal distension and eventual demise. SKN-1 activation, specifically in neurons and intestinal tissues, orchestrates a unique transcriptional program which leads to defects in serotonin signaling that is required from both neurons and non-neuronal tissues. Serotonin depletion from SKN-1 activation limits pathogen defenses capacity, drives the pathogen-associated apathy behaviors and induces a synthetic sensitivity to selective serotonin reuptake inhibitors. Taken together, our work reveals interesting insights into how animals perceive environmental pathogens and subsequently alter behavior and cellular programs to promote survival.

PSI-17 Anti-endotoxin immunoglobulin (Ig) Y time course of oral passive transfer and impacts on growth performance in foals

Abstract Foal diarrhea is the leading cause of morbidity in neonatal foals and is often caused by various environmental pathogens. The adaptive immune system of foals depends on postpartum Ig absorption from maternal colostrum. To date, there lacks an easy way to supplement the immune system before intestinal closure. Thus, an anti-endotoxin IgY supplement derived from hyperimmunized hens may provide pathogen-specific protection if successful in passive transfer. Therefore, the objective was to determine the effects of an oral anti-endotoxin IgY on growth, stress, and passive transfer in neonatal foals with the hypothesis that IgY would successfully cross the gut barrier, positively impact growth, and ameliorate stress. To test this, Quarter Horse foals (n = 11) were randomly assigned based on foaling date to one of two treatment groups for a 28-d trial. Upon signs of impending parturition, mares were moved to box stalls (3.7 × 7.3 m) and parturition was attended. At birth, foals were assigned to either the control (CON; n = 5) or treatment group (TRT; n = 6). Foals assigned to TRT were supplemented with 40 g egg-derived anti-endotoxin IgY oral supplement (Camas, Inc.) dissolved in 50 mL ddH20 at 20 min after nursing and again at 12 h postpartum. The CON foals received isovolumetric ddH2O. Beginning at h 24, and daily thereafter, TRT foals received 1 g egg-derived anti-endotoxin IgY diluted in 5 mL ddH2O. Blood samples were collected from foals prior to nursing at h 0 and following the first oral treatment at h 2, 6,12, 24 and d 3, 7, 14, 21, 28. Harvested serum was analyzed for IgG, IgA, IgY, and cortisol by commercial ELISA. Data were analyzed using PROC MIXED in SAS v9.4 with repeated measures of time. Vital signs were similar for all foals regardless of treatment (P > 0.24) and all growth parameters increased over time (P < 0.01). There tended to be a treatment × time interaction for wither height (P = 0.10) where TRT wither height was greater at d 28 (P = 0.07). There was a treatment × time interaction (P < 0.01) for serum IgY concentrations where CON foals had undetectable concentrations for the duration of the study and TRT foals peaked on d 7 with detectable l concentrations remaining on d 28. Cortisol, however, was not influenced by treatment (P > 0.29), and IgG and IgA concentrations were only influenced by time (P < 0.01). In conclusion, despite having no effect on vital signs and stress, IgY is passively absorbed following oral administration to neonatal foals without negatively impacting the passive transfer of maternal IgG or IgA, lending to future work on pathogen-specific protection against foal diarrhea.

Analysis of genetic signatures of virulence and resistance in foodborne Staphylococcus aureus isolates from Algeria

Staphylococcus aureus, a frequent commensal of the human microbiota, also frequently associated with various infections. This study aimed to genetically characterize foodborne methicillin resistant S. aureus (MRSA) in Oran, Algeria. From a total of 474 food matrices, 30 MRSA strains were isolated and characterized using whole genome sequencing (WGS) and bioinformatics. The genomes were assessed for antimicrobial resistance and virulence genes, sequence and spa types and single nucleotide polymorphism (SNP) to establish their relationship. The prevalence of S. aureus was 34.38% with MRSA accounting for 18.40%. MRSA strains showed high resistance to penicillinG, ampicillin and tetracycline. However, inconsistencies were noted between phenotypic and genotypic resistance for methicillin, aminoglycosides, and phenicolates, with mecA gene identified in three isolates. The isolates revealed eight different sequence types (predominantly ST97 and ST45) and eleven spa types (mainly t230 and t8503), correlating with SNP clusters except for isolates belonging to ST7200.86.66% of isolates harboured at least one enterotoxin gene underscores their potential public health threat. This investigation highlights the genetic heterogeneity among S. aureus regarding virulence and antimicrobial resistance, shedding light into food safety in Algeria and the ease of using WGS approach to rapidly characterize bacterial pathogens in community environments.

The occurrence of Aerococcus urinaeequi and non-aureus staphylococci in raw milk negatively correlates with Escherichia coli clinical mastitis.

Escherichia coli is a common environmental pathogen associated with clinical mastitis (CM) in dairy cattle. There is an interest in optimizing the udder microbiome to increase the resistance of dairy cattle to E. coli CM; however, the details of which members of the healthy udder microbiome may play a role in antagonizing E. coli are unknown. In this study, we characterized the bacterial community composition in raw milk collected from quarters of lactating Holstein dairy cows that developed E. coli CM during lactation, including milk from both healthy and diseased quarters (n = 1,172). The milk microbiome from infected quarters was compared before, during, and after CM. A combination of 16S rRNA gene amplicon and metagenomic sequencing was used generate data sets with a high level of both depth and breadth. The microbial diversity present in raw milk significantly decreased in quarters experiencing E. coli CM, indicating that E. coli displaces other members of the microbiome. However, the diversity recovered very rapidly after infection. Two genera, Staphylococcus and Aerococcus, and the family Oscillospiraceae were significantly more abundant in healthy quarters with low inflammation. Species of these genera, Staphylococcus auricularis, Staphylococcus haemolyticus, and Aerocussus urinaeequi, were identified by metagenomics. Thus, these species are of interest for optimizing the microbiome to discourage E. coli colonization without triggering inflammation.IMPORTANCEIn this study, we show that E. coli outcompetes and displaces several members of the udder microbiome during CM, but that microbial diversity recovers post-infection. In milk from quarters which remained healthy, the community composition was often highly dominated by S. auricularis, S. haemolyticus, A. urinaeequi, and S. marcescens without increases in somatic cell count (SCC). Community dominance by these organisms, without inflammation, could indicate that these species might have potential as prophylactic probiotics which could contribute to colonization resistance and prevent future instances of E. coli CM.

CTAB-crafted ZnO nanostructures for environmental remediation and pathogen control

This study addresses the critical need for efficient and sustainable methods to tackle organic pollutants and microbial contamination in water. The present work aim was to investigate the potential of multi-structured zinc oxide nanoparticles (ZnO NPs) for the combined photocatalytic degradation of organic pollutants and antimicrobial activity. A unique fusion of precipitation-cum-hydrothermal approaches was precisely employed to synthesize the ZnO NPs, resulting in remarkable outcomes. The synthesized CTAB/ZnO NPs demonstrated exceptional properties: they were multi-structured and crystalline with a size of 40 nm and possessed a narrow band gap energy of 2.82 eV, enhancing light absorption for photocatalysis. These nanoparticles achieved an impressive degradation efficiency of 91.75% for Reactive Blue-81 dye within 105 min under UV irradiation. Furthermore, their photocatalytic performance metrics were outstanding, including a quantum yield of 1.73 × 10–4 Φ, a kinetic reaction rate of 3.89 × 102 µmol g–1 h–1, a space–time yield of 8.64 × 10–6 molecules photon–1 mg–1, and a figure-of-merit of 1.03 × 10–9 mol L J–1 g–1 h–1. Notably, the energy consumption was low at 1.73 × 10–4 J mol–1, compared to other systems. Additionally, the ZnO NPs exhibited effective antimicrobial activity against S. aureus and P. aeruginosa. This research underscores the potential of tailored ZnO NPs as a versatile solution for addressing both organic pollution and microbial contamination in water treatment processes. The low energy consumption further enhances its attractiveness as a sustainable solution.

The influence of social and spatial processes on the epidemiology of environmentally transmitted pathogens in wildlife: implications for management.

Social and spatial structures of host populations play important roles in pathogen transmission. For environmentally transmitted pathogens, the host space use interacts with both the host social structure and the pathogen's environmental persistence (which determines the time-lag across which two hosts can transmit). Together, these factors shape the epidemiological dynamics of environmentally transmitted pathogens. While the importance of both social and spatial structures and environmental pathogen persistence has long been recognized in epidemiology, they are often considered separately. A better understanding of how these factors interact to determine disease dynamics is required for developing robust surveillance and management strategies. Here, we use a simple agent-based model where we vary host mobility (spatial), host gregariousness (social) and pathogen decay (environmental persistence), each from low to high levels to uncover how they affect epidemiological dynamics. By comparing epidemic peak, time to epidemic peak and final epidemic size, we show that longer infectious periods, higher group mobility, larger group size and longer pathogen persistence lead to larger, faster growing outbreaks, and explore how these processes interact to determine epidemiological outcomes such as the epidemic peak and the final epidemic size. We identify general principles that can be used for planning surveillance and control for wildlife host-pathogen systems with environmental transmission across a range of spatial behaviour, social structure and pathogen decay rates. This article is part of the theme issue 'The spatial-social interface: a theoretical and empirical integration'.

A cholera model coupling within-host and between-host with age-dependent and asymptomatic infections

In this paper, a coupling cholera epidemic model is proposed, in which the pathogens could both spread within-host and between-host, meanwhile, there exist age-dependent infection between the asymptomatic and symptomatic infected people. For the fast-time subsystem, the infection-free and endemic equilibria are both globally asymptotically stable. For the slow-time subsystem, the basic reproduction number R0 is determined, by which we observe that the disease-free equilibrium is globally asymptotically stable (the absence of pathogens in environment) if R0<1, while the endemic equilibrium is globally asymptotically stable (the presence of pathogens in environment) when R0>1. The theoretical results are illustrated by numerical simulations, by which we find that age-dependent and asymptomatic infections may further promote cholera spread. Besides, the linking of pathogen transmission at the individual level with infection at the population level could result in forward or backward bifurcation.

The contribution of swine wastewater on environmental pathogens and antibiotic resistance genes: Antibiotic residues and beyond

Swine wastewater application can introduce antibiotics, antibiotic resistance genes (ARGs) into environments. Herein, the full-scale transmission of antibiotics, ARGs and their potential carriers from an intensive swine feedlot to its surroundings were explored. Results showed that lincomycin and doxycycline hydrochloride were dominant antibiotics in this ecosystem. Lincomycin concentration were strongly associated with soil bacterial communities. According to the risk quotient (RQ), lincomycin was identified as posing higher ecological risk in aquatic environments. ARGs and mobile genetic elements (MGEs) abundance in wastewater were reduced after anaerobic treatment. Notably, ARGs composition of environmental samples were clustered into two groups based on if they were directly affected by the wastewater. However, there were no remarkable difference of ARGs abundance among environmental samples. The total abundance of ARGs was positively related to that of MGEs. Pathogens Escherichia coli and Enterococcus revealed strong connection with qnrS, tet and sul. Overall, this study highlights the importance of responsible antibiotics use in livestock production and appropriate treatment technology before agricultural application and discharge.

An overview of Buruli ulcer in Australia.

Buruli ulcer (BU) is caused by Mycobacterium ulcerans, an environmental pathogen that causes severe skin and soft-tissue necrosis. In Australia, cases of BU are acquired in endemic regions, which include Victoria and Far North Queensland, but those who have visited these regions can present to health practitioners anywhere. This article provides Australian general practitioners with an overview of BU, including its epidemiology, transmission, clinical features, diagnosis and management. BU can manifest as an ulcer or as a non-ulcerated skin lesion, such as a plaque, nodule or oedema. Diagnosis can be achieved with a dedicated Mycobacterium ulcerans polymerase chain reaction (PCR) test performed on a wound swab. Swabs on non-ulcerated disease have a high false negative rate, and a PCR test should be performed on a tissue biopsy to confirm disease. Most cases are managed with prolonged antibiotic therapy - commonly a combination of oral rifampicin and clarithromycin or fluroquinolone (moxifloxacin or ciprofloxacin) - and wound dressings.

Distribution of Bovine Mastitis Pathogens in Quarter Milk Samples from Bavaria, Southern Germany, between 2014 and 2023-A Retrospective Study.

The objective of this study was to investigate the distribution of mastitis pathogens in quarter milk samples (QMSs) submitted to the laboratory of the Bavarian Animal Health Service (TGD) between 2014 and 2023 in general, in relation to the clinical status of the quarters, and to analyze seasonal differences in the detection risk. Each QMS sent to the TGD during this period was analyzed and tested using the California Mastitis Test (CMT). Depending on the result, QMSs were classified as CMT-negative, subclinical, or clinical if the milk character showed abnormalities. Mastitis pathogens were detected in 19% of the QMSs. Non-aureus staphylococci (NAS) were the most common species isolated from the culture positive samples (30%), followed by Staphylococcus (S.) aureus (19%), Streptococcus (Sc.) uberis (19%), and Sc. dysgalactiae (9%). In culture-positive QMSs from CMT-negative and subclinically affected quarters, the most frequently isolated pathogens were NAS (44% and 27%, respectively), followed by S. aureus (25% and 17%, respectively) and Sc. uberis (8% and 22%, respectively). In QMSs from clinically affected quarters, the most frequently isolated pathogens were Sc. uberis (32%), S. aureus (13%), Sc. dysgalactiae (11%), and Escherichia (E.) coli (11%). The distribution of NAS and Sc. uberis increased throughout the study period, while that of S. aureus decreased. From June to October, QMSs from subclinically affected quarters increased and environmental pathogens, such as Sc. uberis, were detected more frequently. In conclusion, this study highlights the dynamic nature of the distribution of mastitis pathogens, influenced by mastitis status and seasonal factors. Environmental pathogens still play an important role, especially in clinical mastitis and seasonal dependency, with the number of positive samples continuing to increase. It is therefore essential to continue mastitis control measures and to regularly monitor the spread of mastitis pathogens in order to track trends and adapt targeted prevention measures.

Expansion of human γδ T cells in periphery: Lessons learned from development, infections, and compromised thymic function.

γδ T cells predominantly develop in the fetal period. Post birth they respond swiftly to environmental insults, pathogens and tumors, especially when other immune effector cells are less ready to function. Most of our understanding of γδ T-cell development, peripheral adaptation, and function derives from murine studies. The recent advancement of immunological methods allows now to decipher human γδ T-cell biology in patient cohorts and tissue samples, and to manipulate them using in vitro systems. In this review, we summarize γδ T-cell development in the human thymus, their functional adaptation to the microbial environment from birth until old age, and their capacity to expand and fill up the peripheral niche under conditions of perturbations of conventional T-cell development.

A mechanistic modeling and estimation framework for environmental pathogen surveillance

Environmental pathogen surveillance is a promising disease surveillance modality that has been widely adopted for SARS-CoV-2 monitoring. The highly variable nature of environmental pathogen data is a challenge for integrating these data into public health response. One source of this variability is heterogeneous infection both within an individual over the course of infection as well as between individuals in their pathogen shedding over time. We present a mechanistic modeling and estimation framework for connecting environmental pathogen data to the number of infected individuals. Infected individuals are modeled as shedding pathogen into the environment via a Poisson process whose rate parameter λt varies over the course of their infection. These shedding curves λt are themselves random, allowing for variation between individuals. We show that this results in a Poisson process for environmental pathogen levels with rate parameter a function of the number of infected individuals, total shedding over the course of infection, and pathogen removal from the environment. Theoretical results include determination of identifiable parameters for the model from environmental pathogen data and simple, explicit formulas for the likelihood for particular choices of individual shedding curves. We give a two step Bayesian inference framework, where the first step corresponds to calibration from data where the number of infected individuals is known, followed by an estimation step from environmental surveillance data when the number of infected individuals is unknown. We apply this modeling and estimation framework to synthetic data, as well as to an empirical case study of SARS-CoV-2 in environmental dust collected from isolation rooms housing university students. Both the synthetic data and empirical case study indicate high inter-individual variation in shedding, leading to wide credible intervals for the number of infected individuals. We examine how uncertainty in estimates of the number of infected individuals from environmental pathogen levels scales with the true number of infected individuals and model misspecification. While credible intervals for the number of infected individuals are wide, our results suggest that distinguishing between no infection and small-to-moderate levels of infection (≈10 infected individuals) may be possible, and that it is broadly possible to differentiate between moderate (≈40) and high (≈200) numbers of infected individuals.

In vitro analysis of antiviral immune response against avian influenza virus in chicken tracheal epithelial cells.

Avian influenza virus (AIV) infections first affect the respiratory tract of chickens. The epithelial cells activate the host immune system, which leads to the induction of immune-related genes and the production of antiviral molecules against external environmental pathogens. In this study, we used chicken tracheal epithelial cells (TECs) in vitro model to investigate the immune response of the chicken respiratory tract against avian respiratory virus infections. Eighteen-day-old embryonic chicken eggs were used to culture the primary chicken TECs. Reverse transcription-polymerase chain reaction (RT-PCR) and immunocytochemistry (ICC) analysis of epithelial cell-specific gene makers were performed to confirm the characteristics, morphology, and growth pattern of primary cultured chicken TECs. Moreover, to investigate the cellular immune response to AIV infection or polyinosinic-polycytidylic acid (poly (I:C)) treatment, the TECs were infected with the H5N1 virus or poly (I:C). Then, immune responses were validated by RT-qPCR and western blotting. The TECs exhibited polygonal morphology and formed colony-type cell clusters. The RT-qPCR results showed that H5N1 infection induced a significant expression of antiviral genes in TECs. We found that TECs treated with poly (I:C) and exposed to AIV infection-mediated activation of signaling pathways, leading to the production of antiviral molecules (e.g., pro-inflammatory cytokines and chemokines), were damaged due to the loss of junction proteins. We observed the activation of the nuclear factor kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) pathways, which are involved in inflammatory response by modulating the release of pro-inflammatory cytokines and chemokines in TECs treated with poly (I:C) and pathway inhibitors. Furthermore, our findings indicated that poly (I:C) treatment compromises the epithelial cell barrier by affecting junction proteins in the cell membrane. Our study highlights the utility of in vitro TEC models for unraveling the mechanisms of viral infection and understanding host immune responses in the chicken respiratory tract.

Breathing Clean Air: Navigating Indoor Air Purification Techniques and Finding the Ideal Solution.

The prevalence of airborne pathogens in indoor environments presents significant health risks due to prolonged human occupancy. This review addresses diverse air purification systems to combat airborne pathogens and the factors influencing their efficacy. Indoor aerosols, including bioaerosols, harbor biological contaminants from respiratory emissions, highlighting the need for efficient air disinfection strategies. The COVID-19 pandemic has emphasized the dangers of airborne transmission, highlighting the importance of comprehending how pathogens spread indoors. Various pathogens, from viruses like SARS-CoV-2 to bacteria like Mycobacterium (My) tuberculosis, exploit unique respiratory microenvironments for transmission, necessitating targeted air purification solutions. Air disinfection methods encompass strategies to reduce aerosol concentration and inactivate viable bioaerosols. Techniques like ultraviolet germicidal irradiation (UVGI), photocatalytic oxidation (PCO), filters, and unipolar ion emission are explored for their specific roles in mitigating airborne pathogens. This review examines air purification systems, detailing their operational principles, advantages, and limitations. Moreover, it elucidates key factors influencing system performance. In conclusion, this review aims to provide practical knowledge to professionals involved in indoor air quality management, enabling informed decisions for deploying efficient air purification strategies to safeguard public health in indoor environments.

The fate of antibiotics and antibiotic resistance genes in Large-Scale chicken farm Environments: Preliminary view of the performance of National veterinary Antimicrobial use reduction Action in Guangdong, China

In 2018, China implemented the Veterinary Antimicrobial Use Reduction Action to curb the rapid development of antibiotic resistance (AR). However, the AR-related pollutions in animal farms after the reduction policy has been poorly investigated. Here, we performed a comprehensive investigation combining UPLC-MS/MS, metagenomic, and bacterial genomic analyses in eight representative large-scale chicken farms in Guangdong, China. Our results showed that antibiotics and ARGs contaminations were more severe in broiler farms than in layer farms. Notably, diverse tet(X) variants were prevalent in the chicken farms. These tet(X)s was carried by diverse E. coli lineages and obviously correlated with ISCR2 and IS1B transposases. The resistomes in chicken farms was significantly correlated with microbial community, and multiple factor analyses indicated that the joint effect of antibiotics-microbial community-MGEs was the most dominant driver of ARGs. Host tracking identified a variety of ARG bacterial hosts and the co-occurrence of ARGs-MRGs-MGEs. Source tracking indicated that the inherent component represented the main feature of resistomes in different hosts, while ARG transfer between the chicken gut and farm environments were frequent. A multiperspective evaluation of AR risk revealed that the early effect of antibiotic reduction was exhibited by the mitigation of maximum level of risky ARGs, prevalence of environmental AR pathogens, and HGT potential of ARGs mediated by phage structures. Overall, our findings provide insights into the antibiotic and ARG profiles in large-scale chicken farms with different rearing strategies and demonstrate a preliminary view of the performance of antibiotic reduction actions in China.

Characterization of water microbiota and their relationship with resident oysters during an oyster mortality event.

Microorganisms are vital for the health of marine invertebrates, and their assembly is driven by both deterministic and stochastic factors that regulate residents (innate to the host) and transients (from ambient water). However, the role of water microbiota and the significance of deterministic and stochastic processes in aquatic hosts facing mortality threats are largely unknown. This study examines the shifts in water microbiota during an oyster mortality event using amplicon sequencing and compared with those of resident oysters to disentangle the balance of the deterministic and stochastic factors involved. Water temperature and dissolved oxygen significantly shape the microbial community with a distinct monthly pattern, and Cyanobacteria blooms might exacerbate oyster mortality. The comparative analysis of microbial communities in oysters and water revealed that ≤ 21% of the genera were shared between oysters and water, implying that water microbiota cannot easily transfer into oysters. Furthermore, these shared genera had different functions, with oysters more involved in promoting host digestion and nutrient acquisition and water bacteria enriched more in functions promoting their own growth and survival. These findings illustrate that oysters may possess specific selection or barrier mechanisms that permit a small percentage of transients, controlled by stochastic factors and having a minimal effect on oyster mortality, to enter, whereas the majority of oyster microbiota are residents governed by deterministic factors. Consequently, oysters exhibit some plasticity in their symbiotic microbiota, enabling them to maintain microbial homeostasis and adapt to complex microbial surroundings. This may be a shared mechanism among marine invertebrates for survival in complex marine environments.IMPORTANCEPacific oysters are widely cultured and play vital ecological roles. However, the summer mortality hinders sustainable oyster farming. Untangling causative mechanisms of oyster mortality is a complex task due to the intricate "interactome" involving environmental factors, hosts, and pathogens. Interactions between hosts and microorganisms offer an ideal avenue for investigating the truth. We systematically investigated the microbial community in water and resident oysters during a summer mortality event and proposed that the assembly of oyster microbiota is primarily governed by deterministic processes independent of mortality. Pathogens mainly originate from resident members of the oyster microbiota, with a limited influence from the microbial community in the water. Additionally, environmental degraders, such as Cyanobacteria blooms, cannot be overlooked as a contributing factor of oyster mortality. This study evaluated the weight of deterministic and stochastic factors in microbial assembly during an oyster mortality event and greatly broadened our understanding of the "interactome" through the interaction between oysters and water in microbiota.

Comprehensive analysis of antibiotic and heavy metal resistance, and virulence factors in Aeromonas veronii CTe-01: Implications for global antimicrobial resistance

ObjectivesThis study aimed to characterize Aeromonas veronii CTe-01 focusing on its resistance to heavy metal and antibiotics. MethodsA. veronii CTe-01 was characterized using standard microbiological and molecular techniques. Antibiotic susceptibility and heavy metal resistance were tested per standard protocols. Genomic analysis, including plasmid characterization, was conducted in silico. ResultsA. veronii CTe-01 showed resistance to various heavy metals and antibiotics. Multiple resistance genes were identified, including those for beta-lactamases, heavy metal resistance, and type III secretion system components. The bacterium carries a 9 kb plasmid with repA/repB replication genes, parA/parB partitioning genes, and a type II toxin-antitoxin system for stability. ConclusionsA. veronii CTe-01 is a genetic reservoir for antibiotic resistance, heavy metal resistance genes, and virulence factors. The study offers insights into its dual role as a pathogen and heavy metal remediator in aquatic environments.

Interactions between migration and immunity among oriental armyworm populations infected with the insect pathogenic fungus, Beauveria bassiana.

Migration and immunity are behavioral and physiological traits that protect organisms from environmental stressors or pathogen infection. Shifting from migration to residency has become more common in some wildlife populations owing to environmental changes. However, other biological shifts, such as interactions between migration and immunity among populations within a species are largely unexplored for many agricultural migratory pests. In the field, entomopathogenic fungi infection and transmission, particularly Beauveria bassiana, can cause reduced fitness and population declines across a broad range of insect species. Here, we investigated migration-immunity interactions between migrant and resident populations of the oriental armyworm, Mythimna separata, infected with B. bassiana (the sole fungus used in this work). We found that migratory M. separata exerted stronger pathogen resistance, faster development and lower pupal weight than residents. High-dose infections (5.0 × 105 and 5.0 × 106 conidia mL-1) led to seriously decreased reproductive capacity in migrants and residents. Low-dose infections (1.0 × 104 and 5.0 × 104 conidia mL-1) led to significantly increased host flight capacities. Consecutive flight tests showed that five flight nights inhibited the reproduction of paternal infected M. separata populations. The flights also led to far-reaching transgenerational impairment of larval development and immune defense among offspring populations. By contrast, two flight nights enhanced the reproductive capacities of both M. separata populations and did not exert negative transgenerational effects on offspring populations, which may facilitate migration. This study provides insights into interactions between migration and immunity among M. separata populations. These insights will guide development of future monitoring and management technologies of this pest. © 2024 Society of Chemical Industry.